Loading...
HomeMy WebLinkAboutSWP272000(6) (2) d-c S I�d-t/'vlew (.,,/ ko4,4 c �d-A ►�►-�� �5 G,c!' !�j S' vK_-,,c�,x� t'q/`E'�4�'i2-U'� J��� ����� 4Y1 f z�-e- x x x W W W (y+c W VI ca m o o f� l/4/A5 4 as •,- 04 C14 env (� > �v d � 3 `J ✓ ,�-'"" C/yt,S,. 66,o4-y "�h. (�,y�.�.hc�vc '�,1.ck(C� ���'► (Gi did ���- ���%��> 1 haw `QsX-✓ /'T(o b / tS r4 j e4l- <,,-e-e ;l 4,,& 6-�Jsolp,c lyo Pe 1A 5-e-(3, USC r, �-_ :t Neighborhood Detail Map/Site Map SW 1L FsF-j J 1 1 A 111 1 JL I I P�LXJ r,i P roj e ct L i ts SW�1 \St ``' 167 S 19th a `n SW 21 st S ` ) Q t ` 5 o SW 23rd t S 23rd St -n T J � W SW 27th St C SW 2 th S SW Oth St Ln Q _ 167 a SW 4th St T � a SW 39th St LwJ 8th Note.. TREATMENT WILL NOT BE APPLIED TO WATER OR WETLAND AREAS. 1000 ° 1000 Sccle in Feet P ei WHITWORTH PEST CONTROL INC. 3707 - 98th STREET E. TACOMA, WASHINGTON 98446 Pierce Co. (206) 535.1818 King Co. (206) 248-2222 FACSIMILE TRANSMITTAL SHEET DATE- TO: ATTN REGARDING: NUMLiER OF PAGES: (InciudinR Cover Pag FROM:Whicvorui Pesc Control, Inc . FAX #(206) ' 536-64 2 SIGNED: : Tf you du not receive all the pages indicated please contact us at }{our office number (206) 535-1818. f1� y N �i r;gi P 02 t`•.l! BUG ZAPPERS ARE HARMFUL, NOT HELPFUL Insect electrocutes light traps, also known as "bug zappers" have been extensively t,r�I�. marketed for the past several years with claims they can provide relief from the annoyance of biting mosquitoes and other pests in your back yard. Their effectiveness has been widely doubted and a few studies have shown they are very poor at killing mosquito females (the sex that bites). Now come another study indicating black light traps are not only useless for mosquito, they are potentially harmful to the environment (and not just to the sensitive ears of neighbors trying to sleep next door). Results of a survey of insects caught in an electrocuter black light trap in Neward, DE indicate that nearly all of the insects caught are either harmless or beneficial. Pests, and especially biting pests, do not end up in the traps, According to an article by Timothy Frick and Douglas Tallamy of the University of Delaware published in Entomological News [107(2):77-82] only 31 insects out of 13, 789 trapped and counted (0.22%) in a suburban setting over the course of an entire surnmer were biting flies. "Biting flies" included both female mosquitoes and biting gnats. The largest number of insects (6,670 = 48.4%) were harmless, nonbiting aquatic j insects from nearby rivers and streams. These insects, of course, are a vital part of the aquatic food chau2 and are valuable "fish food". Another important group unfortunately caught in the traps were predators and parasites, that is, biological control orgalusms such as ground beetles and parasitic wasps that help keep insect pest populations naturally low. Predators and parasites accounted for 13.5% of the insects caught (1,868). So how good are bug zappers? This study would indicate they are worst than +� worthless because of the large number of harmless and beneficial insects they kill. Extrapolations calculated by the authors indicate that 4 million bug zappers (four years worth of approximated sales in the U.S.) operating for 40 nights each summer, would destroy in excess of 71 billion nontarget insects each year. The number of rnusquitoes would still be the same as before. It is clear you should save your lid tlioney! k, Prepared by Donald Lewis, Department of Entomology lows State University, Ames, IA 93 1 R;, Extension Bulletin 1066 insect answers PEST MANAGEMENT FOR PREVENTION AND CONTROL OF MOSQUITOES Mosquitoes are important pests. They annoy and bite which by definition utilizes all reasonable methods humans and animals. Also, they may transmit to achieve pest reduction in a way that has the least disease-causing organisms such as malaria and en- negative impact on the environment. cephalitis. While human malaria does not occur in Washington, outbreaks of encephalitis and mosquito On the farm be sure to: transmission thereof do occur from time to time. 1. Remove standing water by drainage or filling with Life Cycle earth. 2. Check irrigation and drainage ditches for leaks of Mosquitoes are always located near water since water seepage and maintain free flow of water. is essential for growth of the immature stages, thus 3. Fill or drain seepage ponds and puddles. the presence of water is crucial in control programs. 4. Grade newly developed land to prevent standing The advice provided here concerns mosquito con- water. trol on your own property—extensive areas of con- 5. Provide drainage away from premises for excess trol are handled by city governments or county mos- irrigation water, or collect in storage sump and quito abatement districts. reuse on land. Control To eliminate breeding places at home: Prevent mosquitoes from breeding by altering their 1. Destroy, flatten,or dispose of tin cans or any other natural habitat. This is the best means of control and artificial water containers. the logical first step in integrated pest management 2. Drain gutters and water from under homes. 3. Change water in bird baths at least twice a week and stock ornamental pools with predacious fish (goldfish work nicely). 4. Fill or drain puddles and ditches near the home; remove weedy vegetation surrounding these areas. ;- 5. Fill tree holes with sand or mortar, or develop 4 drainhole so water cannot accumulate. +p. f 6. Old tires used as planters should have drainholes �^ .� , , • � _ drilled in bottom. E ,•. 7. Pay particular attention to such gardening aids as �� - �• ,.. ;, sheets of discarded, crumpled polyethylene film (often used as plastic mulch). Since these catch M water easily, they provide an excellent almost per- manent breeding site. They shield against evapora- Figure 1. Adult mosquito taking blood meal. . tion, even help moisture condense. Pesticides registered for Mosquito Control Bacillus thuringiensis var. israelensis (SkeetalO, Teknar®, Mosquito Attack®, Bactimos®, etc.) If the problem cannot be solved with cultural methods DDVP (Vapona) such as habitat alteration, then judicious use of Dursban pesticides may be the final alternative. Malathion *Oil, Light Paraffinic Base (e.g., Golden Bear') Pesticides used in mosquito control are designated basically as "Adulticides" and "Larvicides." Adulticides Adulticides are available as "Liquid Concentrates" Baygon primarily designed for use in "Ultra-low Volume" DDVP (Vapona) sprayers, either by aerial applications or by ground- Dursban based equipment; and "Emulsifiable Concentrates" Malathion primarily designed to be suspended in water and used Methoxychlor in relatively coarse sprays. Both forms of concen- *Naled (Dibrom) trates can be diluted with oil and used in thermal fog Pyrethrum (Pyrethrins and Synergist) (piperonyl generators. butoxide) Permethrin Larvicides are available as "Liquid Concentrates," "Emulsifiable Concentrates," as described in the Repellents, especially those containing diethyltolua- preceding paragraph, and as"Granules."Granules are mide, prevent mosquito bites for at least several hours prepared from clay with the pesticide mixed into them up to a full day. Examples include: Deet, Cutters,etc. or as sand granules coated with the pesticide and can be distributed by aerial application or ground-based For more specific instructions as to the formulation, equipment. They are best used in aquatic areas with dosage, and application of these insecticides, con- heavy vegetation canopies and as prehatch applications tact your nearest mosquito control district person. in flood water situations. There are also light paraf- Your county agent may also be able to help you han- finic based oils for use as larvicides as well as some dle specific problems. Your local health department specialty items which release chemicals slowly into the may also be helpful in answering questions on mos- water. quito control in local situations. Due to the many formulations, labels, and label Mosquito Control by Municipal Corporations changes, it is impractical to list specific recom- mendations other than basic pesticides for mosquito Frequently mosquito control by an individual or a control. small group of individuals is impractical because the problem is too extensive. With respect to the following list of pesitcides used in mosquito control, the following two items cannot Under these conditions, a more extensive control pro- be overstressed: gram may be organized by the formation of a vec- 1. Always follow label directions. for control district or a mosquito abatement district, 2. Always be aware of precautions regarding or by having a program instituted through the local fishbearing waters, wildlife, nontarget aquatic life, health department. Whether the county administra- and beneficial insects, such as honey bees. tion institutes such a program or a formal district is formed will depend upon the wishes of the taxpayers Larvicides and voters of the area involved. *Abate Altosid XR Briquets (Methoprene) * Commercial use only. The first step in organizing a formal program of mos- For this type of action, legal counsel should be quito control is a survey to establish the severity of obtained. the problem, the major mosquito producing sources, and the area involved. Assistance from the local Technical consultation and advice on mosquito health department or appropriate office of the respon- prevention and control may be obtained from the ap- sible state health department is available. The infor- propriate state health departments or from Extension mation acquired from this survey should be correlated offices. with a feasibility study. This study should report on the need for a program, methods of organizing a for- mal control program, specific recommendations on methods of control, and economic ramifications ^,Y V YRS resulting from control activities. ! i.`X;� + �{ a c♦L,: t `i.tidy tiu� If the report recommends a control program ad- ministered by county authorities(usually local health department),concerned citizens should then petition ' xA 3. the governing body of the county to institute such a program, with financing to be provided through d� . the appropriate county budget. g , Conversely, if the report recommends a control pro- s gram conducted by a formally organized district,.then appropriate action as prescribed by the applicable state law or laws must be taken.This usually involves Figure 2. Aquatic larval form of mosquito taking preparation of a petition, hearings, and an election. in air at surface of water. By Arthur L. Antonelli, Extension Entomologist, WSU Puyallup. College of Agriculture and Home Economics, Pullman, Washington ♦Warning. Use pesticides with care. Apply them only to plants,animals,or sites listed on the label. When mixing and applying pesticides, follow all label precautions to protect yourself and others around you. It is a violation of the law to disregard label direc- tions. If pesticides are spilled on skin or clothing, remove clothing and wash skin thoroughly. Store pesticides in their original con- tainers and keep them out of the reach of children, pets, and livestock. Issued by Washington State University Cooperative Extension, Larry G. James, Interim Director, and the U.S. Department of Agriculture in furtherance of the Acts of May 8 and June 30, 1914. Cooperative Extension programs and policies are consistent with federal and state laws and regulations on nondiscrimination regarding race,color,national origin,religion,gender,age,disability, and gender preference.Trade names have been used to simplify information. No endorsement is intended. Revised February 1993. Subject Code 670. A EB 1066 This pamphlet is intended to answer some of the most commonly asked questions about mosquito control. The control of mosquitoes is a major concern. Public health pro- fessionals continue to monitor the diseases mosquitoes transmit; encephalitis,malaria,yellow Commonly fever, and dengue viruses. One must also consider the nuisance factor,the discomfort mosquito bites cause while we try to enjoy Asked the outdoors. Fortunately, modern methods ZANUS CORPORATION of mosquito control have advanced to the point of being 1259 El Camino Real, Suite 134 Questions able to maintain comfort and MENLO PARK,CA. 94023 prevent disease. Phone: (800) 347-7783 Fax: (415.)637-9927 About Clarke Environmental Mosquito Mosquito Management, Inc. ce ® 1-800-942-2555 Control or Clarke Mosquito Control Products, Inc. 1-800-323-5727 t P.O. Box 72197 159 North Garden Avenue Roselle, IL 60172 Environmental Protection Agency. Why do we need mosquito Is it necessary to spray When properly used by trained pro- • control programs? Q for adult mosquitoes in fessionals, insecticides do their job populated areas? and biodegrade quickly. Without control programs the • mosquito population would Yes. A well-planned, integrated flourish and cause potential As program involves stopping Are there methods other health and comfort problems. From mosquitoes in both the larval Q than the use of insecticides a health standpoint, mosquitoes and adult stages. Mosquitoes can for controlling mosquitoes? are known carriers of encephalitis, migrate up to 15 miles, which overrides malaria, and the yellow fever and local larval control efforts. This results Various control methods are dengue viruses. Mosquito-borne in the need for adult mosquito control. As constantly under review. One diseases cause more than one million effective approach involves deaths each year around the world. the use of mosquitofish, which can be Mosquito bites can also infect a pet stocked in mosquito breeding sites to with the deadly canine heartworm. Are the insecticides being feed upon the larvae. We also like to enjoy the outdoors. Q used for controlling Incidentally, studies have shown Well-planned municipal control pro- mosquitoes dangerous? that many homeowner methods such grams begin by eliminating mosquito as bug zappers, bird and bat houses, development in the early stage—the As No. Industry and government and citronella plants eliminate only a larval stage. testing procedures are so very small percentage of the mosquito advanced and so demanding population. In fact, many beneficial that it is virtually impossible to use a insects suffer the effects of these control product which could have an devices as well. adverse effect upon people, animals or plant life. What's more, the insecticides being used today are not only highly What can I personally do How can we best control effective,but also degrade rapidly. QO to helpcontrol mosquito Q mosquito breeding? devel• mosquito breeding? development? By identifying their breeding A Look for possible breeding • sites and preventing the lar- Do mosquito control 1 1• sites in your yard and com- vae from maturing to adults. Q insecticides pose any munity. Advise your local Preventing larval development into threat to the environment? officials of potential problems and let adult mosquitoes can be accom- the responsible government agency plished through carefully planned Insecticides are the most rigor- implement control procedures. If adult and implemented programs while A* ously tested of all chemicals. mosquitoes become a nuisance, meeting sound environmental stan- They meet stringent standards immediately notify your community dards. before they are registered for use by the leaders. r Exclusively formulated by: Clarke Mosquito Control Products Biomist adulticides are specially ® P.O. BOX 72197 formulated to fit into your Integrated Pest Management mosquito control program. Roselle, IL 60172 Biomist contains permethrin, a light stable 1-800-323-5727 synthetic pyrethroid that retains the rapid knockdown qualities associated with natural pyrethrins. Biomist is scientifically synergized to maximize the effectiveness of permethrin Distributed by: against mosquito populations yet maintains the lowest level of toxicity to man and other ZANUS CORPORATION non-target organisms. Biomist is a "no 1259 El Camino Real,Suite 134 ! odor" rapidly biodegradable formulation that MENLO PARK,CA. 94025 answers today' environmental concerns. Phone: (800)347-7783 ' If You Care. . . Biomist Fax: (415.)637-9927 Nab Oo"~e gzok4i� Uff When Biomist is Biomist, formulated with Biomist used at labelled Biomist eliminates synergized to the optimum level an EPA registered crop oil, rates is 80% biodegraded on environmental and the the effectiveness of Permethrin actually lubricates pumps plant surfaces within 24 hours. employee hazard of mixing. is increased four-fold. The high and increases equipment life. Chemical and microbial action This finished formulation can Used as directed Biomist combine to accelerate level of synergism delays the � be applied as delivered by air or onset of resistance and will not damage truck or degradation in the environment. ground ULU equipment. accelerates its breakdown in automobile paint. the environment. 10 • T" 0Field tests required for M �0 C agriculture registration demonstrated that permethrin Both field and wind applied at 10 times the ULU Resistance mechanisms Like other rethroids, which detoxify tunnel tests of Biomist show PY dosage rate had no adverse read reduced landing and field and laboratory tests have organophosphate insecticides greatly g shown that Biomist at sub-lethal effect on aquatic organisms in are different from those biting counts within 30 minutes. test ponds.doses causes mosquitoes to lose p affecting pyrethroid insecticides; their legs. This interferes with therefore, Biomist is effective LOWC4 successful flight and feeding. against organophosphate HAOVO-t-� j $�� resistant species. Biomist applied at Biomist is the least toxic � mosquito control rates will not / 'l�yti� Q ,�,� kill bees by residual action. Most y product registered with EPA for mosquito control with ground adult mosquito control. Oral LDS Biomist is not only ULU equipment is conducted in Biomist is odorless and to rats has been found to non-irritating. This enhances its effective against many mosquito the evening or night when use in public areas and be over 5,bod weig t. species but also controls both mosquitoes are most active and body weight. eliminates complaints. Y g Blackflies and biting and non- the bees are in their hives. biting midges. RainierAudabon Society P.O. Box 778 • Auburn, Washington 98071 (206) 939-6411 31 , 19 9 5 CrL -- -actLcv- -- --�- a-C,4� Lo- � • �yLJ c9-d� 11 I1�9,,� � , Rainier Audubon Society Y P.O. Box 778*Auburn, Washington 98071 (206) 939-6411 • Fax(206) 852-7766 VIOLET-GREEN SWALLOW NEST BOX PROJECT Thank you for providing a home I AP for the Violet-Green Swallows! The Violet-Green Swallow can be seen swooping By mid-October, the Violet-Green Swallows over most of our neighborhoods in the Spring and have returned to their wintering grounds Summer! Adept aerialists,Violet-Green Swallows which extend as far South as Central America. dart to catch flying insects. The average swallow consumes about 6,000 insects a day. Facts About Your Swallow Nest Box: The Violet-Green Swallow has dark upper parts Do not paint your nest box; natural wood is glossed with green and purple. It is pure white best for the birds. below with white rump patches which almost meet place 8-20' above the ground, preferably over the tail. The white of the throat extends well under the eaves on either the East or West up the sides of the neck and onto the face, side of your house. The nestbox should be located with an unobstructed approach. Breeding activity begins about early May. Their Keep your swallow boxes widely separated. preferred nesting sites are tree cavities and their populations have been impacted by the forestry Violet-Green Swallows are very clean. A practice of removing standing dead trees. few streaks of"whitewash" may appear on Fortunately, the Violet-Green Swallow will use nest the front of the nestbox. No maintenance is boxes! necessary since the birds will prepare the nestbox prior to nesting each season! Help the Violet-Green Swallows gather their The aluminum flashing on the top of the nesting materials by placing bits of cotton, feathers nestbox protects the swallows from from old pillows,etc. in the center of your lawn harrassment from other birds. where they can safely snatch them off the grass. Please contact us to let The female Violet-Green Swallow incubates the us know about the eggs, usually 4-6 in number, for 13-14 days. Both results of your Violet- the male and female care for the young which Green Swallow fledge in 16-24 days. nesting! Feathers for nesting material are available for $1/bag and pre-constructed Violet-green Swallow boxes are available for $16/each through Rainier Audubon (852-7766) Rainier Audubon Society Violet-green Swallow Nest Box Plans Baffle made from aluminium flashing (7" X 1 1 ") bent at 4" E 1/4 „ gap 7B11 rom front o roof Nail top of the f ront A only f rom side piece to allow the bot tom to open Very Important 1 ��8 that the opening " � is 7/ s" x 3" 4 .5 5 � I HH T T 3" 6 " B B l 9 11 A T c B = Sides A = Bott om ' C = Front �-- 9 • . T... 9 Dado cut 7 E D " 10' bevel for roof I E = Roof D = Back Contact A.J. Fisher, (2 06) 852-7766 Pre-constructed boxes are also available for more information for sale from Rainier Audubon for $16/each (including sales tax) Rainier Audubon Society: P. 0. Box 778, Auburn, WA 98071; (206) 939-6411 Smithsonian Migratory Bird Center HOW BIRDS KEEP OUR WORLD SAFE FROM PLAGUES OF INSECTS The Life of an Insect Caterpillars and pupae often match the outbreak by moving into the area. The color patterns of their surroundings,and abundance of birds at one of these Several species of insects,including the some even mimic the shapes of leaves or invasions can be as much as 80 times Western Spruce Budworm,Gypsy Moth, twigs. Other species hide in dead,curled above normal levels. Western Pine Beetle,and the Eastern leaves,on the undersides of green leaves, Spruce Budworm,experience population in fissures in bark,under leaf litter on the •The breeding season for birds occurs cycles in which populations of each species ground,or in flowers. Some have even during peak periods for insect remain low for several years and are then developed feeding patterns to avoid populations. During insect outbreaks, followed by population explosions,or predators, such as foraging at night, some birds will actually increase the outbreaks. During non-outbreak years, feeding in cryptic locations,or living and number of offspring they raise to take these insects are usually confined to small feeding under bark.Others snip off the advantage of the abundant food supply. areas where trees are subject to adverse leaves they fed on during the day in an conditions,such as drought,and are too attempt to trick birds that search for them •Birds like to feed large,juicy insects to weak to defend against the insects. on partially eaten leaves. their young. Relatively few insects survive the egg and young larval stages. Population outbreaks of some insect By feeding on large,late stages of species can have a devastating effect on the Birds are technologically caterpillars,and on pupae and adults, forest because the insects severely advanced, highly birds become a key force in depleting defoliate the trees or attack the bark. Vast insect populations. areas of forest have been killed during motivated, extremely outbreaks in the past. efficient,Cost-effective •Birds can alter their diets to feed almost exclusively on an insect pest during an The life cycle of outbreak insects follows a insect pest Controllers. outbreak,if it becomes advantageous for general pattern: rapid growth of the larva LZ them to do so. They can develop a search (caterpillar)-usually in June to mid-July- Birds Kill Bugs Dead image for the new prey and learn how to is followed by a pupal stage(cocoon) hunt for it more efficiently. during which the larva changes into an For all of the tactics insects have developed adult(moth,butterfly,beetle),and finally to avoid predation,they still face many •Along with developing a search image, the adult stage,when breeding and egg- species of birds that are highly adapted, birds can change their foraging locations laying take place. In some species the consummate insect-eaters: and adapt their behavior in response to pupal stage will last throughout the winter, an insect outbreak. For example,when a in others,the adult emerges in the same •Outbreak insects are often infected with vast quantity of insects is located in the summer. parasites. Many birds can identify the canopy of trees,many ground-or shrub- Dodging Death infected insects,and often select those dwelling birds may ascend to the canopy that are not parasitized. By preying only to feed. Similarly,during a hatch of on heathly individuals,birds add to the flying insects,birds that usually feed by Insects are subject to myriad threats effect of parasites in reducing insect plucking caterpillars off leaves may including adverse weather conditions, instead fly after the insects and capture disease,parasites,habitat destruction, populations. them in mid-air. insecticides,and predation by spiders,ants, .Birds can spread viral infections among beetles,mammals,reptiles,amphibians, insect pests. By eating beetles and their and birds. In the face of these odds, viruses and then defecating these viruses � however,insects have developed complex methods of surviving. along tree trunks, birds can spread �� '► infection to bark beetles in the same tree , Predator-avoidance strategies are as varied and throughout the forest. as the insects themselves. Some create •Birds are highly mobile and many species poisonous chemicals in their bodies,while may take advantage of a local insect others may be covered with spines. Fact Sheet No . 2 Smithsonian Migratory Bird Center Fact Sheet No.1 • Some foraging strategies of birds can predation on agricultural insect pests. In Insect outbreaks can destroy annually result in such substantial changes in some orchards, birds have been able to hundreds of millions of dollars of insect habitat that there is a resulting consume up to 98%of the overwintering agricultural and forest products. In 1921, increase in insect mortality. For instance, Codling Moths,and thus can successfully Edward Forbush wrote that"forest and by flaking bark off tree trunks, control the pest population. agricultural pests were reduced by 28% woodpeckers will expose bark beetles to by birds,resulting in savings of temperature extremes,loss of moisture, Helping Birds Help Us $444,000,000 in crop and timber losses." parasites,and predators,all of which The economic value of birds today is result in increased deaths. There is much we can do to promote the beyond our imagination. Their value is effectiveness of birds as predators of not just in their actual consumption of •Birds can affect the evolution of insects harmful insects,and thereby help ourselves insect pests,but also in their role in by increasing the cost to insects of financially and environmentally. keeping future outbreaks to a minimum. avoiding predators. Many of the predator-avoidance adaptations can For example,in Europe there have been decrease the insect's efficiency in feeding numerous successful programs to provide Further Reading and/or ability to lay the greatest possible nest boxes for cavity-nesting birds such as number of eggs. the Pied Flycatcher. These birds can Dickson,J.G.et al.,eds. 1979. The Role substantially reduce the insect pest of Insectivorous Birds in Forest Battling the Bugs population without the economic, Ecosystems. Academic Press, NY environmental,and health costs of Bird predation may play a critical role in pesticides. Holling,C.S. 1988. Temperate Forest reducing and/or maintaining low Insect Outbreaks,Tropical Deforestation populations of insect prey during non- Managing for snags(retaining standing and Migratory Birds. Mem.Entomol. outbreak years and in significantly dead trees)in a forest or woodlot also Soc. Canada 146:21-32. increasing the time between outbreaks. increases available habitat for woodpeckers Studies have shown that birds can eat up to and other cavity-nesting birds. These Morrison,M.L.et al.,eds. 1990. Avian 98%of budworms and as much as 40%of species are highly efficient predators of Foraging: Theory,Methodology,and non-outbreak species in eastern forests,and insects,and can have a marked effect on Applications. Studies in Avian Biology can alter the population cycles and lower insect populations. No. 13. Cooper Ornithological Society. the population peaks when an outbreak Allen Press,Inc. Lawrence,KS. does occur. One of the most promising forms of insect control is Integrated Pest Pschorn-Walker,H. 1977. Biological Increased numbers of birds in patches of Management(IPM),in which birds can Control of Insects. Ann.Rev.Entomol. forest with high insect pest density during a play a key role. The success and 22:1-22. non-outbreak year may result in the economic feasibility of these programs elimination of those insects,and can alter may depend on the number and diversity Takekawa,J.Y.et al. 1982. Biological the location and spread of a subsequent of birds in an area. Providing hedgerows, Control of Forest Insect Outbreaks: The outbreak. woodlots,streamside habitat,and shade Use of Avian Predators. Trans.N.Am. trees in an agricultural landscape can Wildl.Nat.Resour. Conf.47:393409. Orchards near woodlots tend to have more provide cover and nesting areas for birds. birds present,which increases the rate of Smithsonian Migratory Bird Center, National Zoo, Washington DC 20008 Feature Mythical Mosquito J Control Lee Mitchell Economics and science play impor- mosquitoes biting_peonle in they ra cis a zapper 14 hrs a day,in good weather tant roles in every mosquito control Biologists are concerned about the and bad,from the time of the first mos- program. By virtue of common sense high number of non-pest insects such quito hatch in the spring until the end and public overview we utilize person- as beetles and moths that are attracted of November. nel, equipment and insecticides in an and killed by bug zappers. Some of Even though we attempt to mosquito efficient manner to guide our pro- these insects are beneficial as natural adulticiding with insecticides as grams.We wisely encourage citizen in- biological controls on other insect specific as possible in terms of flow put and participation in our communi- pests and others are important in the rates,droplet size and time of applica- ty activities. How then do we respond food chain. Some people will operate Continued on page 19 to requests and comments regarding mosquito control methods that have lit- tle scientific support? Nature was a powerful opponent in Naturalists often claim that bats,pur- �' ,` a Q,, ' d ;. those days, and not least among her m dangers were the hordes of insects that ple martins and other insect-eating ; birds can adequately control mosquito t ka ,a plagued area residents. populations. Homeowners purchase TMt Campbell's bat tower was intended to electrocuting insect traps and elec- combat mosquito swarms for the early tropic insect re ellers b the developers of Temple Terrace,who were p y attempting to transform the groves of thousands.Industries advertise the in- � X �c .�- Temple(of course)oranges into a posh sect repelling qualities of all-purpose ?f3 - a ca surburban community.The Tower was lotions such as Skin-So-Soft and the ry M,wP designed to house more than 1,000 bats, hybrid Citrosa plant.Your response to imported from Texas, who were each such inquiries may cost you either y supposed to devour some 3,000 mos- public support or precious operating quitoes per night. funds as you sink money into a losing Despite a cavelike interior,nurseries proposition. for baby bats,and ribbed hanging racks, the bats never took to Campbell's tower. ELECTROCUTORS Instead they flew south, or wherever bats go, after being terrorized by local The ultraviolet or hlark lio�ht PIPr- teen-agers--leaving the developers of Temple Terrace with a $10,000 failure trocutor trans, also known as - (in 1924 dollars, mind you). Zappers° , Bug Blasters° and Big ��` ( ' Abandoned,the tower stood in a state Wackers° are probably the most - of disrepair until historic interest was popular choice by homeowners for revived in 1976, and plans were made mosquito control.One industry official Bat tower on Sugarloof Kq in south Florida.Photo by the city to purchase the tower's land estimates that up to 1.75 million bug by Doug Wassmer and refurbish the strange landmark. zappers are sold annually in this coun- Fifteen thousand dollars was granted try at upwards of$100 each These traps Nature, Man gang up to bring that year by the federal Department of down bat tower Housing and Urban Development to do attract and kill thousands of insects, restore the tower, but confusion over but often, as Gord Surgeoner and b P. Faber, Staff Writer who owned the land delayed the pro- Blair Helson showed in Canada 15 y 1• ff ject until a 1979 arsonist's fire that gut- years ago and Roger Nasci confirmed Precariously balanced on the muddy ted the structure put an end to the idea. in Indiana nearly a decade ago, mos- edge of the Hillsborough River just east quitoes comprise less than 5 percent of Tampa lie the ruins of a bizarre ex- (This article appeared in the July 11, 1981 of the catch. Of even greater impor- periment. Here, 57 years ago, .Dr. issue of the Tampa Times. Reprinted tance was the finding that these Charles Campbell's 36-foot bat tower here by permission of the Tampa devices did not reduce the number R failed to beat back the forces of nature. Tribune.) 18 WING BEATS, SUMMER 1992 Continued from page 18 ty to release the fresh aromatic are also some attractants in the com- citronella oil. The Citrosa plant does mercially available product and that % tion, many people still prefer the non- not bloom or reproduce naturally but the primary repellent component in ' discriminatory electrocutor traps and may be started with leaf cuttings. Skin-so-soft is better than DEET. The then blame the decline of favored Although there are numerous anec- mechanisms of how repellents work backyard songbirds on the use of dotes about the effective itrosa are not know. pesticides. Dr.George Craig,Jr.,of the there are no scientific st idi s th t suu- Most of us are well aware that the University of Notre Dame goes so far port the idea that the Citrosa plant are public expects and in some cases even as to call bug zappers a "fraud on the effective repellents. The plant leaves demands that insecticides should be public." must be touched or disturbed to very specific in their action. It is release the citronella aroma. As a humorous to note that Skin-So-Soft can REPELLING DEVICES house plant the lemony fragrance is also be used for 31 purposes,including quite pleasing,although the plant will removing chewing gum from hair, The word fraud can also be used to spread and grow to a height of several skin, and most-non-porous surfaces; describe a variety of mosquito repell- feet if it is not pruned. Plants sell for cleaning ink from skin and most-non- ing devices. At least ten studies in the about $12 and is tender below 45F. porous surfaces; cleaning ink from past 15 years have unanimously de- The proprietary bath oil Skin-So-Soft skin and most vinyl and painted sur- nounced these devices as having no will repel mosquitoes in the lab but, faces; cleaning paint brushes; remov- value whatsoever. Early versions - like citronella,it may or may not be ef- ing tar from car finishes without mosquito repelling devices use elec- festive on individual humans. The damaging paint and as a suntan oil. tromagnetic energy while more recent same applies to Culicoides biting designs produce high frequency midges. In laboratory trial, Rutledge PURPLE MARTINS aaund._ Some of these devices are and coworkers estimated that Aedes capable of being "fine tuned" by the aegypti was about 30 times more sen- An appraisal of the benefits of utiliz- purchaser,with instructions indicating sitive to the most commonly used in- ing purple martins and bats for mos- that the device can be adjusted until sect repellent DEET IN, N-diethyl-m- quito control offers fewer oppor- the correct frequency is found to repel toluamide)than to Skin-So-Soft. Jerry tunities for humor and may lead to mosquito pests.None of these devices Butler, however, has found that there Continued on page 20 have proven effective in repelling mos- quitoes when evaluated scientifically. COMPLETE . SPRAY . i T ere are many instances in which devices have been marketed that have little or no testing to support their ef- ficacy claims. It may also be noted that tem foraquatic weed management and • ' other corrosives. '' your in some of the product advertising, mosquito ht and today. Call us ' ll free: homeowners are urged to use these the built-in tote makes it to ' 67 devices to rid their home of pests handle. Thousands of these Units are in without the need to inhale "even one anotherfind field proven!systemwith these p• o n't CHEMICAL breath of poisonous spray." Suchqua price. CONTAINERS, statements play on public fears that in- ideal Box 1307 LAKE WALES, FL 33859-1307 secticides are harmful to humans and Phone : . : 40Florid, WATS 80 46 ; 67 should be avoided. CITROSA MOSQUITO FIGHTER") Weighs Less Than 28 lb's. Can Be Shipped Via UPS AND SKIN-SO-SOFT° Tote Tray With Handles The Citrosa "Mosquito Fighter" 15 Gallon ` plant and Avon's Skin-So-Soft bath oil Poly Tank are also marketed for their mosquito repelling qualities. Citrosa was genetically created by crossing tissue cu tures of an rican geranium wi �'o •'"""� "" 56 psil the Grasso China.The grass contains citronella oil,which has been used for �````- -y`° many years as the active ingredient in 18"Brass Wand&Nozzle Gun mosquito repellent coils and candles. Also available in 35, 50 and 100 gallon models The geranium gives the plant the abili- TOTALLY PORTABLE! ORDER TODAY! WING BEATS, SUMMER 1992 19 r Continued from page 19 houses for insectivorous birds to be safe and effective. Although specifically for the purpose of mos- ultraviolet electrocutor traps will at- quite heated debates. It has been quito control, we should build them tract and kill mosquitoes,they are often known for many years that purple mar- simply to attract these interesting birds misused and kill large numbers of in- tins consume large numbers of flying for their esthetic and educational nocuous insects. Vertebrate predators sects. Proponents of the value of pur- value. It is a mistake to promote the such as purple martins and bats will ple martins have often used the state- welfare of those wildlife species that ment by Wade that "a purple martin only seem beneficial to man in some , will eat 2,000 mosquitoes in a day."He obvious way. also stated that 10,000 to 14,000 mos- � N. uitoes could be consumed per day BATS f when mosquitoes are plentiful. All of { ' Wade's values were non-scientific More recently some naturalists have estimates based on his belief that mar- become interested in the welfare of F .. tins had an extremely rapid digestive bats and have noted the value of insec- process and metabolism. He reasoned tivorous species in controlling mos- that an adult purple martin would have quito populations. They have subse- to consume its body weight each day quently recommended the construc- in flying insects in order to survive. tion of bat houses for the protection Thus, if an average adult martin and propagation of those species that weighted 4 oz., this would be the have been evicted from caves or human equivalent of 14,000 mosquitoes.Ac- residences.That such an idea is a new tually,Wade's math was faulty because one may be quickly refuted by referr- he greatly overestimated the weights of ing to the literature. During the 1920's an individual mosquito and martin several large bat towers were con- and many more would have to be con- structed near San Antonio, Texas and ;4 ' sumed to provide the necessary Key West and Tampa,Florida with the Purple Martin with preferred prey. nutrition. intent of controlling malarial mos- Wade did not analyze the stomach quitoes with high numbers of insect- consume mosquitoes and should be contents of martins but did recognize eating bats. Mosquito populations considered as part of an integrated that their diet included flies, were not reduced but the large ac- pest management program. A public dragonflies,beetles, moths, locusts and cumulations of guano was sold at a education program should accompany other bugs in addition to mosquitoes. profit. the use of artificial cavity-type houses Unfortunately, many naturalists have The bats of temperate regions re- for the promotion of insectivorous bats failed to differentiate between Wade's main almost exclusively insectivorous. and purple martins. Predators can not theories and scientific fact. As with martins, bat food consists totally replace source reduction and Exhaustive studies of the diet of pur- mainly of beetles, wasps, ants, flies, chemical control. Electronic mosquito ple mart sni by several ornithologist in- stoneflies, mayflies, moths and repellers have a dismal performance dicate that while mosquitoes are a part grasshoppers. Mosquitoes make--up record and should be vigorously of the diet they eat many more wasps, less than 1 percent of their diet discouraged. The Citrosa Mosquito ants, house flies,crane ies, stinkbugs,_ afffioug the percentage may a ig er Fighter plant has no proven merit and tree hoppers,beetles,butterflies,moths when mosquitoes are abundant. The research is needed to demonstrate any ann ragontlies. osquitoes make up evidence from stomach analysis and mosquito repelling qualities that it may Less than three ercent oTtheir diet. feces examination show that insec- possess. Personal protection from mos- After alT it takes a lot of mosquitoes to tivorous bats do help regulate some in- quitoes is best gained by the proper use add up to one dragonfly. sect populations, both beneficial and of DEET and other topical repellents, Ornithologist James Hill is founder pest species — but not mosquitoes. including Skin-So-Soft. and director of the Purple Martin Con- However, bats are worthy of our pro- servation Association. He is especial- tection regardless of their capacity or ly anxious to dispel the longstanding proclivity to consume pest or vector Lee Mitchell is a Biologist notion that a single martin eats populations of mosquitoes. with the lbledo Area Sani- thousands of mosquitoes in one day. tary District, 5015 Stickney According to Hill, "The number of SUMMARY Avenue,Toledo,Ohio 43612; mosquitoes that martins eat is extreme- 419/726-7891; FAX: 419/ ly insignificant, and they certainly It is our responsibility to educate the 726-7721. don't control them." Rather than erect public about mosquito control and to martin houses and other cavity-type utilize those methods that are known 20 WING BEATS, SUMMER 1992 273 nd Skeeters pies p . are th-iekebe's By Janice Podsada from 100 to 400 eggs at a time.Over after your thrashing significant other. o e Valley Daily News a month's time, a female will lay as The safest way to keep mosquitoes to rc Nocturnal singing in your ear? many as 4,500 eggs.And for her eggs away is to spray repellants such as Off Mosquito hict$ rack g(More than likely it's not the muse,but to develop,the female mosquito must or 6-12 on your clothes, but not on Ms. Mosquito looking for a meal. procure a blood meal,which is like- your skin,Antonelli said. ■There are 3,000 "This is a particularly bad year for ly to come from an unsuspecting arm So how do you rid your yard of species of mosquitoes in s�� mosquitoes,"said Arthur Antonelli, or leg. mosquitoes? the world. fast entomologist with Washington State "They like us because we're b 0 Local species number are Flatten tin cans.Punch holes in old University Cooperative Extension in and we give off lots of carbon diox- tires.Fill in tree holes.Don't kill drag- about 100. By Mike Archbold Puyallup. ide,"Antonelli said. "Animals with onflies.Buy a school of goldfish. 0 Only the females bite. Valley pally News Blame it on the rain,Antonelli fur don't seem to suffer so much." Without a plentiful source of 0 The swelling around AUBURN—The stag. said. And don't expect much in the Scientists are not sure why some standing water, mosquitoes can't the bite is caused by an racing officials took a f way of relief this month. humans are more attractive to mos- breed.And what constitutes standing allergic reaction to the approach Tuesday "Until the sun fries up all those quitoes than others. water doesn't necessarily have to be mosquito's saliva, which it Muckleshoot Tribe's bi, ly standing ponds, the population of "I don't have any scientific data on a lake a swamp or a pond. injects under a human's over operations of the and mosquitoes will continue to rise," this,but it seems women complain of The back yard,for instance,can be skin to keep blood flowing. racetrack in Spokane. Antonelli said. more bites than men,"Antonelli said. a lovely nursery for a female mos- 0 Mosquitoes do not The tribe also expec Mosquitoes have been biting, Some researchers say the more quito's eggs. And the little blood- spread AIDS, but they can next couple weeks to beg bloodletting and breeding since April, you flail,the more carbon dioxide you suckers stick close to home, rarely cause encephalitis in rare casting racing from but July is typically the month when exude,which only makes you a more traveling more than a mile from their cases. Emerald Downs. the"skeeters"peak. attractive meal. Thus the the best place of birth. ofHealtheattle-King County Department By a 2-1 vote,the her! Depending on the species, a thing to do may be to remain calm— Some species will hatch in three to commission tentatively l female mosquito can lay anywhere in hopes the mosquitoes will go See MOSQUITOES, A6 a public Bearing Jul Spokane on the tribe's ap. to start live racing at the �n Rural police calls track as soon as Sept. i25. t Like a page from ����t Commission Chair 1 Shinpoch of Renton obj 06 rising, response moving that fast on an apl p se that was only received by I 10 � " t�' Ar yd 6 y ission July 1,but she w 31 n mission by commissioner: " °t Seabeck of Spokane and 20 y times slowiw 4 { Plut Of SeatilP. )0 By Chris Norred p. + '' Sea beck wanted the c Valley Daily News sion to rule on the appl A new study of calls to King County police offers proof k;� °' Tuesday but P1 ut agree of what many citizens already suspected—police get more *f * ' :;r Shinpoch that a final decis calls from the rural areas and respond to them slower than t` take more time. they did five years ago, Mr After the meeting at King County Sheriff James Montgomery said Tuesday City Hall, Shinpoch sai are a lot of unanswered qt :8 the results of the study are not surprising, but they help 1 i define exactly how the department must improve. t � I" in the application but she Emergency response remains relatively swift,but the r4Mr' I, think the decision process 12 response to nonemergency calls in the rural areas of King fit " �z. t" take long. .8 County has slipped significantly since 1991,according to "� t She would also favor the a .. the study. .k`' m"F.n:<� }r x ,. ttllttn �f a nrrhlir• h��r;nr ... J ava "aa.........--I- I atluuulitJ ullul.l " ul to make it a central election-year issue. final vote and stress its importance. 1 the date for raising the wage to I of production workers in `•the invisible Americans who "If you are looking for a straw in the $4.75 and until Jan. 1, 1998 for insti- all private,ndustries. Tuesday to overhaul have been left out and left behind wind"to see how political fortunes tuting the full$5.15,both six months Average of first six troubled retirement sy months. The bill, offered b were recognized today by the U.S. are blowing this year, "look no fur- beyond the House-set dates. Smith, R-Mich.,with Senate," said Edward Kennedy, D- ther than this vote,"he said. The House bill allows for a 90-day $4.24 I, ment of some seniors Mass.,a leading proponent. The Clinton administration has period when teenagers can be given a % r would delay the tors . The bill was part of a package of tax campaigned vigorously for the wage "subminimum"or"training"wage of wool age,y he reti l breaks aimed mainly at business that increase and has chided Bob Dole, $4.25.Bond would double that period ment ions fc passed the House by 281-144 in a sim- President Clinton's likely opponent and make it apply to all new workers. p ilar version on May 23.The two cham- in November,for not speaking out in His amendment was defeated 52- future retirees, cut tl hers still must work out differences in behalf of it.The minimum wage issue 46,with five Republicans joining all r additional benefit fc the tax section of the legislation. bedeviled Dole's final days as Senate 47 Democrats in opposing it. Sen. r S1so married all necouwl s, a e Sen.Majority Whip Don Nickles, majority leader, with Kennedy and James Jeffords,R-Vt., who joined e q y R-Okla., said he might try to block other Democrats blocking movement GOP Sens.Ben Nighthorse Campbell state and local goven the House-Senate negotiating confer- of other bills because of GOP reluc- of Colorado, Arlen Specter of r ment workers to jo ence until Democrats give ground on tance to take up the minimum wage. Pennsylvania, Alfonse D'amato of i Social Security. stalled health care legislation. But Dole's campaign, in a statement, New York and Mark Hatfield of "Social Security '38 '45 I'56 63 l'68 '75 ' 78 '80 '90 96 Senate Democratic leader Tom said he had made clear his support of Oregon in voting against it,voiced - ss , Dept.of °�s '7s ©f '91 operating today is n Daschle of South Dakota said a raise in the wage and said Clinton concern that businesses would fire L5mpio U.S.0 nardsAdLabor, solvent," Smith told g Employment Standards Admrnistrgtion I a Republicans would obstruct final pas- had ignored the issue in his first two workers after six months to avoid — -- -- AP/Carl Fox news conference. `T] sage"at their own peril." years and was now"playing maxi- paying the minimum wage. latest Social Administrationn rep repc shows that Soci Security will be pay Scott Woodbury, project manager TRACK than it is taking in fron MOSQUITOES with Renton's surface water utili- How to kill `erg by the year 2012." Continued from Al ty. Continued from Al .Sen. Alan Simpsc To eliminate breeding frequent critic of the r Sprayers use low-volume, gas- p and racing secrets Ted Martin,who tem, said "anyone laces at home: g secretary powered foggers to fumigate the area ®Drain gutters and water has been involved in Washington under 40 is doomed"t five days,and like mom,begin biting with adulticide,which kills adult mos- g man from under homes. horse racing for ears. tem undergoes radica the moment they emerge. quitoes,but not the larvae,which live y y Mosquitoes can breed in the bird in water. E Change water in bird If the application is approved,the tribe At a separate new bath, the dog dish, in a tin can or on Yet in spite of the deadly mist- baths at least twice a week'. would like to operate 92 race days House Majority I I�'Fill or drain puddles and � t.25andMarch30.Arequest Armey, R-Texas, it a sheet of wet plastic. ing,chances are good the mosquitoes � Homeowners who have backyard will continue to plague nearby resi- ditches near the home. for those dates would also have to be changing Social Secc ponds should keep them stocked with dents until the end of July,Woodbury 0 Drill drain holes in the approved by the racing commission. on the table "after goldfish, since the fish eat mosquito said. bottom of old tires used as I Ziegler said the tribe is willing to taken their beati larvae—as do dragonflies, said Dan So far,the area around Talbot Hill planters. share race dates with Yakima Meadows November elections. Moran, environmental health spe- hasn't been hit hard,he said. 0 Pay particular attention racetrack in an effort to continue live That would be thf cialist with the Seattle-King County "But then,I'm out there in the day to such gardening aids as racing in Eastern said,"that we can ha- Department of Public Health, and they may be biting at night," sheets of discarded, crumpled Washington. The tlz'ibe responsible,forward- plastic (plastic mulch). These P I a f a i r term policy discussic Or try lighting a citronella candle, Woodbury said. p �p y Moran said. But only use them out- "We hope it's due to spraying.But catch water easily and create opened the would Zl t0 sacred-cow subject doors. then again,some of us are saying,the breeding sites. track June 29 Operate 92 Security." In an effort to keep wetlands worst of the season may not be here Source: Seattle-King county Department for training and race days Although Socia p more than 236 y rarely discussed on tl from becoming major breeding yet,"Woodbury said. ponds, the city of Renton has been When it comes to mosquitoes, horses are now between campaign trail, it i spraying areas near Panther Lake, Antonelli had this piece of wisdom: the itch,remember it could be hornet at the track. ,Sept. 25 and gain some attention up the hill from the valley floor and "Live with it." season—which,by the way, arrives Ziegler told arch 30. mer when an advisor into the brushy hillside area, said And if that advice doesn't soothe on gossamer wings next month. the commis- ommends the syster sioners that time is critical if the track is to be run- County," said City Administrator "It's vital to the business com- ping this year. , RUNWAY John McFarland of the Tukwila munity." The application calls for the track to rn,,,,,.;i nnnncltlnn "Mare take- Auburn is officially neutral,but continue to lose money for four years B10MIST' For Application Only by Public Health Officials and Trained Personnel of Mosquito Abatement Districts and Other Mosquito Control Programs. For Use Outdoors As An Ultra-Low Volume (U.L.V.) Application to Control Adult Mosquitoes in Residential and Recreational Areas. Also For Use Against Biting and Non-Biting Midges and Blackflies. CLARKE Precautionary Statements U.L.V. Nonthermal Aerosol (Cold Fog) Application: To control Mosquitoes, HAZARDS TO HUMANS AND ACTIVE INGREDIENTS: Midges and Blackflies,apply BIOMISTo 3+15 ULV using any standard U.L.V.ground DOMESTIC ANIMALS Permethrin(3-Phenoxyphenyl)methyl(+)cis, applicator capable of producing a nonthermal aerosol spray with droplets ranging in trans-3-(2,2-dichlorethenyl)-2,2-dimethyl- size from 5to 30 microns and a mass median diameter(MMD)of 10 to 15 microns.Apply CAUTION cyclopropanecarboxylate ...................... 3.00% the product undiluted at a flow rate of 3.00 to 18.00 fluid ounces per minute and an Wash thoroughly after handling.Avoid breathing of mist.Do not contaminate food or Piperonyl Butoxide,Technical average vehicle speed of 10 mph. If a different vehicle speed is used, adjust rate feed products. Equivalent to 80%(butylcarbityl) 0044 to .0264 These o pounds of Pies eeronylaButoxlent ide00er8acre.Va to.005 ry flow unds ra rate according rmethrin and to STATEMENT OF PRACTICAL TREATMENT (6-propylpiperonyl)ether and vegetation density and mosquito population.Use higher flow rate in heavy vegetation If Swallowed:Call a physician or Poison Control Center immediately.Gastric lavage is 20%related compounds........................ 15.00% or when populations are high.An accurate flow meter must be used to ensure the indicated if material was taken internally.DO NOT INDUCE VOMITING.Vomiting may INERT INGREDIENTS............................ 82.00% properflow rate.For proper applic on,mountthefog applicator so thatthe nozzle is cause aspiration pneumonia. 100.00% at least 41h feet above ground level and directed out the back of the vehicle.Failure to If Inhaled:Remove victim to fresh air.Apply artificial respiration if indicted. Contains 0.225 pounds of Permethrin and follow the above directions may result in reduced effectiveness.Aerial applications If On Skin: Remove contaminated clothing and wash affected areas with soap and 1.125 pounds of Piperonyl Butoxide per gallon. shoo d be edge by suitable aerial U.L.V. equipment an altitude 0 0fft. and a forwfd speed of 150 miles per hour,achievi n n effective swath widthth off 500 ft.Flow unces water. rate should be set at 455 fluid o peC A (3.0 fluid ounces of BIOMIST,3+15 If In Eyes:Flush eyes with plenty of water.Get medical attention if irritation persists. ULV per acre i ENVIRONMENTAL HAZARDS CAUTION This product is extremely toxic to fish. Do not apply directly to water or wetlands (swamps,bogs,marshes,and potholes).Drift and runoff from treated areas may be KEEP OUT OF REACH OF STORAGE & DISPOSAL hazardous to aquatic organisms in adjacent areas.Do not contaiminate water when disposing of equipment washwaters.Apply this product only as specified on this label, Do not contaminate food,feed or water by storage or disposal. This product is highly toxic to bees exposed to direct treatment on blooming crops or C LD REN weeds.Do not apply this product or allow it to drift to blooming crops or weeds while STORAGE:Do not store at temperatures below 40°F(4.5°C).If this material has bees are actively visiting the treatment areas. been been exposed to temperatures below 40°F(4.50C),there may be precipitation. Check for IfPHYSICAL OR CHEMICAL HAZARDS before using.DO NOTtUSE OPENdent FLAME.rm to 80°F(26.5°C)and thoroughly mix Do not use or store near heat or open flame.Flashpoint minimum of 300 F, MANUFACTURED BY PSTICID DISPOSAL:Wastes waste disposal facility from the use. this product may be DIRECTIONS FOR USE diposed of It is a violation of Federal Law to use this product in a manner inconsistent with its'labeling. CLARKE MOSQUITO CONTROL CONTAINER DISPOSAL:Triple rinse(or equivalent).Then offer for recycling CONDITIONS and RATES to USE PRODUCTS CO., INC. or reconditioning,or by state and dispose o in a sanitary landfill,or by other procedures approved b state and local authorities. for MOSQUITO CONTROL 159 N. GARDEN AVENUE Permethrin/PBO Application Rates Ft.oz.Blomist,3+15 ROSELLE, ILLINOIS 60172 pounds/acre Ft.oz./Min. per acre ZANUS CORPORATION 5MPH 10MPH 15MPH 0.005/0.0264 9.0 18.0 27.0 3.0 E.P.A. EST. No.83291L01 1259 El Camino Real, Suite 13 0.00264/0.0132 4.5 9.0 13.5 1.5 EPA. Reg. No.8329-33 MENLO PARK, CA. 94025 0.00088/0.0044 1.5 3.0 4.5 0.5 Do not apply this product within 100 feet of fish bearing areas.BIOMISTo 3+15 ULV is Phone: (800) 347-7783 ' • recommended for application as an ultra low volume(U.L.V.)nonthermal aerosol(cold NET CONTENTS Fax: (415)637- fog) to control adult mosquitoes in residential and recreational areas and other non-cropland areas where these insects are a problem.For best results treat when • • mosquitoes are most active and weather conditions are conducive to keeping the fog NOTICE:Seller makes no warranty,expressed or implied concern- • • close to the ground,e.g.cool temperatures and wind speed not greater than 10 mph. indicated on the label.Buyer • Application during the cool hours of the night or early morning is usually preferable. assumes all risk of use and/or handling mg the use of this product other than indic is this material when use Repeat treatment as needed.Do not apply this product within 100 feet(30 meters)of lakes and streams.Do not allow spray treatment to drift on pastureland,cropland, and/or handling is contrary to label instructions. • ♦ , poultry ranges,or water supplies. sisa 10MI T"' 1 + 66 LILV For Application Only By Public Health Officials and Trained Personnel of Mosquito Abatement Districts and Other Mosquito Control Programs. An All Temperature, Quick Knockdown, Low O�or, Non-Corrosive, Synthetic Pyrethroid for Control of Adult Mosquitoes in Residential, and Recreational Areas. Also For Use CLARKE Against Biting and Non-Biting Midges and Blackflies. Precautionary Statements BIOMIST 31+66 ULV is recommended for application as an ultra low volume For proper application.mount the fog applicator so that the nozzle is at least ACTIVE INGREDIENTS: (U.L.V.)nonthermal aerosol(cold fog)to control adult mosquitoes in residen- 411,feet above ground level and directed out the back of the vehicle.Failure to HAZARDS TO HUMANS AND tial and recreational areas where these insects are a problem,such as but not follow the above directions may result in reduced effectiveness Aerial DOMESTIC ANIMALS Permethrin(3-Phenoxyphenyl)methyl 11-1 cis, limitedto parks,campsites,woodlands,athletic fields,golf courses.residential applications should be done by suitable aerial U.L.V.equipment capable of trans-3-(2.2-dichlorethenyl)-2.2-dimethyl- areas and municipalities, gardens, playgrounds, recreational areas and producing droplets with an MMD of 50 microns or less with no more than 2 5 CAUTION cyclopropanecarboxylate ...................... 31.28% overgrownwasteareas.Do not apply this product within 100 feet(30 Meters)of exceeding 100 microns. Flow rate and swath width should be set so as to May be fatal if swallowed Harmful if absorbed through skin or inhaled Avoid Piperonyl Butoxide.Technical takes and streams. Do not allow spray treatment to drift on pastureland, achieve.33 to 1.0 fluid ounces of BIOMIST 31+66 ULV per acre BIOMIST y g Pi Y cropland, poultry ranges, or water supplies For best results treat when 31+66 ULV may also be diluted with a suitable solvent such as mineral oil and contact with skin. eyes or clothing. Avoid breathing spray mist. Wash Equivalent to min.80%(butylcarbityl) mosquitoes are most active and weather conditions are conducive to keeping applied by aerial ULV equipment so long as 1.0 fluid ounces per acre of thoroughly with soap and water after handling and before eating or smoking. 16-propvlpiperonyl)ether and the fogg close to the ground,e.g.cool tempperatures and wind speed not greater BIOMIST 31+66 ULV is not exceeded.Both aerial and ground applications Remove contaminated clothing and wash before reuse. 20°ro related compounds........................ 66.00% than Vph.Applications during the cool hours of the night or early morning is should be made when wind is less than 10 MPH ° usually preferable.Repeat treatment as needed. IN FLORIDA: Do not apply by aircraft except in emergency situations and STATEMENT OF PRACTICAL TREATMENT INERT INGREDIENTS ............................ 2.72/° U.L.V.Nonthermal Aerosol(Cold Foy�))Application:To control Mosqui- with the approval of the Florida Department of Consumer Services 100.00% toes,Midges and Blackflies,apply BIOW)31+66 ULV using any standard IF SWALLOWED. Call a physician or Poison Control Center Drink one or two Contains petroleum distillates. U.L.V. ground applicator capable of producing a nonthermal aerosol spray glasses of water and induce vomiting by touching the back of throat with Contains pounds of Permethrin and pounds with droplets ranging in size from 5to30 microns and amass media iameter STORAGE & DISPOSAL finger.Do not induce vomiting or give anything by mouth to an unconscious p p MMD)of 10 to 20 microns.Apply the product undiluted at r f 1.0 to Do not contaminate water,food or feed b stora a or dis osal. person of Piperonyl Butoxide per gallon. MO fluid ounces per minute at an average vehic 1 h. if a y g p different vehicle speed is used, ad u co These s are PESTICIDE STORAGE AND SPILL PROCEDURES:Store upright IF ON SKIN: Remove contaminated clothing.Wash with plenty of soap and CAUTION equivalent to 0.0035 to 0.021 ounds a unds at room temperature.Avoid exposure to extreme temperatures.In case of water Get medical attention if irritation persists. of Piperonyl Butoxide per ary f ate rdi do nsit spill or leakage, soak up with an absorbent material such as sand. and mos u to population her a egetation sawdust,earth.fuller's earth,etc.Dispose of with chemical waste IF INHALED Remove victim to fresh air.If not breathing give artificial respira- populatio re high.Ana r ow u h r p tion.preferably mouth to mouth Get medical attention immediately. KEEP OUT OF REACH OF ffowrate. mist^31+66 Is appli asuitable PESTICIDE DISPOSAL:Wastes resulting from the use of this product CHILDREN solvent su hs mineral i to ceed the maximum may be disposed of on site or at an approved waste disposal facility ENVIRONMENTAL HAZARDS pounds of ' tive in red n in the first column of the This product is extremely toxic to fish and aquatic invertebrates.Do not apply previous to e.The g char epresent some suggested dilution and CONTAINER DISPOSAL:Triple rinse (or equivalent) then otter for directly to water.to areas where surface water is present or to intertidal areas application r$( U.L.V.applications.If an alternate dilution rate is recycling or reconditioning, or puncture and dispose of in a sanitary below the mean high water mark.Do not apply when weather conditions favor used.adjust It a accordingly. landfill,or by other approved state and local procedures. drift from treated areas-Drift and runoff from treated areas may be hazardous FOR A 1:2 BIOMIST, 31+66 ULV/SOLVENT DILUTION RATIO CONTAINERS ONE GALLON AND SMALLER: Do not reuse con- Mix one(1)part BIOMIST- 31+66 with two(2)parts solvent and apply at the tainer. Wrap containers in several la newspaper to aquatic organisms in neighboring areas.Do not allow spray treatment to following rates. P layers of news a er and discard in drift on pastureland, cropland, poultry ranges or water supplies Do not �; `MANUFACTURED BY trash. contaminate water when disposing of equipment washwaters Permethrin Application Rates Fl.oz.finished spray pounds/acre Fl.oz./Min. per acre CONTAINERS LARGER THAN ONE GALLON:Metal Conlainers- PHYSICAL OR CHEMICAL HAZARDS CLARKE MOSQUITO CONTROL 5MPH 10MPH 15MPH Triple rinse or equivalent.Then offer for recycling or reconditioning. or Do not use or store near heat or open flame Ftashpoint minimum of 300,F PRODUCTS, INC. 0.003 3.5 3.0 4.5 1.5 puncture and dispose of l u sanitary landfill. or in other procedures 159 N. GARDEN AVENUE 0.0035 1.5 3.0 4.5 0.5 approved by state and local authorities.Plastic Containers-Triple DIRECTIONS FOR USE 0.00175 0.75 1.5 2.25 0.25 equivalent.Then offer for recycling or reconditioning, or puncture and ROSELLE, ILLINOIS 60172 dispose of in a sanitary landfill,or by incineration.or if allowed by state It is a violation of Federal Law to use this product in a manner FOR A 1:4 BIOMIST, 31+66 ULV/SOLVENT DILUTION RATIO and local authorities, by burning. If burned. stay out of smoke. Then inconsistent with its'labeling. Mix one(1)part BIOMIST- 31+66 with four(4)parts solvent and apply at the dispose of in a sanitary landfill or by other approved state and local E.P.A. EST. No.8329IL01 following rates. I procedures. CONDITIONS and RATES to USE Permethrin Application Rates Fl.oz.finished spray EPA Reg. No.8329-43 pounds/acre Fl.oz./Min. per acre for MOSQUITO CONTROL 5MPH 10MPH 15MPH IN CASE OF EMERGENCY,CALL INFO TRACI-800-535-5053 Permethrin Application Rates Fl.oz.Biomist- 31 66 0.007 5.0 10.0 15.0 1.6 pounds/acre Fl.oz./Min. per acre NET CONTENTS 0.0035 2.5 5.0 7.5 0.8 SMPH 1oMPH 15MPH 0.00175 125 2.5 3.5 0.4 0 021 30 6.0 9.0 1 0 FOR A 1:8 BIOMIST, 31+66 ULV/SOLVENT DILUTION RATIO 00105 1.5 3.0 4.5 0.5 NOTICE:Seller makes no warranty,expressed or implied concern- Mix one(1)part BIOMIST-31+66 with eight(8)parts solvent and apply at the 00035 0.5 1.0 1.5 0.16 ing the use of this product other than indicated on the label.Buyer following rates. � assumes all risk of use and/or handling of this material when use Permethrin Application Rates Fl.oz.finished spray ' and/or handling is contrary to label instructions. pounds/acre Fl.oz./Min. per acre 5MPH 10MPH 15MPH 0.007 9.0 18.0 27.0 30 0.0035 4.5 9.0 13.5 1 5 • . 0.00175 2.25 4.5 6.75 0.75 y 10MI T512 • • ULV For Application Only By Public Health Officials and Trained Personnel of Mosquito Abatement Districts and MEN Other Mosquito Control Programs. An All Temperature, Quick Knockdown, Low Odor, Non-Corrosive, Synthetic Pyrethroid for Control of Adult Mosquitoes in Residential, and Recreational Areas. Also For Use CLARKE Against Biting and Non-Biting Midges and Blackflies. Precautionary Statements BIOMIST®12+60 ULV is recommended for appplication as an ultra low volume For roper application,mount the fog applicator so that the nozzle is at least HAZARDS TO HUMANS AND ACTIVE INGREDIENTS: (U.L.V.)nonthermal aerosol(cold fog)to control adult mosquitoes in residen- 41h feet above ground level and directed out the back of the vehicle.Failure to Permethrin INGREDIENTS: nox hen I)meth I(�)cis, tial an dd recreational areas where these insects are a problem,such as but not follow the above directions may result in reduced effectiveness. Aerial DOMESTIC ANIMALS yp y y limited to parks,campsites,woodlands,athleticfields,golf courses,residential applications should be done by suitable aerial U.L.V.equipment capable of trans-3-(2,2-dichlorethenyl)-2,2-dimethyl- areas and municipalities, gardens, playgrounds, recreational areas and producing droplets with an MMD of 50 microns or less with no more than 2.5% CAUTION cyclopropanecarboxylate...................... 12.00% overgrownwasteareas.Donotapplythisproductwithin100feet(30Meters)of exceed ingg 100 microns. Flow rate and swath width should be set so as to h skin.Avoid contact with Piperonyl Butoxide,Technical lakes and streams. Do not allow spray treatment to drift on pastureland, achieve 1.0 to 3.0 fluid ounces of BIOMISTe 12+60 ULV per acre.BIOMIST� Harmful if swallowed,inhaled or absorbed through cropland, poultry ranges, or water supplies. For best results treat when 12+60 ULV may also be diluted with a suitable solvent such as mineral oil and skin,eyes or clothing.Avoid breathing spray mist.Wash thoroughly with soap Equivalent to 80%(butylcarbityl) mosquitoes are most active and weather conditions are conducive to keeping apppplied by aerial ULV equipment so long as 3.0 fluid ounces per acre of and water after handling. Remove contaminated clothing and wash before (6 propylpiperonyl)ether and the fogg close to the ground,e.g.cool temperatures and wind speed not greater BIOMIST®12+60 ULV is not exceeded. Both aerial and ground applications reuse.Do not contaminate food or feed products. 20%related compounds........................ fi0.00% than 10mph.Applications during the coo hours of the night or early morning is should be made when wind is less than 10 MPH. o usually preferable.Repeat treatment as needed. IN FLORIDA: Do not ap ly by aircraft except in emergency situations and INERT INGREDIENTS............................ 28.00% U.L.V.Nonthermal Aerosol Cold F Application:To control Mos ul p STATEMENT OF PRACTICAL TREATMENT ( � Pp q �- with the approval of the Florida Department of Agriculture and Consumer If Swallowed: Call a physician or Poison Control Center immediately.Do not 100.00% toes,Midges and Blackflies,apply BIOM ®12+60 ULV using standard Services. induce vomiting because of aspiration hazard. Contains petroleum distillates. U.L.V.ground applicator capable of producing a n of spray Contains 1.0 pounds of Permethrin and 5.0 pounds with droplets ranging in size from 5to30mi rons a diameter STORAGE & DISPOSAL If Inhaled: Remove victim to fresh air.If not breathing give artificial respira- of Piperonyl Butoxide per gallon. (MMD)of 10to 20 microns.Apply t di at a w of 3.0 to tion,preferably mouth-to-mouth.Get medical attention. 16.00 fluid ounces per eat eh f ph. If a Do not contaminate water,food or feed by storage or disposal. CAUTION different vehicle sppee t cc hes t If On Skin: Remove contaminated clothing. Wash with plenty of soap and equiva to0.0035to and a 0175 PESTICIDE STORAGE AND SPILL PROCEDURES:Store upright water.Get medical attention if irritation persists. of Pipe f Butoxide ry rate r ti ensity at room temperature.Avoid exposure to extreme temperatures.In case of told mo 'to populat' Us fie w r h e ation or when spill or leakage, soak up with an absorbent material such as sand, Note to Physician: Product contains a petroleum distillate.Gastric lavage is KEEP OUT OF REA OFpulati arehigh. be used to ensure the proper sawdust,earth,fuller's earth,etc.Dispose of with chemical waste. indicated if material was taken internally. Vomitr may cause aspiration w rat sto 12 applied by diluting with a suitable PESTICIDE DISPOSAL:Wastes resulting from the use of this product pneumonia. (� L vent s a d and pptying so as not to exceed the maximum unds o nt per acre as shown in first column of the previousmay be disposed of on site or at an approved waste disposal facility. ENVIRONMENTAL HAZARDS le.The in charts represent some suggested dilution and application CONTAINER DISPOSAL: Triple rinse (or equivalent) then offer for esfor ground U.L.V.applications.If an alternate dilution rate is used,adjust recycling or reconditioning, or puncture and dispose of in a sanitary This product is extremely toxic to fish and aquatic invertebrates.Do not apply w rate accordingly. landfill,or by other approved state and local procedures. directly to water,to areas where surface water is present or to intertidal areas FOR A 1:2 BIOMISTo 12+60 ULV/SOLVENT DILUTION RATIO CONTAINERS ONE GALLON AND SMALLER: Do not reuse con- below the mean high water mark.Do not apply when weather conditions favor , Mix one(1)part BIOMISTc 12+60 with two(2)parts solvent and apply at the CtaON Wrap containers in several layers M newspaper and discard in drift from treated areas.Drift and runoff treated areas may be hazardous to following rates. of aquatic organisms in neighboring areas. Do not contaminate water when vIA 'F URED BY trash. Permethrin/PBO Application Rates Fl.oz.finished spray disposing of equipment washwaters. LARKE MOSQUITO CONTROL CONTAINERS LARGER THAN ONE GALLON:Metal Containers- pounds/acre Fl.oz./Min. per acre 5MPH 10MPH 15MPH Triple rinse or equivalent.Then offer for recycling or reconditioning, or PHYSICAL OR CHEMICAL HAZARDS PRODUCTS INC. 0.007/0.035 9.0 18.0 27.0 3.0 puncture and dispose of in a sanitary landfill, or by other procedures Do not use or stare near heat or open flame.Flashpoint minimum of 300 F ' 0.0035/0.0175 4.5 9.0 13.5 1.5 approved by state and local authorities.Plastic Containers-Triple rinse or 159 N.GARDEN AVENUE 0.00175/0.00875 2.25 4.5 6.75 0.75 equivalent. Then offer for recycling or reconditioning, or puncture and sanitary of in a dispose I y DIRECTIONS FOR USE ROSELLE, ILLINOIS 60172 dis p y landfill,or b incineration,or if allowed by state It is a violation of Federal Law to use this product in a manner FOR A 1:3 BIOMIST^12+60 ULV/SOLVENT DILUTION RATIO and local authorities, by burning. If burned, stay out of smoke. Then inconsistent with its'labeling. Mix one(1)part BIOMIST^12+60 with three(3)parts solvent and apply at the dispose of in a sanitary landfill or by other approved state and local E.P.A. EST. No.8329IL01 following rates. procedures. CONDITIONS and RATES to USE EPA Reg. No.8329-41 Permethrin/PBO Application Rates Fl.oz.finished spray pounds/acre Fl.oz./Min. per acre IN CASE OF EMERGENCY,CALL INFO TRAC 1-800-535-5053 for MOSQUITO CONTROL 5MPH 107 PH 15MPH 0.007/0.035 12.0 24.0 36.0 4.0 Permethrin/PBO Application Rates Fl.oz.Blomisrn'12+60 0.0035/0.0175 6.0 12.0 18.0 2.0 pounds/acre Fl.oz./Min. per acre NET CONTENTS 5MPH 1OMPH /5MPH 0.00175/0.00875 3.0 6.0 9.0 1.0 0.021/0.105 9.0 18.0 27.0 3.0 FOR A 1:7 BIOMISTO 12+60 ULV/SOLVENT DILUTION RATIO 0,0105/0.0525 4.5 9.0 13.5 1.5 NOTICE:Seller makes no warranty,expressed or implied concern- Mix one(1)part BIOMIST",12+60 with seven(7)parts solvent and apply at the • 0.0035/0.0175 1.5 3.0 4.5 0.5 ing the use of this product other than indicated on the label.Buyer following rates. assumes all risk of use and/or handling of this material when use Permethrin/PBO Application Rates Fl.oz.finished spray , and/or handling is contrary to label instructions. pounds/acre Fl.oz./Min. per acre • 5MPH tOMPH 12/95 0.0035/0.0175 12.0 24.0 4.0 0.00175/0.00875 6.0 12.0 2.0 0.0013/0.00656 4.5 9.0 1.5 Air1S. Mosquito control begins By Tom Haworth wait for ears to hatch waitin for q Adams Co. Y g get of mosquito.A premium Mosquito District the right conditions. The district grade ofMalathion will be used to This has been a very wet spring. uses a bacteria(Vectobac)that is control the adults in many areas of Water is good for the fall grain, very selective and kills only mos- the county. We are also going to makes the ground moist for spring quito larva. use some Pyrethrin G and planting, but even the slightest Table salt is seven times more Resmethrins. They are very safe amount of standing water also toxic than Vectobac.It is made out products and have less of an odor. helps make and of sugars and food additives.This Our larviciding will begin im- create more mos- product,either liquid or granular, mediately,with adulticiding done quitoes.Even a 1/ is put into the water and the mos- only as needed. These products 8 of an inch in quitoes have to eat it to die.It lasts will be applied by licensed applica- depth is plenty. in the water approximately 36 tors and according to federal and The life cycle of a - hours. That is why we have to state requirements. mosquito requires �' continue to treat every five to six Anyone with questions or con- water in order to =" " days all season long. cerns should contact the office and develop from an Altosid is put into the storm leave a message at(509)488-2661 egg to an adult.A drains to stop mosquitoes from or write to Adams County Mos- single hoof print ` hatching.It is even less toxic than quito Control District, P.O. Box from a cow or the bacteria. A larvide and 262,Othello,WA99344.Our trucks horse can hold up TOM pupacide oil,Golden Bear 1111,i s are white and our crews are in blue to 1,000 mosquito HAWORTH used to kill the pupa before emerg- uniforms, so everyone will know larva. ing as an adult.Spraying for adult who we are, especially new land Because of the excess amount of mosquitoes is our last chance to owners. water this year, we would like to ask the residents ofAdams County to check around the house,garage and farm shops and buildings for any kind of containers that would hold water. Pop and soup cans, flower pots,lids from bottles,used tires, empty buckets, even pieces of tarps from haystacks. During your spring cleanup or when walking around the yard,if a person will be observant and see any ofthese kinds of water sources, please take time and dump the water out so mosquitoes will have to hunt harder to find a home. Most of our time checking for mos- quitoes is out in the rural areas, but a person would be surprised what is in their own back yards. When the first warm day ar- rives, it seems the bugs do too. Many of the first insects of the season will look similar to a mos- quito,but are not. The first adult mosquito in the spring is called Anopheles. It overwinters (hiber- nates) as an adult, so when the first warm day arrives, it doesn't take long for this creature to wake up. It can even be hiding in the woodpile,or under the shingles.In order to spray for this early riser, the weather has to cooperate. If it is too cold or windy, spraying is less effective. As the water warms, the larva start to develop in certain areas of the county. The mosquito district has records of the areas that begin to produce first. There isn't any product that will destroy the eggs of the mosquito, and the eggs can t Journal of the American Mosquito Control Association, 12(1):45-51, 1996 Copyright® 1996 by the American Mosquito Control Association,Inc. DEPOSITION OF MALATHION AND PERMETHRIN ON SOD GRASS AFTER SINGLE, ULTRA-LOW VOLUME APPLICATIONS IN A SUBURBAN NEIGHBORHOOD IN MICHIGAN R. G. KNEPPER,' E. D. WALKER S. A. WAGNER,' M. A. KAMRIN'AND M.J. ZABIK' ABSTRACT. Deposition of malathion and permethrin onto grass surfaces, after ultra-low volume (ULV) application, was studied in a suburban neighborhood in Saginaw County, Michigan. Commercial concentrates of malathion (Cythion ULV®) and permethrin (Biomist 4 + 121m) were sprayed using a truck-mounted ULV aerosol generator. Sod-grass blocks (0.18 m2) were placed in the frontyard and backyard of homes in the neighborhood at 4 distances to 91.4 m from the road where applications were made. Grass samples were taken from the sod blocks before application and at 15 min, 12 h, 24 h, and 36 h after application. Samples were extracted with solvent,and extractions were subjected to gas-liquid chromatography for detection of malathion and permethrin. Ranges of detection for malathion were 0.0- 16.E mg/0.18 m2 and for permethrin were 0.0-25.9 mg/0.18 m2.Most detections were from samples taken nearest the road at 15 min after application. Detections declined as a logarithmic function of time after application and as an exponential function of distance from the road. INTRODUCTION tle information on deposition and persistence of these compounds after single applications of Ultra-low volume (ULV) application of high- ground-applied ULV, especially in neighbor- concentrate insecticides from ground equipment hoods where these materials are used, we stud- has become a standard method for control of ied these phenomena for malathion and per- adult mosquitoes (Mount et al. 1968, Lofgren methrin on grass in a typical suburban neigh- 1970, Hobbs 1976). The technology involves borhood in Saginaw County. formulations and equipment that produce an aerosol of droplets in a restricted size range that impinge on flying mosquitoes (Weidhaas et al. MATERIALS AND METHODS 1970, Lofgren et al. 1973). Such applications The study was conducted in a 30 year-old present a low health risk to humans because of housing subdivision in Saginaw County, MI, in low dermal exposure and low mammalian tox- July 1993. The landscape consisted of single icity of the insecticides and are thought to have family dwellings, well-kept lawns, ornamental low deposition onto environmental surfaces shrubbery, mature trees, gardens, fences, and compared with expected, "theoretical" values other features generally found in a suburban set- (Tucker et al. 1987, Moore et al. 1993,Tietze et ting in the midwestern USA (Fig. 1). Blocks of al. 1994). Information on deposition and persis- sod grass (0.3 x 0.6 m), placed in plastic hor- tence is important to address regulatory and ticultural flats, were used as targets for insecti- public concerns about insecticide residues in the cide deposition. The flats were provided with environment and their perceived effects on hu- water during the experiment to prevent the grass man health. from drying. The blocks were placed in 2 sets The Saginaw County Mosquito Abatement of 4 lines each(the backyard and frontyard sets), Commission is a publicly funded mosquito con- parallel and downwind from the course of a trol agency in Michigan. Part of the program nearby street (Fromm Drive; see Fig. 1). The includes ULV application of malathion (formu- lines of sod were placed at distances of 7.6 m lated as Cythion ULVIR) and permethrin (for- (25 ft.), 15.2 m (50 ft.), 30.4 m (100 ft.), and mulated as Biomist 4 + 121R) to reduce popu- 91.4 m (300 ft.) from the edge of the street. lations of adult mosquitoes. Because there is lit- There were sufficient blocks in each set to allow for pre-treatment(time 0)and post-treatment(15 min, 12 h,24 h,and 36 h after application)sam- 'Saginaw County Mosquito Abatement Commis- pling for both insecticides at each distance from sion, 211 Congress Street,Saginaw, MI 48602. the street. Grass was sampled from the sod Department of Entomology, Michigan State Uni- versity,East Lansing, MI 48824. blocks by clipping all grass from the top of the 'Institute for Environmental Toxicology, Michigan sod with shears and placing the material into State University,East Lansing, MI 48824. clean glass jars fitted with aluminum foil seals 'Pesticide Research Center,Michigan State Univer- inside the lids. Jars were then placed on wet ice sity, East Lansing,MI 48824. for transport to the laboratory, where they were 45 46 JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION VOL. 12, NO. I Fromm Drive Wind 000013013D 7.6m 0000000o 00000000 p 5.2mD000D0an o 0oD00000 30.5m 00000000 < a 0 o M3, aT m 3 0 w rn O ,+ o � o rn �. -Z {� m 2 2 O O 3 3 00000000 91.4m o00000oo Fig. 1. Schematic diagram of the neighborhood in Saginaw County,MI,where the experimental applications took place.Truck direction was northerly on Fromm Drive.Positions of lines of sod grass blocks(the sampling stations)are shown as small squares in rows at 7.6, 15.2, 30.5, and 91.4 m to the east of Fromm Drive. stored at —20°C.Between clippings,shears were from slide counts using a BASIC computer pro- rinsed once in acetone and then in water. gram (Sofield and Kent 1984). Droplet sizes Malathion (0,0-dimethyl phosphorodithioate were consistent with requirements as stipulated ester of diethyl mercaptosuccinate) was applied on the insecticide labels. During the experimen- as a 95% commercial formulation (Cythion tal application, insecticide droplets were collect- ULV; American Cyanamid)at a flow rate of 104 ed at downwind distances of 7.6, 15.2, and 30.4 ml/min (3.5 fl. oz./min) and a truck velocity of In from the road, using silicone-coated micro- 16.1 km/h (i.e., 10 mph). A 4%commercial for- scope slides mounted on mechanical slide rota- mulation of permethrin ([3-phenoxyphenylj- tors (John W. Hock Co.) set equidistantly be- methyl[+]cis-trans-3-[2,2-dichloroethenyl]-2,2- tween the duplicate sets of sod blocks and ro- dimethylcyclopropanecarboxylate) with 12% pi- tated at 350 rpm for 15 min post-treatment. peronyl butoxide synergist (Biomist 4 + 12; Weather data (temperature, relative humidity, Clarke Mosquito Control Products) was applied wind speed, and wind direction) were collected at a flow rate of 148 ml/min (5.0 fl. oz./min) at during the experiment using an on-site weather the same truck velocity.Applications were made station (Weather Monitor II; Davis Instruments). in the evening between 2100 and 2200 h. The During the insecticide applications, temperature application equipment consisted of a LECO® was 18°C, relative humidity ranged from 52 to Model 1600 cold aerosol generator mounted on 62%, and wind was easterly and light with a a one-half-ton pickup truck. The insecticides velocity of 1.6 km/h (1 mph). During the 36 h were delivered by a positive displacement pump after application, temperatures ranged from 11 with a Micro-Gen®digital flow control. to 28°C, relative humidity ranged from 32 to For purposes of calibration prior to applica- 79%,and wind velocity ranged from 0 to 10 km/ tion for the experiment,insecticide droplets were h (0-6 mph). There was no rain during the ex- collected from the spray cloud using silicone- periment. coated glass microscope slides and the hand- For chemical analyses, grass samples were wave method (Mount and Pierce 1972). Droplet extracted with equal volumes of hexane and ac- mass median diameters(MMDs)were calculated etone,shaken for 5 min,filtered,and mixed with 4 MARCH 1996 ULV APPLICATION OF MALATHION AND PERMETHRIN 47 5% sodium chloride, and the hexane fraction Detections of permethrin and malathion de- was drawn off for analysis with gas-liquid chro- clined in concentration as a negative, exponen- matography using a 60-m DB-5 column with tial function of distance from the road where the electron capture detection.The limit of detection applications were made(Fig.4). For permethrin, for permethrin analyses was 0.10 ppm with the regression equation describing this decline 91.6% recovery, and the limit of detection for was Y= 334(X)(-1.252)(R2 = 0.97, r = 0.98, P < malathion analyses was 0.05 ppm with 89.5% 0.001), and for malathion, the regression equa- recovery. Curve fitting of insecticide mass (ex- tion was Y = 337X'-'349) (RI = 0.99, r = 0.99, pressed as mg/0.18 m2 area of the sod blocks) P < 0.001), where Y is mass of the compound on time after application was done using least- (mg/0.18 m2)and X is distance(m).These equa- squares regression. tions adequately describe the relationships be- tween detection and distance within the range of RESULTS distances in the experiment but should not be extrapolated beyond these ranges. Droplet collections on the silicone-coated slides mounted on rotators showed that the Bio- DISCUSSION mist 4 + 12 droplets had MMDs of 15.7 µm at 7.6 m, 16.1 µm at 15.2 m and 8.9 µm at 30.4 The tendency of insecticides to deposit onto m, whereas the malathion droplets had MMDs objects and surfaces in the environment is rather of 10.6 µm at 7.6 m, 21.2 µm at 15.2 m, and poorly understood, particularly in patchy envi- 29.6 µm at 30.4 m. The distribution of droplets , ronments such as neighborhoods, where such of different sizes that were collected by the slide applications are likely to be made. Drift and fall- rotators,shown in histograms in Fig.2,indicated out of droplets within the size range of ULV that most droplets were collected at the 7.6-m aerosols are affected by MMD of droplets, wind distance from the road, compared with the two speed, air stability, and other factors (Lofgren greater distances. There were significantly more 1970, Tietze et al. 1994). Moore et al. (1993) droplets collected overall after the Biomist 4 + evaluated deposition of malathion on human tar- 12 application than after the Cythion ULV ap- gets immediately following ULV applications, plication (2 x 3 contingency table analysis of using cotton gauze patches and cotton dust frequency of droplets by insecticide and dis- masks as the collection devices, and deposition tance, likelihood ratio chi-square = 28.0, df = on the ground using filter paper as the collection 2, P< 0.001). Inspection of the histograms sug- device. Similarly, Tietze et al. (1994) examined gests that there were more smaller droplets of depositional characteristics of malathion after Cythion ULV collected at the 7.6-m distance ULV application onto filter paper targets. Both compared with Biomist 4 + 12. studies showed low and uniform deposition of There were no detections of permethrin or malathion as a function of distance from the malathion in sod blocks sampled prior to appli- spray head to 91.4 m, whereas in our study de- cation, i.e., at "time 0" (Table 1). Of the post- position onto ground targets decreased along this treatment samples, there were 20/32 detections distance. This result could be related to more of permethrin and 19/32 detections of malathion. rapid fall-out of larger sized droplets closer to Mass of malathion ranged from 0(undetectable) the spray head (Mount 1970) and to the rela- to 16.6 mg/0.18 m2, and mass of permethrin tively greater number of droplets nearer the ranged from 0 (undetectable) to 25.9 mg/0.18 spray head than farther away as the droplets dis- m2. Detections of both malathion and permethrin persed(Fig. 2). Alternatively,differences in pat- were highest in value in the 15-min post-treat- terns of deposition between our study and that ment samples taken at the 7.6-m distance from of Moore et al. (1993) and Tietze et al. (1994) the road (Table 1). Regression analyses showed could be explained on the basis of the complex- that residues at the 7.6-m sampling distance de- ity of the neighborhood environment where our clined as a logarithmic function of time after ap- study was conducted, compared with the open plication (Fig. 3). For permethrin,the regression field settings of those studies. Periods of air in- equation was Y = 18.1 - 11.5[log,o(X)] (R2 = stability (Armstrong 1979) may alter patterns of .0.98, r = 0.99, P < 0.001), and for malathion, deposition, thus the negative exponential model the regression equation was Y = 11.6 - of deposition as a function of distance that we 7.6[log,JX) (R2 = 0.98, r = 0.99, P < 0.001), present (Fig. 4) may apply only when air tem- where Y is mass of the compound (mg/0.18 m2) perature is stable and wind velocity is low. Tie- and X is time (h) after application. Regression tze et al. (1994) observed an increase in depo- analyses at the greater sampling distances over sition of malathion with distance during a single time were not done because of the low detection episode of air instability. values (see Table 1). Overall, our results showed that deposition of 48 JOURNAL OF THE AMERICAN MOSQUITO CONTROL As SOCIAIION VOI.. 12, No. 1 6 0 BIOMIST 4 + 12 50 40 30 x 20 H a 10 x w 0 a p~�, 6 0 CYTHION ULV O 1x Q 50 w ❑ 7.6 METERS O d 4 0 ■ 15.2 METERS z 30 El 30.5 METERS 20 10 0 of T 1p3nlno� rvwElOoonn, n nm,r" r-, P P to to to to to to to to to to N t� N 1` N 1� .4 1-4 N N M M It d MASS MEDIAN DIAMETER (um) Fig. 2. Number of droplets of different mass median diameters collected by rotating slide collectors at 7.6, 15.2, and 30.5 m from the road where applications of Cythion ULV and Biomist 4 + 12 were made. MARCH 1996 ULV APPLICATION OF MALATHION AND PERMETHRIN 49 Table 1. Detection of permethrin and malathion on grass surfaces after ultra-low volume application of Biomist 4 + 12 or Cythion ULV in a suburban neighborhood in Saginaw County, MI. Values are mass (mg) per 0.18-m2 surface area of the sod blocks that were used as sampling devices. Distance from Time after application application Mass of Mass of (m) (h) Sod block location permethrin malathion 7.6 0 Frontyard 0 0 Backyard 0 0 0.25 Frontyard 25.9 16.6 Backyard 23.7 15.7 12 Frontyard 8.1 4.3 Backyard 6.7 3.1 24 Frontyard 1.5 0.3 Backyard 0.2 0.4 36 Frontyard 0.1 0 Backyard 0 0 15.2 0 Frontyard 0 0 Backyard 0 0 0.25 Frontyard 10.2 4.3 Backyard 12.1 5.1 12 Frontyard 3.3 0.6 Backyard 5.6 0.4 24 Frontyard 0.3 0.3 Backyard 1.6 0.1 36 Frontyard 0 0 Backyard 0 0 30.5 0 Frontyard 0 0 Backyard 0 0 0.25 Frontyard 7.2 1.4 Backyard 3.8 1.6 12 Frontyard 0.1 0.4 Backyard 0.2 0 24 Frontyard 0 0.2 Backyard 0 0 36 Frontyard 0 0 Backyard 0 0 91.4 0 Frontyard 0 0 Backyard 0 0 0.25 Frontyard 1.3 0.3 Backyard 0.9 0.4 12 Frontyard 0.3 0 Backyard 0 0.1 24 Frontyard 0 0 Backyard 0 0 36 Frontyard 0 0 Backyard 0 0 both malathion and permethrin tended to be high to spray mechanics, because these conditions nearest to the road where the truck was driven were similar except for a higher flow rate for the during the applications. However, there was a Biomist 4 + 12 formulation (148 ml/min) com- discrepancy in the deposited mass of the 2 in- pared with Cythion ULV(104 ml/min). It is un- secticides on the grass targets.The observed dif- likely that the difference in deposition was ference in deposition of permethrin (a 4% for- caused by some variation in conditions at the mulation) compared with malathion (a 95% for- time the individual applications were made, be- mulation)cannot be explained by factors related cause there were no obvious meteorological • 50 JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION VOL. 12, NO. 1 Y = 18.1 - 11.5[logio(A)J R2 - 0.98 Y = 334X(-1.252) R2 = 0.97 30 30 PERMETHRIN 2 5 LPFRMETHRIN N 25 20 00 N 20 �— 1 5 � � 15 10 ■ 10 \ IVi 5 Q 5 E-, 0 U 0 W � Y = 11.6 - 7.6[loglc(X)] R2 = 0.99 V ) Z 30 P4 Y = 337X(-1.549 R2 = 0.99 to 3 0 w MALAT1110N Z -- O 25 MALAT1110N w 2s c7 20 O .� 20 15 15 V) 10 10 5 5 0 0 10 20 30 40 0o N ,n r, p N 't iri o Ui �o TIME AFTER APPLICATION M V (HOURS) DISTANCE FROM APPLICATION (METERS) Fig. 3. Detections of mass of permethrin or mal- athion on grass taken from sod targets after ULV ap- g permethrin or mal- plication of Biomist 4 + 12 or Cythion ULV insecti- athion on grass taken from sod targets after ULV ap- cides at the 7.6-m sampling distance only. Pre-treat- plication of Biomist 4 + 12 or Cythion ULV insecti- ment sample results are not shown, but all were neg- cides for 15-min post-treatment samples only. Each ative detections. Each point represents a value from Point represents a value from one sod block (n = 8). one sod block(n = 8). The persistence of deposited insecticides after ULV application is not well known. Both per- variations that could have influenced the ob- methrin and malathion have short half-lives in served deposition patterns. Possibly, the higher the environment(Howard 1991), but persistence flow rate for Biomist 4 + 12 resulted in gener- of any insecticide in the environment is affected ation of a greater number of droplets at the spray by its formulation. We found that mass of per- head. There were a greater number of Biomist 4 methrin and malathion declined as a logarithmic + 12 droplets than Cythion ULV droplets col- function of time in hours, with most detections lected on the slide rotators during the experi- of these compounds occurring at the 15-min and ment (see Fig. 2), thus, based upon this empir- 12-h sampling times after application. lh<J ical observation, one would expect greater de- data indicate that neither compoun�pers* t or position of Biomist 4 + 12 droplets than Cy- veil% a r aces a er plica- thion ULV droplets onto the grass targets as tion. We do not ent here a d is well. based upon toxicity and potential exposure of MARCH 1996 ULV APPLICATION OF MALATHION AND PERMETHRIN 51 humans to permethrin or malathion residues on and exposure data for organic chemicals, Volume grass surfaces, but some contact with insecti- III,Pesticides. Lewis Publishers,Chelsea, Mi. cides could occur in barefooted people walking Lofgren,C.S. 1970. Ultralow volume applications of on grass near a road where an application truck concentrated insecticides in medical and veterinary passed, shortly after the time of application. entomology. Annu. Rev. Entomol. 15:321-342. Lofgren, C. S., D. W. Anthony and G. A. Mount. Walkers are unlikely to receive a toxic dose of 1973. Size of aerosol droplets impinging on mos- either permethrin or malathion after such contact quitoes as determined with a scanning electron mi- because of the low mammalian toxicity of these croscope. J. Econ. Entomol. 66:1085-1088. compounds and the miniscule amount of chem- Moore, J. C., J. C. Dukes, J. R. Clark, J. Malone, C. ical on the grass. Moore et al. (1993) concluded F.Hallmon and P.G.Hester. 1993. Downwind drift that direct exposures of malathion after ULV ap- and deposition of malathion on human targets from plication were negligible when presented in ground ultra-low volume mosquito sprays. J. Am. Mosq. Control Assoc. terms of the maximum allowable daily (dermal) ti Mount, G. A. 1970. Optimumum droplet size for adult exposure. mosquito control with space sprays or aerosols of insecticides. Mosq. News 30:70-75. ACKNOWLEDGMENTS Mount,G.A.and N.W.Pierce. 1972. Droplet size of ultra-low volume ground aerosols as determined by We thank William Jany of American Cyan- three collection methods. Mosq. News 32:586-589. Mount, G. A., C. S. Lofgren, N. W. Pierce and C. N. amid for providing the weather station and slide Hussman. 1968. Ultra-low volume nonthei•mal aer- rotators; Matthew Siler and Chris Vandervoort osols of malathion and naled for adult mosquito of the Pesticide Research Center,Michigan State control. Mosq. News 28:99-103. University, for carrying out the chemical anal- Sofield, R. K. and R. Kent. 1984. A BASIC program yses• the staff of the Saginaw County Mosquito for the analysis of ULV insecticide droplets. Mosq. Abatement Commission for their assistance in News 44:73-75. the implementation of this study; and the anon- Tietze, N. S., P. G. Hester and K. R. Shaffer. 1994. ymous reviewers and editor for improving the Mass recovery of malathion in simulated open field mosquito adulticide tests. Arch. Environ. Contam. manuscript. Toxicol. 26:473-477. 1Lcker,J.W.,Jr.,C.Q.Thompson,T.C.Wang and R. REFERENCES CITED A. Lenahan. 1987. Toxicity of organophosphorus insecticides to estuarine copepods and young fish Armstrong,J.A. 1979. Effect of meteorological con- after field applications. J. Fla. Anti-Mosq. Control ditions on the deposit pattern of insecticides.Mosq. Assoc. 58:1-6. News 39:10-13. Weidhaas D. E., M. C. Bowman, G. A. Mount, C. S. Hobbs,J. H. 1976. A trial of ultra-low volume pyre- Lofgren and H.R.Ford. 1970. Relationship of min- thrin spraying as a malaria control measure in El imum lethal dose to the optimum size of droplets of Salvador. Mosq. News 36:132-137. insecticides for mosquito control. Mosq. News 30: Howard,P.H. 1991. Handbook of environmental fate 195-200. ° 32 UsA32- pki 29 �....... . �,� �� v ," vi Sullivan b� ikbig 8bRPORATION 1259 El Camino Real #134 MENLO PARK, CA 94025 Mr . Scott Woodbury 200 Mills Avenue South, 4th Floor Renton WA 98055 5cot� T� f Under Surveillance rence of species known or suspected to be present within an area. Seven Ways to a Successful wdslowlhen candcang rfullymosquito lroach proceed slowly and carefully.Approach the area with caution, not to avoid Dipping Career snakes, although that's a good idea too, Claudia O'Malley but to avoid disturbing larvae at the water's surface. Vibrations from heavy footsteps, casting a shadow or moving vegetation that contacts the water may INTRODUCTION Routine larval surveillance data can be enough to cause larvae to dive to the be useful in interpreting adult mosquito bottom.Try to approach the water while As recently as 1922,members of the surveillance data.For example,if larval facing the sun and with quiet,slow,soft New Jersey mosquito control community surveys indicate 95-100%control by lar- steps, gently move vegetation only as were debating the relative merits of"night vicides and yet the number of adults necessary. collections"as opposed to larval collec- does not decline,one can suspect,in the Mosquito larvae of most genera,par- tion and identification.Some of the past absence of reinfestation, that an impor- ticularly the common Culex,Aedes and practices of mosquito control included tant larval concentration was missed. A Anopheles, are usually found at the treating any standing water encountered, system for the detection of insecticide water's surface and frequently next to regardless of whether or not mosquito resistance is also provided through a lar vegetation or surface debris. In larger larvae were present.Guidelines for start- val surveillance program. pools and ponds, they are usually near ing a mosquito control program included the margins,not in open,deep water.Dip- the advice that directors should not SAMPLING LARVAL MOSQUITOES ping should be concentrated around spend an excessive amount of time on floating debris and aquatic and emergent surveys. Even now, a few still feel that Because mosquito larvae are found vegetation.If there is a strong wind,dip- larval surveys are only necessary in the in a wide variety of habitats,a number of ping should be done on the windward early part of the breeding season;once it different sampling techniques to deter- side of the habitat where larvae and pu- is known what species are present at a mine their presence and density have pae will be most heavily concentrated. site, it can be taken for granted that the been developed. Many,if not all,of the Look for larvae and pupae before begin- species composition at that site will re- published methods are described in Mike ning to dip,if possible.If it is raining on main the same throughout the rest of the Service's book,Mosquito Ecology Field the water's surface,get back in the truck, season. Most experts,however,feel that Sampling Methods (Elsevier Applied go have a cup of coffee and wait until the larval surveillance is not only an impor- Science, 1993).. Some methods are com- rain stops. tant aspect of an effective mosquito sur- plex mechanical devices, but the most Each water body may contain a num- veillance and control program, but it is commonly used larval collection method ber of different microhabitats which an essential component. is the "standard dipper," that plastic or could contain different mosquito species. metal,white or aluminum,solid or screen- Microhabitats are such places as under BENEFITS OF LARVAL bottomed pint to quart-sized scoop-on- tree roots, within clumps of emergent SURVEILLANCE a-handle, that, along with the "sweep vegetation, under floating or overhang- net,"defines the Ultimate Inspector.Let's ing vegetation and in open water.Learn Larval surveys have many important take a closer look at dipping. to recognize different microhabitats functions. They are used to determine Dipping for mosquito larvae may,at within an area and sample as many as the locations and seasons that mosqui- first,seem like a very simple thing to do. possible in order to obtain an accurate toes use specific aquatic habitats and, After all,who hasn't dipped water from a picture of the area's species composition. when specimens are identified and bucket or stream to quench a thirst or counted,the information can be used to cool the top of one's head? Well, think A CHOICE OF SEVEN determine species composition and popu- again. Dipping for mosquito larvae is not lation densities. The information can be dipping to take a drink. The technique Now that you've found your way used to determine optimal times for ap- starts long before the dipper is put into safely to the edge of a marsh, pond, plication of larval control measures,in- the water. It begins hours or days before ditch,swamp or woodland pool,what do cluding chemicals,biologicals,draining the actual dipping and at least 10 feet you do with your dipper. Just plunge it or impounding. It can also be used to away from the water's edge. in? That's fine if you need water,but not help forecast the need for adult mosquito The species of mosquitoes one is necessarily if you want to catch mosqui- control and to help assess the effective- looking for and the type of habitat being toes. Believe it or not, there are seven ness of both chemical and biological con- sampled will,in part,determine the sam- basic ways to dip for mosquito larvae. trot measures. pling method used. Thus,it is important Which one or ones you use depend, as that field personnel know the preferred we mentioned earlier, on the genus or breeding habitats and seasonal occur- genera of mosquitoes you suspect may WINTER 1995,WING BEATS 23 be present and on the habitat,microhabi- ten the method referred to in much of the tat and weather conditions. literature as "the standard dipping pro- The first and usually the best method cedure." While it can be successfully to start with is the SHALLOW SKIM.The used to collect Culex larvae,it is still not shallow skim consists of submerging the the method of choice. leading edge of the dipper,tipped about 45 degrees,about an inch below the sur- face of the water and quickly,but gently, �{ t moving the dipper along a straight line in open water or in water with small floating In very shallow water,try the FLOW- debris.End the stroke just before the dip- IN method. Larvae can be collected by per is filled to prevent overflowing.The pushing the dipper into the substrate of shallow skim is particularly effective for the pool and letting the shallow surface Anopheles larvae that tend to remain at water,debris and larvae flow into the dip- iA the surface longer thanAedes and Culex. per. Do not move the dipper horizon- Anopheles are usually associated with tally. The dipper can also be used as floating vegetation and debris. BACKGROUND. This is especially use- ful in woodland pools and other shallow water or when larvae are disturbed and ' dive to the bottom. Submerge the dipper completely to the bottom litter and slowly move it around.The darker mosquito lar- vae and pupae will stand out against the `r- �f � background of a white or aluminum dip- per.Once larvae appear in the dipper,just r f ? lift it upward. To sample for larvae that may be un- The second method to try in open der floating or emergent vegetation,use water,with or without floating objects,is the SCRAPING technique.This method the COMPLETE SUBMERSION. Many is used in habitats that contain clumps mosquito larvae,particularly those of the of vegetation such as tussocks of sedges, genera Aedes and Psorophora, are very floating mats of cattails or water lettuce active and usually dive below the surface or other plants that are too large to get in quickly if disturbed. In this case,a quick the dipper,or clumps of submerged veg- plunge of the dipper below the surface of etation such as hydrilla or bladderwort. the water is required,bringing the dipper Dip from the water in towards the veg- back up through the diving larvae. Bring etation and end by using the dipper to One or more of these methods,prop- the dipper up carefully to avoid losing the scrape up against the base or underside erly used, can determine the mosquito larvae in the overflow current. of the vegetation to dislodge larvae. This species composition of most aquatic method is usually more effective if the habitats, excluding those whose open- bottom of the dipper is screened and it is ings are smaller than the dipper,such as often used to sample for Coquillettidia tires,rock pools, treeholes and tree root and Mansonia mosquitoes. systems like those found in cedar and red maple swamps. In those cases, a smaller container,such as a vial,measur- ing spoon or tea strainer can be used in the same seven ways as the dipper de- scribed above. Then there is the tubular dipper,the chefs poultry baster,for those When you need to sample at the really hard to get to places like plant ax- edges of emergent vegetation, try the ' ,, ils,tree holes and tree root holes. PARTIAL SUBMERSION technique.To ; i � Now that we know how to efficiently do this, push the dipper, tilted at about collect mosquito larvae, what do we do 45 degrees,straight down adjacent to the The SIMPLE SCOOP is the"dipping with the specimens and the data. That's ' vegetation.This causes the water around to get water" method that was discour- the subject of a future article. Until then, the vegetation to flow into the dipper, aged earlier.It consists of simply scoop- happy dipping. carrying the larvae with the flow. There ing a dipperful of water.This is probably Claudia O'Malley is is no need to move the dipper horizon- the most commonly used method, par- l ur ingtbn I+Caunty Mosquito 1 to ri j tally. Pull the dipper up before it is full. ticularly by new inspectors,and it is of- "ae va.+ u mt�s.on.a.n X.... 24 WINTER 1995,WING BEATS 4 � ) /T - J - MARIN / SONOMA MOSQUITO ABATEMENT DISTRICT First Organized District in California 556 No.McDOWELL BLVD.,PETALUMA,CALIFORNIA 94954 / (707)762-2236 May 5, 1995 BOARD OF TRUSTEES PRESIDENT WARREN HOPKINS ROHNERTPARK Debbie Fisher VICE PRESIDENT Rainer Audubon �SANANSELBMMO 26029 1 19th Drive S.E. SECRETARY Kent, WA 98031 TOM MILLER SONOMA COUNTY AT LARGE WINDSOR Dear Debbie: JOHN BERG FAIRFAX CHARLE3 BOUEY I am enclosing copies of various information sheets regarding our mosquito SONOMA abatement program. We have utilized an integrated approach for years. LOU BRUNI Marsh managpement and tidal recirculation ditches have been extremely MARIN COUNTY ATT LARGE b J HENRY FUHS successful in reducing the impact of our two salt marsh mosquitoes,Aedes COTATI sguan iger and Aedes dorsalis. I have included several papers on this aspect THOMASJ GORDON of our program.. Each of the twenty-one species of mosquito that are found NOVATO JOHNGOVI in the two county area are dealt with in a specific fashion. For example, SAN RAFAEL Culex pipiens,the House Mosquito generally breeds in water high in organic JOHN'JACK'HEALY content, i.e. catch basins with leaf and grass clippings, septic tanks etc. Other SANTA ROSA species, e.g.Aedes siet•renses, the Western Treehole mosquito breed in BELVEDERE rothole cavities of trees and is an extensive problem in Marin County. RICHARD RYNO PETALUMA All but the Aedes sier•rensis are controlled in the larval stage, before they ROGER SMITH TIBURON become an adult. With the logistic difficulty of reaching over 10,000 LEONARDSTAFFORD treeholes to control the larvae, we rely on a ULV (Ultra Low Volume) ROSS spraying program. It is limited to individual residents property and very ROCKYTHOMPSON SEBASTOPOL restricted small areas within the two county area. MANAGER CHARLESH.DILL I hope this package of information helps and if the person organizing the ADMINISTRATIVE ASSISTANT JAMESA.WANDERSCHEID control effort could contact us we would be happy to discuss control VECTOR ECOLOGIST strategies with them. RONALD KEITH ADMINISTRATIVE SECRETARY SANDRA J.LA POINTE Sincerely, DATA ANALYST VICKI McCULLOCH � J SUPERVISORS ' TOM COOPER CHUCK KRAUSE Ronald Keith Vector Ecologist Guidelines for the Ecological Control of Mosquitoes 1 r# rR ININO,. f Y in on-tridal Wetlands of the San Francisco Bay Area Joshua N. Collins � M and r� Vincent H. Resh 1989 MARIN/SONOMA MOSQUITO ABATEMENT DISTRICT 556 NORTH McDOWELL BOULEVARD PETALUMA, CALIFORNIA 1- ( 800) 231-3236 ( 707) 762-2236 The Counties of Marin and Sonoma provides a program for the control of mosquito pests and disease vectors. Vectors are mosquitoes capable of transmitting disease or causing injury to human beings . These services are available to residents within the district boundaries . SERVICES INCLUDE: -Community educational programs Speakers available for Schools , Civic or Business Groups and Homeowners Associations -Property inspection for vector problems -Information and advice on control of vectors -Mosquitofish planted in residential ponds (no charge) -Mosquito surveillance and control activities -Insect/animal/tick identification -Surveillance for malaria, encephalitis and other vector borne diseases -Information and referral services -Also see Community Resource Numbers listed on back of this page Cost No Charge - services supported through District funding Hours Monday through Friday 7 : 00 am to 3 : 30 pm Funding is provided by a small service charge that is assessed annually on all non-exempt land parcels. The District is administered by the Board of Trustees comprised of one member from each represented city and one member from each of the counties . COMMUNITY RESOURCE NUMBERS ANIMAL REGULATION (stray animals, rabies control & licenses) Sonoma County-incorporated see Govt. pages "City of" unincorporated 707-527-2471 Dog License Info. 707-527-2833 Humane Society 707-542-0882 Marin County Dog Licenses 415-499-6133 Animal Bites/Rabies 415-499-6873 Marin Humane Society 415-883-4621 AGRICULTURAL COMMISIONER (pesticide complaints & ques- tions, pest detection, insect identification) Sonoma County 707-527-2371 Home & Garden Calls 707-527-2621 Marin County 415-499-6349 CALIFORNIA COOPERATIVE EXTENSION (info on ter- mites, gophers of other insects & pests ) Sonoma County 707-527-2621 M-F 900am-100pm Teletip (recorded messages on home & garden publications) 707-575-8341 Marin County 415-499-6352 ENVIRONMENTAL HEALTH SERVICES Sonoma County 707-576-4765 Marin County 415-499-6907 BEE KEEPERS Sonoma County- Brian Flannery 707-996-4755 Jim Hall 707-539-9381 Louie Andrade 707-571-1921 Marin County- Frosti Allen 415-332-3506 John Straka 415-381-1249 Mr. Salvisberg 415-472-1856 POISON CONTROL CENTER 800-523-2222 415-476-6600 AIARIN / SONOI`U MOSQUITO ABATEMENT DISTRICT First organized District in California 556 No.McDOWELL BLVD.,PETALU.NLk CALIFORNIA 94954 (707) 762-2236 Insects Which Resemble Mosquitoes N'on-biting insects that closely resemble mosquitoes are found in both Marin and Sonoma counties at various times and places throughout the year. The insects listed on the front and shown on the back of this page all belong to the order Diptera (flies). (Included in this order are mosquitoes.) These non-mosquito insects are frequently the cause of phone calls to our office. The following information may help indMduals recognize other insects which might otherwise be considered mosquitoes: Zidges ( family - Chironomidae) are the most widespread and numerous ins,.cts resembling mosquitoes. When abundant they may be seen swarming in the air or resting in large numbers on walls, screens, shrubbery or buildings, particularly during the warmer part of the day. 'Midges develop as larvae in water such as lakes, streams, ponds, or pools. They most often cause concern when they emerge from large aquatic habitats that are adjacent to residential areas. However, since the midges are usually short-lived in the adult stage and will ordinarily disappear within a short period of time, many residents find adequate compensation for the temporary inconvenience of the midges in the interesting variety of wildlife (usually birds) associated with the aquatic sources of midges. Residents may use measures listed at the bottom of this page to reduce the number of midges inside the home. Winter Crane Flies (family - Melusinidae) are often quite abundant in '.N4arin and Sonoma counties during the winter. They so closely resemble mosquitoes that they are frequently mistaken and reported. They develop in decaying vegetation - a favorite place being a pile of leaves. They are of no health or pest significance. Crane Flies (family - Tipulidae) are delicate insects var37ing in size from 1/16 of an inch to as large as 1 1/2 inches. The largest crane flies are sometimes called "daddy-long-legs", "Texas mosquitoes" or "'Mosquito HaH-ks" (they do not eat mosquitoes). Although some crane flies resemble mosquitoes, they are harmless. Some species of crane flies emerge from aquatic sources and others from moist terrestrial environments. Fungus Gnats (family - Alycetophilidae) are common in the fall, spring and early summer. Larvae feed on fungus and prefer leaf litter, decaying vegetation, etc. Adults can be very abundant at times. The following measures can be used by residents to reduce the numbers of insects entering the home: 1. Keep doors and windows tightly screened. 2. Turn off porch lights if they seem to attract great numbers of insects. Some Insects from the Order Diptera biting beak (proboscis) Mosquito Family: Culicidae /.G�,, .,•�1r.•, -tom� --,..:•:. \_ i ' no beaker Gall Midge Midge Clear Lake Gnat Family: Cecidcmyiidae Family: Chironomidae Family: Chaoboridae � lJ' 1r� .A, _ Fungus Gnat Dixa Midge Family: Mycetophilidae �� Family: Dixidae Crane 1--Iv Family: Tipulidae l;at]u'oom Fly Black Gnat Dance Fly Family: Psychodidae Family: Ceratopogonidae Family: Empididae Using Fish to Control Mosquitoes Proper pond design is important to minimize mosquito breeding habitat and enhance mosquito fish production. osquito fish (Gambusia al5inis) are used extensively by mosquito aba, ^,lent agencies throughout the world to help control mosquito larvae. The adaptability and hardiness of mosquito fish, coupled With their ability to produce large numbers of young in a short period of time, has mace them of inestimable value as a biological control agent. '�j.e fe—males range from two to two and a half inches in length and the males usually r,,Easure from one to one and a half inches long. Under optimum condi- tions fe-:ale fish can reach sexual maturity in six to eight weeks. The females may bear three to four broods of young in a season, the first of Which may num- ber only a dozen eery tiny young. Thereafter a female may produce from 60 to 100 yo,.:-:g per brood. Under favorable conditions mosqu3t.o fish »•ill live two to three years in this area. Feeding Mosquito fish seldom need supplementary food. During the summer there is usually enough food in the pond for them, and in the winter their bodies slow down so ;,such that eery little food is required. If they are given supplementary food, caution must be exercised. An overfed fish will not take care of the mos- quito problem, and any excess food that the fish do not eat can cause a bacterial bloom u-hich can be toxic to the fish. Pond Design & Although mosquito fish like the shelter of some rocks and plants, they do not thrive well in heavily shaded ponds, and they will tend to dwell in the sunny Maintenance portions of the pond. In large ponds the fish may even avoid mosquito infested shaded areas if the fish are finding or are being fed other food. Because mosqu3t.o fish are cannibalistic, plants are a necessary shelter for the very tiny young. Proper pond design is important to minimize mosquito breeding habitat and enhance mosquito fish production. Manuals on pond design are available from California Department of Fish and Game as well as commercially available. The pond should be designed so that run-ollf waters do not enter the pond. This rill prevent contamination of the pond by silt:, fertilizers and pesticides. The pond should be at least six inches deep and should be cleaned periodically to remove leaves and debris. Plastic wading polls seldom make suitable fish ponds because they are shallow and thus cause the wafer to get excessively warm. High tem- peratures may deplete the oxygen supply causing excessive bacterial develop- ment and may also enhance algal growth. Normally six to ten fish are stocked in MARIN / SONOMA MOSQUITO ABATEMENT DISTRICT 556 No.McDowell Blvd 0 Petaluma, CA 94954 - (70i) 762-2236 an average home pond. If a large number of larvae are present, more fish may be introduced. In some cases, the pond may need to be drained and cleaned or may need to be treated with safe, state approved chemicals prior to the introduction of fish. Limited amounts of algae in artificial ponds may, at times, be beneficial to mosquito fish, but too often it is indicative of other problems. Corrections of the conditions which lead to varies algae problems is not always simple and repeated draining, cleaning and changing of the water may be necessary. Due to the toxic properties of some algicides on fish, these chemicals should be used only on advice of a knowledgeable person. Suitable materials and instructions may be obtained from local tropical fish shops or possibly from garden supply centers. Transportation Fish transportation must be done correctly to avoid weakening or possibly killing the fish. ?fetal containers are not recommended because of their ability to heat rapidly and thus W2TM the water excessively. Also, some materials are highly toxic to fish. Plastic buckets or plastic bags work quite well for transporting fish short distances. A large surface air supply is essential so be careful not to fill containers too full of water, and do not use sealed containers without providing adequate air space. Keep plastic con- tainers out of the sun during transportation and introduce fish into the pond as soon as possible. When introducing fish into the pond, it is recommended that you add pond water to the con- tainer or place the container in the . pond to allow the water temperature of the container to equalize with the pond temperature so as not to shock fem,•ale the fish. male About the Di Objective: To provide an effective District abatement program primarily di- rected toward the prevention, elimi- nation or control of aquatic sources leading to production of mosquitoes capable of disease transmission, or serving as a public nuisance. Approach: under California Health and Safety Code, mosquito abatement districts are granted powers to take all necessary and proper steps for elimi- nation and extermination of mosquitoes. To implement the program objec- tives, district personnel make routine inspections of countless mosquito sources, such as ditches, channels, lagoons, drain lines, marsh areas, creeks, lakes, flood control basins, utility vaults, catch basins and fish ponds. When mosquito production is found, appropriate action is taken to control or elimi- nate the problem. Much of this activity is not readily observable to the general public, except for persons directly involved with specific problems. Your Responsibility: Chapter five of the California Health and Safety Code provides that any mosquito production site declared to be a nuisance must be abated by the property owner. If you have a pond and would like fish or an inspection, please call the District Office at (800) 231-3236. MARIN / SONOMA MOSQUITO ABATEMENT DISTRICT 556 No.Mcl o%vcll Blvd - Petaluma,CA 94954 - (707) 762-2236 MARIN / SONOMA MOSQUITO ABATEMENT DISTRICT First Organized District in California 556 No.McDOWELL BLVD.,PETALUMA,CALIFORNIA 94954 (707)762 2236 September 1 , 1993 Attention Resident: BOARD OF TRUSTEES PRESIDENT In the past few weeks many residents in your area RICHARDRYNO have experienced mosquito problems. A technician with PETALUMA the Marin/Sonoma Mosquito Abatement District has set VICE PRESIDENT light traps, and the results make it clear that large JOHNGOVI numbers of mosquitoes are coining from a water source SECRETARY nearby. TOM MILLER SONOMA COUNTY AT LARGE Of the three most common species found, two are CHARLESBOUEY involved in the transmission of the encephalitis virus SONOMA in nature. One transmits the virus from bird to bird LOU BRUNINI (natural host) and the other from birds to man. The MARIN COUNTY ATLARGE third is a vicious, in-door biter. LYNNHAMILTON All the known sources of standingwater in the SEBASTOPOL WARREN•HOPKINS vicinity have been checked. The technician feels that ROHNERTPARK the probable source is standing water either under a GREGORY JONES,JR. house or in a container, pond or pool in a backyard. SANTAROSA There is a high water table in your area. Any water JOANJACOBSON collecting under a house is slow to drain. It is also SANANSELMO felt that some of the houses in the area may have HENRYFUHS plumbing problems, resulting in an accumulation of COTATI leaking water. FLORA PRASZKER MILL VALLEY q The Marin/Sonoma Mosquito Abatement District is a EVAN•PUGH public, tax-supported agency. . .no fees are charged. The BELVEDERE district relies on the voluntary assistance of residents DONALDBATTEN in tracking down mosquito larva sources . TIBURON If residents do discover a standing water source, LEONARDSTAFFORD the district technician will treat It at no cost. ROSS Please call the toll-free number, 1-800-231-3236 , either NORMANRICHARDSON to let us know of a possible source, or to report an CORTEMADERA outbreak of mosquitoes around your home. CHAR ES HE DILL The District' s first priority is to locate the source and eliminate it. If that is not possible the SUPERINTENDENT/OPERATIONS JAMES A.WANDERSCHEID source is treated with a safe biological compound that Spec C m�c.�u VECTOR ECOLOGIST 1 i RONALDKEITH sprays to kill adult mosquitoes as a last resort, le. ADMINISTRATIVE SECRETARY either when adult mosquitoes or requests for service SANDRA J.LA POINTE reach an unusually high number. No one is penalized for DATA ENTRY/SECRETARY having leaky pipes or other mosquito sources on their VICKIMcCULLOCH property. Our prime concern is the health and safety of the residents. By working with homeowners, the district has established a record of success in finding and controlling residential mosquito problems . We greatly appreciate your help. UNDIP-74R YOUR WATER HOME 222222222222 Dear Resident: It has come to our attention that several homes in your neighborhood have water underneath them. This could be a result of plumbing problems or other sources. This situation, IIII if not corrected can create tremendous mosquito problems as well as subsequent problems with dry rot in the subflooring of your home. We would like to ask for you cooperation and help in locating water accumulation under homes in your neighborhood. Would you please take the time to examine the crawl space or view through the outside vents to see if your home has this problem. If you find water under your house please call us at 1-800-231-3236. We can then h address the issue and if the water is there due to a plumbing g problem, you have every right to have it corrected by the developer at no cost to you. The Marin/Sonoma Mosquito Abatement District is a county Special District. We operate on property tax revenue and any service we provide to you is covered by your property tax. u Thank you for taking the time to help us prevent problems in the future. �1k :..v.,.. FACTS ABOUT THE NARIN/SONOMA M7SQUITO ABATEMENT DISTRICT The District was organized November 6, 1915, the first in California. It operates under Sections 2200-2426 of the California Health and Safety Code. The Marin/Sonoma Msquito Abatement District now covers approximately 960 square miles and is governed by a Board of nineteen trustees. It services approximately 500,000 people. The Cities appoint seventeen of the trustees, the Board of Supervisors of each County (Marin & Sonoma) appoint one to represent the unincorporated protions of the District.. There has been one case of mosquito borne encephalitis in Marin County, (Novato, 1968) . In Sonoma County there were two human and, at least, 13 horse cases of mosquito borne encephalitis since 1957. There are nineteen species of mosquitoes found in the District. Salt marsh mosquitoes, tree hole mosquitoes and house mosquitoes are the most bothersome. Salt marsh mosquitoes can fly up to twenty miles and breed at rates of up to five million per acre under favorable conditions. The others, though localized, are regularly found in residential areas. bbsquito source reduction is emphasized as the primary method of control. When this method and/or biological control (mosquito eating fish) cannot be used, pesticides are applied by power equipment and hand sprayers. The District no longer uses aircraft for spraying. Pesticides are used at rates and under conditions which caTply with specifications of the State Department of Health and State Department of Agriculture. The District consists of 18 permanent employees. A Manager, Vector Ecologist, Superintendent/Operations, Administrative Secretary, Data Entry/Secretary, 2 Supervisor Specialists, Shop Supervisor, and 10 Vector Control Technicians. The District also has 6 Seasonal Mosquito Control Technicians. The office staff receives and records aDproximately 3,000 requests a vear. 11 /90 MOSQUITO BIOLOGY Culex eiythrothorax Introduction Morphology Culex erythrothorax is a medium-sized mosquito that Egg:_White when first laid, darkening to a light brown was first described by Dyar in 1907. It is commonly within a few hours. Individual eggs are elongate with called the tule,mosquito. one end bluntly rounded and the other pointed. They are 1.0 mm long. Eggs are laid together on end Classification, forming a boat shaped raft that floats on the water Phylum Arthropoda (crustaceans,spiders,insects) surface. Class Insecta insects) Order Diptera(flies) Family Culicidae (mosquitoes) Subfamily Culicinae C:_ Genera Culex Subgenera Culex •� :`fi Species eryrhrofhorax Distribution Larva: Larvae have three body parts: head, thorax, In North America, Cx. erythrothorGx populations have and abdomen. A spiracular apparatus or siphon is been collected from eight states: Arizona, California, located on the terminal abdominal segment. Larval Colorado, Idaho, Nevada, New Mexico, Texas, and instars range in size from 1.5 mm for a first stage to 5.0 Utah. In California, it has been collected from eastern mm for a fourth stage. Color varies-from clear to green Sierra, northern coastal, northern central valley, and with external sclerotized areas a light brown. A key cascade counties. larval characteristics are: (1) a siphon tube more than six times as long as basal width; and, (2) the 3rd and 4th siphon hair tufts out of alignment. �`•;;�7 � 1 1 1 _ a Adult: Key adult characteristics are (1) proboscis Life Cycle without a white band; (2) reddish-brown thorax; and (3) narrow white bands on top of abdomen. As illustrated, Cx. erythrothorax has four distinct life stages: egg, larva, pupa, and adult. Depending on environmental conditions, the life cycle can be completed in 12 to 19 days. ADULT days to weeks I} Jr EGGS Z PUPA - ! 11 1 to 2 days - 2to3days LARVA ISt tI LARVA <th 1 1/2 to 2 days -. d to 7 days. - LARVA 3rd '.ea�v� M ,_ LARVA 2nd 1 i ;•�- t_ - 2 to 3 days -- Y.= 1 7/2 to 2 days y - ° Ecology Adult Cx. erythrothorax have four distinct daily activity periods based on light intensity: swarming, sugar or In northern California, overwintering females leave host feeding, finding refugia, and resting. winter resting in the spring and begin deposhing eggs In aquatic habitats. Ensuing generations of females continue to produce and deposit eggs through the summer until fall. Egg laying ceases in the fall when females enter winter resting sites and does not resume until the following spring. Immature stages larvae and pupae) appear in early spring and are present in anaquatic habitats until late fail. D1�1 °AWN q m�.,r<.rme t.a t>no..;.. Seasonal Cycle-Northern California Wonth: Jan Feb War'-Apr M.ay Jun Jul Aug Sep Oct Nov Dee DAY Sage: E E E E E E E E E reet'ap L L L L L L L L L L P P P P P P P P P AF AF AF AF AF AF AT AP AF A.F AM AM AM AM AM AM AI.1 AM AM Gk erythrothorax females feed primarily on mammals. E-egg L-larva P-pu;.a AF-aduhfenale AY-adullna)e Cattle and horse represent 75% of the blood meal. &old-peakpcpu!aliors Birds account for only 2% of the blood feeding. Mating occurs in male swarms that form at dusk, Cicken swarms containing a few to hundreds of males z.4z orientate over prominent objects (trees, bushes). Single females fly into the swarm and are pursued by males. After joining terminalia (sexual organs) the pair lands, and assumes an end to end posture. In 15 to 30 Cattle9x seconds copulation is completed, the pair separates, and they fly away. Cx. eryhrothorax females have .an oviposition preference for aquatic habitats with a rich growth of Passerine tules or cattails. - 7Z Larval Habitats Acrlcufture Indust, Domestic Natural wet:ancs - na.5he5 When populations are high, adults readily disperse In spring and summer months, flight range is limited to from breeding habitats and can become very within a mile and a half of the breeding habitat. During pestiferous in rural and urban areas. Females will feed the fail migrating females can fly a few miles. on human hosts outdoors during dusk or night hours. Diseases vectored -- Virus Protozoan Round Worms Flight range from breeding habltat (miles) Western Equine Encephalitis None None 0.00 0.110 1..00 1..50 2.,00 St.Louis Encephalitis Turlock California Encephalitis Kele (daily) unknown Control Measures Kale (maxinur.,) unknown' Immature mosquito populations can be reduced by a combination of physical and chemical methods. Biological control agents are mosquitofish and Fenale (daily) unknown naturally occurring beneficials such as backswimmers, beetles, and flatworms. Mosquito Abatement Districts currently apply a bacterial protein crystal (Bn), an Fersie (�zXt�um) =000 75 insect growth regulator'° (methoprene), and a light mineral oil (GB 1111) to mosquito breeding sites. Adult populations.,. can - be reduced . with specialized equipment that dispenses aerosol droplets of a plant extract (pyrethrum) ?: ' Ken Boyce&Susan Maggy,Sacramento/Yolo Mosquito&Vector Control District '; California Mosquito Control Association hios ITO NOTES A FOUL WATFIR MOSQUITO LIFE CYCLE Mosquitoes have four distinct life stages as seen in the illustration, with the first three stages of Culex (egg-larva-pupa) being spent in the water. An adult female lays about 150-200 eggs in clusters t called rafts, which float on the surface of the water until they hatch in about one to two days. Females usually prefer to lay eggs in standing, polluted water, such as sewage, street drainage, industrial wastbs, and backyard sources that include swim- ming pools, 6rnamental ponds, cooler drain-water and foul water in containers. A wide variety of other water sources may also be infested with the aquatic stages of this common mosquito. T'he eggs hatch into larvae (wigglers) which then feed on small organic particles and micro,Organisms in the water. Clilex larvae may hang from the water surface by the tip of their tail (siphon) when they feed or they may feed along the bot- tom, but they must return to the water surface to GENERAL INFORMATION breathe. At the end of the larval stage, the mosqui- to molts and becomes the aquatic pupa (tumbler). This species is referred to as a "foul water" mos- The pupa is active only if disturbed, for this is the quito due to its association with polluted water. 'cresting" stage where the larval forni is transfonn- C. peus is a dark bodied, medium-sized mosquito cd into the adult. This takes about two days during with a prominent white band on its proboscis which time feeding does not occur. When the trans- (beak) and white hands on the tarsi (feet). It is formation is completed, the new adult splits the further characterized by black scales which fon» pupal skin and emerges. Under optimum condi- "o" spots on the underside of the blunt-tipped ab- tions development from egg to adult taries about a donten. The adult mosquito most closely resembles week. However, all mosquito developmental times Culex larsulis but lacks the white stripe Qn the hind are dependent on the temperature of the water in legs. Males resemble the females except they have which they mature. bushy antennae and lung palpi on their heads, and These mosquitoes may live for two or three "claspers" on the tip of their abdomen. weeks in the summer, but under cooler conditions This mosquito is found throughout the Western the females may live for several months. In areas of United States from Washington south to Mexico, moderate climate, larvae may be found in every Central America and northern South America. month of the year, but in areas with cold winters EGGS LARVA PUPA ADULT this species usually passes the winter as Inbcnlali„g containers that hold rain or sprinkler water. are females in protected natural or artificial shchers emptied weekly or nrod.ified so they will_not hold such as' cellars, outbuildings, wood piles, cavos, Water. Initiation of' corrective aclion by requiring. culverts, etc: high water qualify standards for ewerage, agricul- tur:,l, or industrial effluents play he the most inl- HABITS (:'ll)tlLT BLIIA1 10H.) porta!lt first step at a community level. Female foul water Irlosquitocs Seim to prefer to li;( 1.00;iCAL CONI ROL: feed upon birds, but ::!, ,i -c;i:.iun will 1ee,l riiva l)f,tcn a source of the foul water mosquito may stock and rarely, rnan. ,`.!ales feed oil nectar and )last lllis:S. 1'Clllales 1:.;, also feed on �!:u;l � l,c.;,, he c.,ntn,IlcJ by stocl.inr musyuit.� fish (�:unrhusiu 1 j y 1 1t affxca) or guppies. Nevertheless, :;<,urces that pro- but usually must have a blood meal in order to develop their eggs. This species is capab!e of mov_ direr. great numbers of the feral waft-r mosquitoes ing 1 - 2 miles seeking a host. but is most comlllOn- are often too polluted to allow fish survival. ly found near its aquatic habitat. CIil ICAL CONTROL: ECONOMIC .AND 111LD cm. lmroitTANCE 1)ue to the often delicate environnlcnt:,l interrc- lationships ol'sonle pon,_Is, chemical k-ontrul should The foul water inosquiloes do occasionally cre- only he practiced by trained mosquito abatement ate dornestie, industrial, and agricultural pest prop- or health department personnel. 'l hese officials lenls due to large nunshcrs front such sources. Al- have knowledge of the proper compounds and ap- though Western Fquiile Encephalitis (WLE1 has plication trLhnigties to assure nlillimal I environ- been isolated from natural poptll.,tions of these mental side effects. Public health agencies generally mosquitoes, their rl•IUCt:,11Ce Io hite elan n-ducts are able to provide information and assistance their efficiency as disuse carriers. where organized mosquito control programs are CONTU.01. METHODS unavailable. It is important to re,nenlher that chemical con- PRI VEJNTION AN17COI1 RECTION: trul provides only temporary relief and is used by Where possible, the best approach is to prevent public agencies until other measures can be iulple- nlosquitocs from breeding by elilnillating breeding rllellted. sites. This may be accomplished by such Actions as C'omrllonly available insect repcllcnts may be filling, dumping, ditching, or otherwise draining useful if it is necessary to he in an area at twilight the source. Around tile home, slake certain that; all- where very large numbers ol'this species exist. Marin/Sonoma Mosquito Abatement ,.! strict 556 N . I.1cDowell Blvd. - Petaluma- Calif 94952 ( 707) 762-2165 MOSQUITO BIOLOGY Culex pipiens pipiens Introduction Morphology Culex pipiens is an indoor pest mosquito that breeds Egg: White when first laid, darkening to a light brown primarily in polluted water sources. It is commonly within a few hours. Individual eggs are 1.0 mm in called the house mosquito. length, elongate with a larger blunt end that tapers to a smaller pointed end. Eggs are laid together on end Classification forming a boat-shaped raft that floats on the water Phylum Arthropoda(crustaceans,spiders,insects) surface. Class Insecta((insects) Order Diptera(flies) Family Culicidae (mosquitoes) Subfamily Culicinae Genera Culex !.,i• �1K� Subgenera Culex Species pipiens Distribution Larva: Cuticle is transparent with light brown In North America, Cx. pipiens is distributed throughout sclerotized areas allowing internal organs to be visible. the northern half of the United States into parts of This combination gives the larva a light to dark brown southern British Columbia and Quebec. In California, it color. Larval instars range in size from 1.5 mm for a is confined to the northern half of the state. first stage to 5.0 mm for a fourth stage. The body is divided into three parts: head, thorax and abdomen. A siphon is located on the terminal abdominal segment. Key larval characteristics are (1) siphon not more than 4 to 5 times as long as basal width; (2) siphon hair tuft out of alignment; (3) anal saddle without dorsal spicules; and (4) third and fourth abdominal segments with double hairs. i i �._ i t— - abdomen i �-- \ 3 F thorax \ F head Life Cycle r Adult: Key adult characteristics are: (1) proboscis As illustrated, Cx. pipiens has four distinct life stages: without a white band; (2) basal, broad white bands on egg, larva, pupa, and adult. Depending on top of abdomen;and (3) tarsi all dark. environmental conditions, the life cycle can be completed in 10 to 23 days. ADULT ,lt days to weeksl T VEGGS PUPA 1 to 2 days 2-3 days --�� INA _ 2JILARVA 13t LARVA 41h 71,2 l0 2 days �. 2 10 7 days t� 1 IF Y 3-+ LARVA 2nd LARVA 3rd 1 to 1 V2 days .,-.,l .- Ecolo-g Adult Cx pipiens have four distinct daily activity In northern California, overwintering females leave periods based on light intensity: male swarms, flight winter resting sites in spring and begin depositing eggs activity (host seeking and blood feeding), finding in aquatic habitats. The ensuing generations of resting sites, and resting. females continue to produce and deposit eggs through the summer until late fall. Egg laying ceases in November when females enter winter resting sites and RQ".erylfy does not resume until the following spring. Immature stages (larvae and pupae) appear in early spring and are present in aquatic habitats until late fall. DUSK DAWN Seasonal Cycle-Northern California swarms tooting sites Month: Jan Feb Mar Apr May Jun Jul Aug Sep Oct Noy Dec stage: E E E E E E E E E E. DAY L L L L L L L L L L testing P P P P P P P P P AF AF AF AF AF AF AF AF AF AF AF AF AM AM AM AM AM AM AM AM AM Outdoors, adult female Cx. pipiens feed on both birds E=egg L=larva P=pupa AF=aduttfemale AM=adult male and mammals. Passerine or perching birds such as blackbirds, white-crowned sparrows, house finches, Mating occurs in male swarms that form at dusk. and house sparrows represent a large portion of blood Swarms containing a few to hundreds of males meals. UN \y 6 \\�:F ? ,�ei Faalein.(a25X) orientate over prominent objects (trees, bushes). ho.,h�:�a) "� � Single females fly into the swarm and are pursued by males. After joining terminalia (sexual organs), the pair lands, and assumes an end to end posture. In 15 to 30 seconds copulation is completed, the pair separates, \\\ and they fly away. M Cx. (e osition adult females have an ovi a `a pipiens P 99 \\.: y � K� � � �. F�..,ant(3.Et:) I a bees L'nknc.n(71a)ying) preference for aquatic habitats that contain � � , organic pollution. In urban areas, unmaintained ct.;ck.n(2:4a) swimming pools or artificial containers such as buckets and tires can be a very productive breeding source for During the summer and fall months or when immature stages. populations are.high, females readily enter residences feeding on the human occupants after dark while they Larval Habitats Sleep. Agriculture Indust Domestic Natural dairy sumps containers septic tanks Diseases Vectored rice fields log ponds lawn seepage sumps or ponds of: ornamental ponds cannery waste containers wine catch basinsCy, pipiens is considered a secondary vector of ry waste slaughterhouses roadside ditches sewer farms swimming pools sleeping sickness (WEE and SLE) viruses in California. Cx. pipiens adults have a limited flight range and the virus Protozoan Round Worms majority of the time remain within a mile of the breeding Western Equine Encephalitis bird malaria dog heartworm St.Louis Encephalitis habitat. In the fall or when rural sources produce high Venezuelan Encephalitis populations adult females can move up to five miles Fowl pox from the source. Control Measures Flight range from breeding habitat (miles) Immature mosquito populations can be reduced by a 0 1 2 3 a 5 6 combination of physical and chemical methods. Mosquito Abatement Districts currently apply a Male (daily) ': bacterial protein crystal (Btr), an insect growth regulator (methoprene) and a light mineral oil (GB 1111) to mosquito breeding sites. Adult populations Male (maximum) 1 can be reduced with specialized equipment that dispenses aerosol droplets of a plant extract (pyrethrum). Female (daily) 3 s.• Female (maximum) S t >T Ken Boyce&Susan Maggy,Sacramento/Yolo Mosquito&Vector Control District STATE OF CALIFORNIA—HEALTH AND WELFARE AGENCY PETE WILSON, Gar rror DEPARTMENT OF HEALTH SERVICES - : 714/744 P STREET _ P.O. BOX 942732 SACRAMENTO, CA 94234-7320 ARBOVIRAL ENCEPHALITIS (Mosquito-borne encephalitis) What is arboviral encephalitis? Arboviral encephalitis refers to a group of diseases caused by certain viruses which are transmitted to people by mosquitoes as they bite and suck blood. In California, the most significant of these viral diseases are western equine encephalitis (WEE) and St. Louis encephalitis (SLE). They usually occur in the summer or early fall. Why are they called by those names? St. Louis encephalitis was first discovered in St. Louis, Missouri, as a human disease. Western equine encephalitis was discovered in California as a disease of horses, and soon thereafter was also found to affect humans. How common are these diseases? They are usually quite rare in California, only a few cases each year. But, in years with lots of rainfall and lots of mosquitoes, they can become epidemic with dozens or potentially hundreds of cases. Who can be infected? Anyone who is bitten by an infective mosquito. But, very young and very old persons are more likely to get sick. What are the signs or symptoms? Infection by the WEE virus or the SLE virus usually does not cause any signs or symptoms at all (subclinical infection) and the person develops immunity to the virus which lasts the rest of his or her life. Perhaps one in several hundred people infected develops symptoms a week or two after exposure. These can be very mild (some fever, slight headache, muscle aches) or can become severe (severe headache, stiff neck, and neurologic signs such as convulsions, paralysis or signs of nerve damage) and even fatal. Infants and young children are more vulnerable to WEE, and elderly persons are more likely to get severe illness due to SLE, often resembling a stroke. Are there other diseases that cause symptoms like these? Yes, there are many other diseases similar to WEE or SLE but which are not transmitted by mosquitoes. These others are usually passed from person-to-person, and are caused by other viruses or bacteria. Some of the most common are ccxsackieviruses, echoviruses, herpesvirus, meningococcus bacteria, among others. rr: . + Y Arboviral Encephalitis 2 What should I do if I think I, or someone in my family, might have WEE or SLE? Check with your doctor for special tests needed to identify these mosquito-borne diseases or other diseases which mimic WEE and SLE. Usually, special blood tests are all that are needed for testing. If you are very sick, and need to stay in the hospital, other special tests may be necessary to determine if there is brain or spinal cord inflammation (encephalitis or meningitis). How is the virus spread? In nature, the virus is usually passed back and forth between mosquitoes and small, wild birds. The birds, such as sparrows and blackbirds, carry the virus for a short time in their blood, but usually do not get sick. The infective mosquito carries the virus in its saliva. Mosquitoes pick-up the virus while feeding on the bird's blood, then pass the virus via their saliva to another bird in a later feeding. The type of mosquito that carries these viruses prefers to bite birds, but will occasionally bite people or domestic animals such as horses, causing an "accidental" infection with WEE or SLE. Do all mosquitoes have the viruses? No, the large majority do not and the chance of their picking up the virus from a temporarily-infected bird is slim. However, a person can be exposed to hundreds of mosquito bites in a short time, so the chances of being bitten by an infected one are increased in an area where the natural virus cycles are active. Can I get infected from other people? No, there is no evidence that people are infectious for other people. However, because doctors cannot at first tell what the cause of the encephalitis or meningitis symptoms is, sick patients are usually kept under special isolation precautions in a hospital, to be sure they don't have some other, contagious disease. Do other animals get infected or sick, besides people? Yes, many other animals get infected and might get sick, although this is not very well known for many species. Horses and related equines can get WEE and become quite ill or die, therefore veterinarians commonly vaccinate horses to protect them from the disease. Could I get infected from a sick horse or from contact with infected birds? No, not from just touching or being near them. Only if blood from a sick animal were actually injected into your body could this possibly happen. Is there a treatment or vaccine for people? There is no specific treatment, and it has not been feasible to develop a vaccine to protect people, as yet. /1n 9 , Arboviral Encephalitis 3 Where do mosquitoes come from and how can 1 avoid them? Mosquitoes breed (lay eggs, which develop into larvae, then pupae, then new adults which then seek a blood meal) in many bodies of water, especially in somewhat polluted water such as irrigated pastures, waste water, puddles, in old, discarded tires, poorly maintained swimming pools, fish ponds, gutters, outdoor potted plants, cans and trash in garbage dumps, slow-moving streams and flooded marshy areas. How can I avoid mosquitoes and prevent infection? 1. Remove free-standing water outside your home, to eliminate mosquito breeding sites. 2. Screen your home to prevent mosquitoes from getting inside. 3. Avoid exposure to mosquitoes, especially at dawn and dusk when they are most likely to bite. It is especially important to protect infants and young children. 4. When outside, avoid mosquito bites by wearing protective clothing and using repellents with D-E-E-T, for example. Always use repellents according to label directions and use sparingly on children. Where can 1 get more information? Contact your local public health department or your local mosquito abatement district for more detailed information, published brochures, or referral to pamphlets, medical literature or books about this subject. MOSQUITO BIOLOGY Culex tarsalis Introduction Morphology Culex tarsalis is a medium-sized mosquito that was first Egg: White when first laid, darkening to a light brown described by Coquillett in 1896. It is commonly called within a few hours. Individual eggs are elongate with the encephalitis mosquito because it is considered the one end bluntly rounded and the other pointed. They primary vector of western equine encephalitis virus. are 1.0 mm long. Eggs are laid together on end forming a boat shaped raft that floats on the water Classification . surface. Phylum Arthropods(crustaceans,spiders,insects) Class Insecta (Insects) Order Dipiera (flies) mK� , Family Culicidae (mosquitoes) Subfamily Culicinae •�� Genera Culex Subgenera Culex Species tarsalis Distribution Larva: Larvae have three body parts: head, thorax, and abdomen. A spiracular apparatus or siphon is In North America, Cx. tarsalis ranges from western, located on the terminal abdominal segment. Larval central, southern U.S. into Southwestern Canada. In instars range in.size from 1.5 mm for a first stage to 5.0 California, it is collected from all 58 counties from sea mm for a fourth stage. Color varies from clear to green level to 9,890 feet. with external sclerotized areas a light brown. A key larval characteristic is a siphon tube with four or five pairs of hairs nearly always in line. '^-.x�M t' "}Yy�r;��\y 1 .t��AJ`' fh l{.,.Siti- u/ f��_y. "i..7- siphon > Z_zo -j 7 ..�.__�� abdomen 34 '.` ��\ t /, t-thorax Life Cycle % Adult: Key adult characteristics are (1) a complete pale median band on the proboscis; (2) white stripes As illustrated, Cx. tarsalis has four distinct life stages: along the outer surface of the hind femur and hind tibia; egg, larva, pupa, and adult. Depending on (3) pale bands overlapping tarsal joints; and (4) dark environmental conditions, the life cycle can be inverted v-shaped marks on the abdominal sterna. completed in 12 to 18 days. Ato T 1 'rfGc)'S :0 -eeLs PUPA 2 - 3 days EGGS 7 to 2 days LARVA tth ,:.}/� _ _ f 4_ 2 to 7 days ` 2 Tp/� LARVA )st \ 1 1/2 t0 2 days ,L-M. LARVA 3-d / •-'•" I to 2 days LARVA 2nd i -\3 7 to 1 112 rays 1 Ecology Adult Cx. tarsalis have four distinct daily activity periods based on light intensity: swarming, sugar or host In northern California, Cx. tarsalis population growth feeding, finding refugia, and resting. begins in spring and continues until fall. During early October a few adult females start depositing fat bodies. By late November the majority have suspended New reproductive activity (reproductive diapause). In late u,,. fall males disappear and the population overwinters as inseminated diapausing females. They overwinter in natural refugia such as animal burrows, tree stumps, DUSK DAWN hollow logs, brush piles, and wood rat nests. During 11t)t swarms rtarinp onto January and February, the reproductive cycle resumes in a few overwintering females until by March the majority are not in a reproductive diapause. The first egg batches are laid in early spring. DAY Seasonal Cycle-Northern California Month: Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Stage: E E E E E E E E E Cx. tarsalis females feed on a variety of hosts. The L L L L L L L L L L majority are birds. Passerine or perching birds such as P P P P P P P P P blackbirds, white-crowned sparrows, house finch and AF AF AF AF AF AF AF AF AF AF house sparrow represent a large portion of blood DF DF DF DF DF meals. AM AM AM AM AM AM AM AM AM P....ri'. (J1J%J N �\ . E-egg L-larva P= u a AF-adult female AM=adult male .A �� 9 P P �tl DF=Diapausing females bold=peak populations �� ��Q\ a,.s(z.ox) Mating occurs in male swarms that form at dusk, swarms containing a few to hundreds of males orientate over prominent objects (trees, bushes). c.rr;. lrtsXJ � � Single females fly into the swarm and are pursued by males. After joining terminalia (sexual organs) the pair (21JX) lands, and assumes an end to end posture. In 15 to 30 Hw,. (DDX) , Dop seconds copulation is completed, the pair separates, (2.6XJ3, u,n (o.,%) and they fly away. J.cknserr(rzsxJ c7Jcl.a ftsXJ Ola.r bkd, (5.7X) Cx. tarsalis females have a marked oviposition preference for certain aquatic habitats based on visual Diseases vectored cues, olfactory attractants, and fermentation of organic material. �y Culex tarsalis is the primary vector of WEE and SLE Larval Habitats viruses (sleeping sickness) in Sacramento, San Agriculture Industry Domestic Natural Joaquin, and Imperial valleys of California. pastures containers septic tanks wetlands rice fields log ponds omamentat ponds lakes&ponds Virus Protozoan Round worms row crops sumps containers rein pools&springs duck clubs gravel pits catch basins freshwater rnarshes Western Equine Encephalitis Avian Malaria None non-row crops roadside ditches snow pools St.Louis Encephalitis orchards meadows seepage drains California Encephalitis canals Jamestown Canyon (Lab) hoof prints Venezuelan Encephalitis (Lab) water(roughs Turlock Hart Park Flight range for host-seeking females population is 1.75 Lokern to 3 miles a night. They can move up to 7 miles in two evenings. Control Measures Flight range from breeding habitat (miles) Immature mosquito populations can be reduced by a t a5 6 combination of physical and chemical methods. Biological control agents are mosquitofish and Hale (daily) , naturally occurring beneficials such as backswimmers, beetles, and flatworms. Mosquito Abatement Districts \ \ \\ s currently apply a bacterial protein crystal (BtO, an Hale frd[tml;m) ��\ ��: insect growth regulator (methoprene), and a light mineral oil (GB 1111) to mosquito breeding sites. Adult Female fcailyl 7 populations can be reduced with specialized equipment that dispenses aerosol droplets of a plant Female fmax,munl \` '•��� �� � �r extract (pyrethrum). I . . Ken Boyce&Susan Maggy,Sacramento/Yolo Mosquito&Vector Control District California Mosquito Control Association -MOSQUITO . NOTES CALIFORNIA SALT' MARSH MOSQUITO / LIFE CYCLE Mosquitoes have four distinct life stages - egg, larva, pupa and adult. The female California Salt Marsh Mosquito deposits its eggs singly on the mud along the edge of receding tide pools. The eggs re- main unhatched usually until the next late fall or winter rains and high tides. Eggs can remain alive for several years and not all will hatcli with the i 1 next flooding. After suet, marsh, flooding, most / \ eggs may hatch into larvae within a short period of \ water contact. The larvae feed on small organic particles and microorganisms in the water. Full grown larvae molt and become pupae, or tumblers, in which Ir.des squumiger stage many changes occur that lead to development C�NERAL INFORMATION of a winged adult within the pupal case. ,1. squam- 49er is single brooded with the larval stage usually I e(les squuniigcr is commonly called the Cali- maturing during winter and the adults emerging fornia Salt Marsh Mosquito because it breeds ex- from mid-February to May, which stage may live elusively in the salt marshes along the California for up to three months. coast. It is medium to large size with a grayish or HABITS black coloration. The end segments (tarsi) of the legs have broad white bands. The mixture of dark Female salt marsh mosquitoes are vicious biters, and light scales on the wings gives them a "salt and attacking man and other animals at any time of pepper" appearance. day, but maximum biting activity occurs at twi- This species breeds in salt marsl, waters left by light. They may bite actively at night indoors un- extra high tides or from rains. It occurs only along der lights, but nonnally bite only out-of-doors. The the Pacific Coast from Sonoma County to Baja females are strong fliers, migrating long distances California. It has been the major mosquito problem (up to 20 miles or more) in large numbers. The in the Sall Francisco Bay area within recorded his- males emerge before the females, mate, and usually tory of the area. remain near the marsh. o Q GC(:S t.Af;NIA PUPA AMILT ECONOMIC AND MEDICAL IMPORTANCE BIOLOGICAL CONTROL: This species is not known to be a natural vector Because of the salinity variance and shallowness of disease producing organisms in.California. How- of many of the durable breeding sources for this ever, its vicious biting habits can render areas mosquito, the use of mosquito fish (Garnbusia where it is present virtually uninhabitable for man. affinis) has not been feasible, and other methods Development of some of the lands in the San Fran- have not been developed. cisco Bay area had to await the control of this CHEMICAL CONTROL: species by organized mosquito control. This species can be very annoying to livestock, resulting in re- duction in feeding and in possible injury to frantic develop which can make it necessary to use chem- animals attempting to escape the severe attacks. ical control. Due to the often sensitive ecological - relationships on our marshes, chemical control CONTROL METHODS should be carried out only by trained mosquito PREVENTION AND CORRECTION: control personnel. Control agencies have know- The most important method of controlling salt ledge of the proper compounds and application marsh mosquitoes is to eliminate or modify the techniques to assure minimal environmental side specific water areas in the salt marshes where the effects. larvae occur. This may be accomplished by ditch- Insect repellents may be useful if it is necessary ing, which permits the water from very high tides to be in an area where large numbers of these or rains to flow back into the bay or ocean. Levees adults are present. and tide gates may be put in around marsh areas to prevent inundation by tidal water and still per- mit accumulated water to run out. Filling of some low areas may be useful in eliminating standing water as breeding sources. Many of the former sites of A. squarniger breeding in the San Francisco Bay area have been permanently eliminated by filling and draining of the salt marshes during extensive commercial and residential development. Marin /Sonoma Mosquito Abatement District 556 N . McDowell Blvd. Petaluma , Calif 94952 ( 707) 762-2165 800-231-3236 PESTICIDE INFORMATION METHOPRENE II O GENERAL INFORMATION thoracicotropic hormone (PITH), the corpus allatum synthesizes juvcr le hormone, and the prothoracic gland Dethoprene is a man-made chemical that mimics the secretes alpha-ecdysone. The changing concentrations of biological activity of insect juvenile hormone (JH). When these hormones are responsible for insect molting and present during critical development periods, it interferes metamorphosis. with normal insect development process. Synthetic juvenile The insect neuroendocrine system is driven by physical hormone analogs (JHa) are commonly referred to as stimuli. Insects have receptors in the epidermis that juvenoids, insect growth regulators(IGR'),third-generation monitor its growth rate and stumulate neurosecretory cells pesticides or biorationals. In 1934, Wigcleswortlt in the brain to produce PTTH, a brain neurohormone. discovered that an unknown "factor" controlled insect PTTH is released by the corpora cardiaca and travels to the molting and metamorphosis (transformation from lama to corpus allatum gland by neural pathways. Its presence adult form). It was not until 1967 that H. Roller deter- stimulates the corpus allatum gland to synthesize and mined the chemical structure of the factor, which was secrete Ivgh concentrations of juvenile hormone into the named juvenile hormone. It is now known that JH not hemolymph (insect blood). In the hemolymph, JH binds only controls insect molting and metamorphosis, but also to proteins. PTTH is also released into the hemolymph. reproduction and embryonic development. Methoprene is Its presence stimulates the prothoracic gland to secrete Wgli used in mosquito control against floodwater mosquitoes levels of Alpha-ecdysone into the hemolymph. Once it and leas been formulated into liquids and slow release reaches the malpighian tubules and fat body, Alpha-ecdy- briquets. sone is converted into the hormone Beta-ecdysone. Blood concentrations of Beta-ecdysone remain high JH AND METHOPRENE CHEMISTRY with surges, but JH titers decline during insect develop- ment. In the larval stage, JH concentrations remain Wgh, Five insect-produced JHs have been discovered: JHI, allowing the larvae to grow, molt, and produce new larval JHII, JHIII, JHO, and iso-JHI. The function of JHI and cuticles. The presence of JH prevents the expression of JHII in most insect groups is to control metamorphosis. adult characteristics during the larval stage. When the JHIII is a gonadotropin (hormone that controls gonads). corpus allatum gland ceases secreting JH, the declining The role of JHO or iso•JHI is undetermined. Juvenile blood concentrations of JH allow the larvae to form a pupa hormones are sesquiterperiod hormones. cuticle. When juvenile hormone disappears from the hemo- The chemical name for methoprene is Isopropyl lymph, the pupa transforms into an adult with adult (2E, 4E) - 11 - methoxy -3, 7, 11 trimethyl .2, 4 dodeca- cuticle. dienoate. Methoprene is a terpenoid. It is composed of 19 carbon atoms, 34 hydrogen, and 3 oxygen. The molecular MODE OF ACTION structure is a saw-tooth chain of carbon atoms with methyl branches attached along the chain. Its molecular and Methoprene is teratogenic to mosquitoes (disrupts chemical structure is very similar to that of natural insect normal insect developmental process), but its mode of juvenile hormones. To date, over 5,000 JHa have been action is unknown. One theory by Williams and Kafatos is produced with broad to narrow ranges of activity against that changing juvenile hormone concentrations activate or insect pests. inactivate repressor genes (DNA) that determine larval, pupal,or adult characteristics. The presence of methoprene INSECT NEUROENDOCRINE SYSTEM prevents a progressive change from one developmental stage to the next,thus maintaining the status quo. The insect neuroendocrine system is composed of For a mature insect larva to metamorphosize into a three glands: (I) corpora cardiaca, (2) corpus allatum, normal pupa and then a sexually mature adult,the flow and and (3) prothoracic. The corpora cardiaca releases pro- exposure to JH must cease. if JH or JHas persist in the environment of an insect during the critical period of meta- The mechanism for JHa resistance is unknown. It may morphosis, it will disrupt the normal developmental process be based oil the two mechanisms for the natural breakdown by (1) prolonging the larval stage, (2) forming larval-pupal of JH: (1) hydrolysis of the ester group or (2) hydration intermediates, or (3) forming pupal-adult intermediates. of the epoxide group. Hydrolysis of the ester is a common The critical period for most insects is the first half of the metabolite because the JH molecule is attacked by general last instar. The expression of pupal characteristics depends carboxyesterases produced in the fat body. They cleave the on the absence of JH during this critical period. JH into molecules that have no biological activity and are When juvenile hormone is applied to aquatic habitats excreted by the insect. of mosquito larvae, its affect is inapparent. Larvae continue to feed and appear to develop normally,but when SAFETY they metamorphosize into the pupa or adult stage,morpho- logical abnormalities are manifested. In mosquitoes, eight Methoprene is a very safe material. It has a very low major physical effects occur from excessive concentrations mammalian toxicity. Oral LDso is greater than 10.000 of juvenile hormone during the critical development period. mg/kg. There is no evidence of carcinogenic (cancer- They are (1) extranumerary larval instars - fifth larval causing), teratogenic (birth defect causing), or mutagenic stage, (2) 4th instars appear normal, but die before pupal (genetic defect causing) properties. It is not a cholines- phase, (3)pharate pupae-pupae not out of larval exoskele- terase inhibitor or allergen. tons, (4) albino pupae - pupae die before or after larval molting, (5) deformed pupae, (6) normal appearing pupae ENVIRONMENTAL IMPACT but dead, (7) adults attached to pupal case, and (8) adults abnormal or normal. Unlike organochlorine (DDT, methoxyclilor) com- h„Kbt..c",p pounds that can persist in the environment for decades, eeX.uef.t-N u •:.=•u��=_w ' \kc methoprene is bio-degradable. In freshwater systems, v, methoprene will breakdown in less than 48 hours. It is also unstable in sunlight, at higli temperatures and in polluted water(bacteria break it down). ` t At recommended application rates, it has little impact .,;,a on non-target organisms because of this rapid breakdown ,„„y,y,,,yy a".,i."„ tarp,nq elate c :r.t+e^f et no'+<nes.• WA s Az *;AL - 's i" ADULT process. At higher than field application rates used in Yi IY,:t,finf,a,pt.M,Ur• 'p.',.ctnen,, I Y1 p4, ftM.fu """'" M,'""' '"•"e' mosquito control methoprene will disrupt the growth S r.er on,•.••royson. aner,n:f,[+en,na,al:. cvt,c: IY"m, ,nte ev,t ,ta , and development of other aquatic organisms that undergo Normal Cevelopnent of a mosquito through it's life Lytle. molt cycles under the control of JH (micro-crustaceans, crayfish,crabs,and aquatic insects). rww eVK d <�a FACTORS THAT MAY REDUCE THE EFFICACY OF METHOPRENE n.Y4,.be.> °`" " H� 1, Life stage - methoprene is only effective when applied w.ro• to 2nd - 4th instar larvae. It has no effect when e�;'o ner.ntf applied to pupae. LkVAL STALES PUPA ADULT Ylgn.t Alf snt.-4-M.1,r. P11P Nip rc......Yt9Y 2. Mosquito genera - Aedes species are very susceptible. a��,;y ,. 7- •. f,"M.Wwl ?,.tia tfrwet �`�. -�-�K�,,�,y ,�,�„ t,ft,r."t,t tf,"I.0 tarn. r[,<lr fo�6• tr.nf hen i�Y� net[,,l if rwf[..,N rtn,..t re+N,rnf Ut ,Ivlt 1Lpf. Culex species are moderately susceptible. Anopheles tntroduttion of , species are unaffected. juvenile horaone analog, Y.ethoprene (AltosiC), that disrupts the netarorphosis eyCle. RESISTANCE 3. Timing - methoprene must be present during the critical development period which is the first half of last instar. The mode of action for methoprene and natural 4. Degradation - methoprene molecule breaks down in juvenile hormone is the same; both effect insect develop- ment. Insects possess bioc)lemical mechanisms to break sunlight, high temperature and file presence of bac- feria. In freshwater systems it is active for only 48 down natural juvenile hormones, increasing the potential for developing resistance mechanisms to JHa's. At present, ]tours. no mosquito populations are known to be resistant to JHa's. S. Water flow - strong water currents may remove material Laboratory strains of fruitflies and houseflies have been from target area. bred that demonstrate some resistance to the biological activity of JHa. PESTICIDE INFORMATION PYRETHRINS 1 i •. • 7� \ t J, R • ♦ ` PYRETHRUM CHEMISTRY GENERAL INFORMATION The toxicity of pyrethrum is the result of siz chem- ically related compounds: pyrethrin I,pyrethrin II,cinerin Pyrethrins are a group of naturally occurring com. cinerin 1, cinerin II, jasmolin I. and jasmolini II. All are pounds with insecticidal activity that are extracted from esters (a combination of an acid and an alcohol). They are the flowers of a plant belonging to the genus Chr.•sonthe- classified into one of two factions based on the type of acid MUM. Current commercial production of pyretlirum is they contain. The chrysantl;emic acid esters are the from C. cinerariaefolium (Dalrn2i n pyrethrum). a plant pyrethrin I faction (p)-rethrin I, cinerin I, and jasmolin I). indigenous to Yugoslavia. Annually, more than 40.000 The pyrethric acid esters are the pyrethrin II faction tons are produced worldwide. Four countries account for (pyrethrin 11,cinerin 11.and jasmolin II). 95% of the production: Ken\•a, Tanzania, Ecuador; and 'When C. cinerariaefolium flowers are homogenized in a Rwanda. Cultivation is best in a Nvartn and wet equatorial petroleum solvent, a dark viscous liquid concentrate called climate, between an altitude of 6,000 and 8,000 feet. oleoresin is produced. This typically contains approx- Pyrethrins have been used to control mosquitoes since the imately 307c, pyretltrins in the following proportions: 1880's. They have been used in sprays,pcv-,ders,mosquito pyrethrum I (1 1.417c), pyrethrum II (10.59o'), cinerin II coils, aerosol bombs, and more recently; in truck-mounted (3.5ic), cinerin I (2.21;c),jasmolin I (2.29c,), and jasmolin II ultra low volume(ULV) applications. (2.2ic). Algae, stoneworts, mosses; horset2i's, ferns, cycads. ginkgoes, conifers, and flowering plants are classified in the MODE OF ACTION kingdom Plantae (photosynthetic autotrophs). C. ciner- ariaefolium is a flowering plant (division Anthophyta)that Pyrethrins are neurotoxic (disruptive to nerve belongs to the class Dicotyledonae (dicots), fanuly Aster- function) to insects. Their biochemical effects are not aceae (chrysanthemums, sunflowers, lettuces, and dande- completely understood but the action of pyrethrins is lions). The genus Chri-anrhemum contains more than excitatory and then blocking. The site of pyrethrin activity one hundred species but only a few have insecticidal appears to be at the nerve cell membrane which controls properties. the flow of nerve impulses across the neuron. Pyrethrins The C. cinerariaefolium plant looks like a field daisy. are thought to somehow modify the membrane's control It is a perennial with unbranched hairy stems. The plant mechanism (sodium ch2nnel gates), so that nervous stimu- can grow from 18 to 24 inches in height over a 2 to 3 foot lation remains in a continuous state. This results in intense area. The foliage is a light bluish-green with silvery leaves repetitive activity of both nerve fibers and sensory organs. 6 to 12 inches long. Flowers are 1'/a inches across with After this initial excitatory action, the nervous activity white petals and a central disk of yellow petals. slows, and is followed by a complete synaptic nerve block. The action of pyrethrins is classified into three effects: SYNERGISM (1) knockdown, (2) paralysis, and (3) lethality. pyrethrins are fast acting; insects are affected in one to a few minutes To enhance natural pyrethrins' toxicity, either after exposure. This is termed knockdown and corresponds piperonyl butoxide (PBO), sulfoxide, propylisome, or to the chemical's excitatory action on sensory and Tropital are added to formulations. These materials peripheral nerves that are exposed initially. In some increase knockdown rate, kill, and cause the effects of populations, a few individuals or species may be readily pyrethrins to last longer,thus acting as synergists. They are knocked down but recover before the paralysis phase. thought to work by interfering with the insect's ability to After the material is absorbed,paralysis.occurs. This effect detoxify the pyrethrum. Another mechanism may be to corresponds to the nerve block phase of the pyrethrin's increase cuticle penetration, allowing toxin to reach the action. The cause of death is unknown. nerve cell membrane faster. The ratio of synergist to Physical symptoms of insect pyrethrin toxicity are pyrethrum is important;not enough could result in reduced stimulation, loss of coordination, paralysis and death. knockdown, while too much may increase knockdown but In mosquitoes that survive,leg loss (chemical amputation) reduce kill. Most formulations are 3 to 7 parts synergist to is common in post-treated populations. Appendage losses 1 part pyrethrin. PBO is the most conrnon synergist added range from a portion of a leg to all six legs. These to natural pyrethrins. mosquitoes have difficulty in assuming a resting or feeding position and probably do not survive for any great length of SAFETY time. Pyrethrum is a very effective insecticide against a number of insect pests and is easily formulated into a RESISTANCE variety of products, but its greatest attribute is its safety. -Pyrethrins have a low mammalian toxicity. Oral LD5o is The mode of action for pyrethrin and dichlorodiphenyl about 1500 mg/kg. There is no evidence of carcinogenic trichloroethane (DDT) is similar in that both disrupt the (cancer causing), teratogenic (birth defect causing), or ion transport system of the nerve cell membrane. This mutagenic (genetic defect causing) properties. It is not a similar mode of action increases the potential for a cholinesterase inhibitor; however, a few allergic reactons, pyrethrum/DDT cross-resistance insect strain. Some wild asthma and dermatitis, have been reported. These populations of Aedes oeeypti, Culex tarsa s, and Cx. responses are a result of flower impurities in the liquid pipiens mosquitoes have been reported resistant to both mixture and not a reacti6n to the pyrethrin molecule. The chemicals. Also, laboratory experiments have been pyrethrum plant is related to ragweed, a common allergen. conducted which indicate mosquitoes resistant to DDT are less susceptible to natural pyrethrins. The mechanism for IMPACT ON THE ENVIROI\.NIENT this resistance is thought to develop in either of four possible ways:(1)detoxification, (2) decreased absorption, Pyretlirins are non-persistent and biodegradable (3) decreased penetration, or (4) reduced nerve sensitivity. compounds. They are photolabile (broken down by Mosquitoes have been found that detoxify pyrethrins by light), so residues aze not detectable 12 to 24 hours after oxidative metabolism. In this pathway, enzymes cleave an application. There is very little impact on non-target a section of the molecule, removing a group of chemicals organisms because of this rapid breakdown process. from either the acid or alcohol moiety (part) of the pyrethrum molecule. This results in a product that is no longer toxic to the insect and is then further metabolized. M California t`tosquito l 01111.1 AM P 04 A y �1.A 0 PHE40 T N s - A SNOW 1110SOUITU This species is found throughout the Western United States and Southwestern Canada. In C'ali- fornia it occurs in flood waters at sca level and in the foothills oh the Coastal Range from Southern California to Humboldt County anti certain areas of the Central Valley to high elevations in the Sier- ra Nevada Mountains. LIFE E CYC1,1•: h:IVC I'Mir distinct hte �I:igcs :is '-',c!1 tlelow. TIlc laMll and pupal slar;cs :Ire dcperluent on water for their survival and dCVCInpIl1C111. The eggs are laid singly on the nim-l-,ins ()Drivers, streams, shallow lake areas, depressions formed from the melting snow, hoof prints and grassy nica- dow pools. The eggs hatch when these areas are flooded. All of the eggs )n;ly not h;ltch on the first .treks increpilus flooding, and unhatched eggs can survive for sever- al years. GFINE,11AL INFORNTATIUN The eggs hatch into larvae which then fecd on small organic particles ailed microorganisms (tvlrs incrrl,ilns is often referred to ::s a "s:low­ in tltc %WILT, larvae limy h,rng from file mosquilo because it may occur in fools flooded by water surface by the lip of their tail (siphon) when melting snow. It ;Ilso occurs in floodwater habitats they reed, or they Inay feed along the hottoul, but in the valley Doothiils and along the coast. must return to the water surface to hrc;i1hc. At the It is of* medium sire, dark brown to brown in end of the larval stage, the mosquito molts and be- color, with hnght white hands on the hind tarsi comes the aquatic pupa (tumbler). 'I he pupa is ac- (Dect) and white cross bands on they pointed ando- tive only if disturbed, for this is the. —resting" sta>:e nlen lh:It widen to lateral spots appearing brighter where the larval fonn is transformed Into that of than the h;lnds themselves. The wings have conspic- the adult. This takes about two days during which uous pale sc:+lcs confined to the front portion of tune feeding does not occur. When the lransforma- the wing that separates this mosquito From Av,lp.s tion is completed, the new adult splits the pupal fitchii, which has pale scales heavily sprinkled all skin and emerges, This often occurs on moist soil over the wing. Both of these mosquitoes are found when pupae are stranded by rec, dill" waters. Un- in the saute habitat in some locations. Miles re- der optimum conditions development from egg to scmble the females except they have long palpi and adult tnkcs about three weeks. Ilowcvcr, all mos- hushy antennae on (heir head and "claspers" oil quito developmental times are dcpcilklcllt on the their abdomens. temperature of the water in which they develop. __10 00�0� � • EGGS LARVA PUPA ADULT Littic is known agent the life cycle ol*iliis n!c�s CONT11.01, METHODS quito, but generally Ilcc• eggs Ic,!Ic1t from Janu:ccv to May depending on the :dlitude and weather condi— tions (snow melt and 1:1int'all). Adults may appear 1 he prevention of this mosquito is difficult as from February to July. In mountainous are::,, the its ahundance is dependent upon file extent of larvae, pupae, and ad!clis of .irclrs ;ac:rc•lcilres :ire flooding occuning in winter and sprang of the year. uftcn found in association with sevc,.d after In many recreastional areas, ph;si,:d fcatures are lies 01'.1cdc s. prescrved for nalural henuty, tills the full use of souic•e reduction mclhods is not l*,:; .!hle. Draining II NiiITS or (thing small ponds and potht,ics t%w reduce iocal The adult females bita durhig tic d:iv and do populatio!!s substantially where it is �•nvironment- not seem to show inuch prcfL rencc for :,hack or ally sound. bright sunny areas. As they are persistent bit::rs cdf 1310 LOG ICAL CONTROL: man, these. mosquitoes can he very annoying to people visiting rccrralional areas during the Tic stocking of mosquito fish, t:uncicusiu uJ]1nis, ,unimrr months. The :!dull fc•malca apparccitly dU in areas where the Icn!peratum ptin!its, tiucic as not fly very far fn��;i tl!c�ir larval habil:,l. Sevcr:il some coastal i:chitats, is in cfl•cctivc nicans ul ron- observers, while he,n� hitien by female musy;, trot. Other mosquito eating fish nt!};hl he used in tors, have noted ui:!Ir niosquifocs Ilying nr.:uhy. sonic areas, but the use of then: fish is sill in the Males feed on ncci:.,, :incd pi:!nt juices. Fcmal x experin!cnlal stage. may also feed on plant juic-2s, hill usi!aily ,ien;t CHI:MiCAL CONTROL: have a hlood meal in ordvi to develop tit it Due to the often delicate ccotot;ic.il h:dances of ECONOMIC AND NiE;DICA1, 1l\lP()RTAN(:E some ponds, chemical control mclhods should he carried out by tr:!ined mosquito ;ihitcment or This mosquito is prima!ily a pest mnsgccito in Health dcpartmcut persccu,:cl. These. officials have recrc':!tiOnal areas. ibis not Known to transmit any knowledge of the proper compounds and applica- disc:,se in nature. however, this species cocdd pos- Boil techniques to assure mini,n;d environmental sihly transmit Venczucl:m F(juino Lnccp1mlitis side effects. Public health agencies .,re generally (VEF) if it become:: esf.1h1i;iicd in C.111forr;1a• able to provide information and assistance where organized mosquito control is unavailjl)le. It is important to remember that chemical con- trol provides only temporary relirf :,nd is used by public agencies until other measures can he imple- mented. Commonly available: insect repellents may he helpful to people visiting areas'whcre this mosqui- to is present. Morin/sonoma Yosquito Abatement District 556 S . McDowell Blvd . Petaluula , Calif 94952 ( ';07 ) ;62-21.65 California Mosquito and Vector Control Association, Inc. MOSQUITO .. NOTES LIFE CYCLE IMosquitoes have four distinct life stages; egg, larval, Ipupal and adult as seen in the illustration. The female Aedes dorsalis deposits its eggs singly on the mud along the edge of receding tide pools. Winter is usually passed in the egg stage. The eggs hatch during the first warm weather of spring or during subsequent re-flooding of the ` 1 2 marshes. This often results in multiple generations of !1' mosquitoes emerging during the summer. Eggs can remain rt+ viable for several years and do not all hatch with the next �,. V ` flooding. After marsh flooding,most of the eggs hatch into larvae within a short period of time from water contact. The larvae feed on small organic particles and micro-organ-isms suspended in the water. Feeding may take place either at the bottom or near the water surface. The larval stage can last from 5 to 14 days, depending on the temperature. l l Breathing takes place at the water surface and is t accomplished by means of orienting upside-down with the tip of their tail (siphon) pointing up. At the end of Aedvs dursrilis the larval stage, the mosquito molts and becomes the pupa (tumbler). The pupa is active only if disturbed for this GENF,RAL INFORMATION is the resting stage where the larval form is transformed into that of the adult. This takes about two days during Aede.s dorsalis is commonly called the pale marsh mos- which time feeding does not occur. When the transfor- quito because of its whitish-gray appearance. This species oration is completed, the new adult splits the pupal skin breeds in coastal salt marshes, brackish waters of the and emerges. Under optimum conditions development from Sacramento-San Joaquin Delta, and some inland lakes of egg to adult takes about 7-10 days. However,all mosquito Northern California. This is a major pest mosquito in the developmental times are dependent on the temperature and San Francisco Bay area. Adults are a medium size mosquito food values of the water in which they develop. Aedes with yellow to straw coloration and a long white band seen dorsalis can produce continuous broods through the spring from above. The end segments (tarsi)of the legs have broad and summer having 8-12 generations per year. white bands. The wings have narrow white and dark scales,having a "salt and pepper"appearance. This species is found throughout most of the United HABITATS States, excluding the Southeast. In California distribution is primarily coastal, being common along the western Fenrile ;cedes dorsalis are vicious biters, attacking border of the State. human beings and other animals at any time of the day or EGGS ',I' LARVA PUPA ADULT night, but are most active toward evening or on calm ocean. Levees and tide gates may be put in around marsh cloudy days. The females are strong fliers, dispersing long areas to prevent inundation by tidal water and still permit distances (up to 20 miles or more); sometimes males accumulated water to run out. Filling of some low areas accompany the females on these flights. may be useful in eliminating standing water as breeding sources. Many of the former sites of Aedes dorsalis ECONOMIC AND MEDICAL IMPORTANCE breeding in the San Francisco Bay area have been perman- ently eliminated by filling and draining of the salt marshes This species is known to harbor California Encephalitis during extensive commerical and residential development. virus in California. However, its vicious biting habits can BIOLOGICAL CONTROL: render areas where it is present virtually uninhabitable for man. Development of much of the areas in the San Fran- Because of the salinity variance and shallowness of many Cisco Bay area had to await the control of this species by of the durable breeding sources of this mosquito, the use organized mosquito control agencies. This species can of mosquitofish (CamLusia ajfinis) has not been feasible, be very annoying to livestock, resulting in reduction in and other methods have not yet been developed. feeding and possible injury to frantic animals attempting CHEMICAL CONTROL: to escape the severe attacks. Problems with drainage or prevention may develop which can make it necessary to use chemical control. CONTROL METHODS Due to the often sensitive ecological relationships on our PREVENTION AND CORRECTION: marshes, chemical control should be carried out only by The most umportant method of controlling salt marsh trained mosquito control personnel. Control agencies mosquitoes is to eliminate or modify the specific water have knowledge of the proper compounds and application areas in the salt marshes where the larvae occur. This may techniques to assure minimal environmental side effects. be accomplished by ditching, which permits the water Insect repellents may be useful if it is necessary to be in from very high tides or rains to flow back into the bay or an area where large numbers of these adults are present. t't,J I RALM InrUt(mNI IUN Bti The parasporal bodies are classified as: (1) large, (2) bar, and (3) high density. The large parasporal body is the least electron dense, is round to polyhedral and contains a 27 kilodalton (kDa) protein. The bar-shaped parasporal body is moderately electron dense and contains .. .... a 65 kDa protein. The highly electron dense parasporal - body is spherical and composed of 128 and 135 kDa 0j proteins. Worldwide, there are 19 subspecies or varieties of ,,�' .�---- r_• B. thuringiensis. Antigenic properties of the flagella(organs s_.W•49.,.•), �d of motility) are the basis for classification. From these ,a.a.—Gom Xw.ak.1982) 19 varieties, seven different toxins have been identified. They are: (1) alpha-exotoxin, (2) beta-exotoxin, (3) gam- ma exotoxin, (4) delta-endotoxin, (5) labile toxin, (6) water-soluble toxin, and (7) mouse factor exotoxin. Some B. thuringiensis toxins have been commercially marketed and are used to control lepidopteran (butter- fly and moth)larvae. GENERAL INFORMATION LIFE CYCLE As illustrated, the basic life cycle of bacteria involves Bti is an acronym for Bacillus thuri)iI ieilsis subsp. two interlinked cycles: (1) vegetative growth and(2)spor- israelensis serotype H-14, a bacteria that produces protein ulation. During the vegetative growth cycle, bacteria crystals with larvacidal activity against mosquitoes, black reproduce by a process called binary fission,whereby single flies and midges. During a 1976 survey of a small tempor- cell divides into two cells. These daughter cells continue ary pond in the northcentral Negev Desert of Israel, Dr. J. to divide into other cells until they enter the sporulation Margalit discovered numerous dead mosquito larvae. In phase. In this cycle, a thickened wall oval or spherical the laboratory, a bacteria culture was colonized from shaped structure develops within the cell wall of the Culex pipiens complex larvae, water and mud collected bacteria. This structure is called an endospore and is the from this pond by L.H. Goldberg. A bacterial colony from dormant stage of the bacteria. Under favorable environ- this isolation was then sent to the Pasteur Institute in Paris mental conditions the endospores germinate and develop where Dr. H. deBarjac identified it as B. thuringiensis subsp. into new vegetative cells. In addition to endospore forma- israe/ In the five kingdom classification system, bacteria and enti`' tion during sporulation, the Bti bacteria produces two to three irregular-shaped protein crystals. blue-green algae are considered to be in the superkingdom Prokaryota (single-celled organisms with no nucleus or other membrane-bound organelles). The Prokaryote is Vegetative :.Sporulation growth cycle divided into two subkingdoms: (1) Archaebacteria (meth- , anogens, halophiles, and thermoacidophiles)and (2) Eubac- .. 3 l teria (Gram-negative and Gram-positive forms). The Eubacteria are further subdivided into three divisions: (1) Gracilicutes (Gram-negative, thin wall), (2) Firmicutes or .� (Gram-positive, thick wall) and (3) Tenericutes (Gram- negative, wall absent). Bti is classified in the subkingdom Eubacteria and division Firmicutes. } As diagrammed, the Bti bacteria is a rod-shaped ? organism which is 3 to 5 microns in length and 1.2 to 1.5 i 0 microns in width. It is aGram-positive bacteria(Cram stain _.• /� r• �� ,emlronment t ;r differences are a result of cell wall structures). On sporula- 4 t tr tion, Bti forms an endospore and produces three parasporal bodies (protein crystals) bound by a fibrous envelope. `/f �s f Mature spore ;1 (From Pelez;r and Reid, 1965) MOSQUITO BIOLOGY Aedes slelTellsis Introduction Morphology Aedes sierrensis is a severe outdoor pest mosquito Egg: - While when first laid, becoming black in a few that was first described by Ludlow in 1905. It is hours. Eggs are elongate with one end rounded and commonly called the treehole mosquito because the other blunt. The surface is covered with a network immatures commonly breed in tree rot holes. pattern. Eggs are.5 mm long. Classification` Phylum lrthropoda(crustaceans,spiders,insects) Class Insecta insects) Order Diptera�tiies) Family Cuiicidze (mcsquitoes) Larva: Cuticile (body wall) is transparent with external Subfamily Cuficinae sclerotized (hardened) areas black. Internal organs are Genera Aedes Subgenera Ochlerotatus visible through the cuticle. Larval instars range in size Species sierrensis from .75 mm (first stage) to 3.5 mm (fourth stage). The Distribution body is divided into three parts: head, thorax, and abdomen. An siphon (air tube) is located on the terminal abdominal segment. Key larval characteristics In Forth America,Ae. sierrensis is distributed along the are (1) evenly spaced pecten teeth, (2) anal segment western coastal states into British Columbia and into not completely ringed by saddle, and (3) long sac-like pars of Idaho, Montana, Wyoming, and Utah. It is anal gills. collected from sea level to 7,200 feet. In California, it has been collected in the central valley, coastal ranee, eastern and western Sierra. It has been reported from 53' of 58 California counties. — Siphon-> "y......_... !.>.. } r abdomens 4-thorax KYT F heed 3 i • - i r i ! ` i W ;--� Adult: Key adult characteristics are: (1) a dark proboscis without a white band; (2) tip of palpus with white scales; (3) small pale bends overlapping leg Life Cycle �`4 joints; and (4) last segment of hind legs white scaled. As illustrated,Ae. sierrensis has four distinct life stages: egg, larva, pupa, and adult. Depending on environmental conditions, the life cycle can be completed in 15 days or may require months. .� { 2 J ` 1 1 y RJ:1LT � J EGG S li 2�EekS - epnth5 - •ice- �� ,1 1 K.--- � ; 5 days - npr„ns - LARVA ±St - ii _ 2 Crays - ranLhS _ LARVA 4th 3 cayz - npntns �7 LARVA 2ra . 2 aeyllys - nontns ``• LARVA s 0 ' !ceyt wonths - Y,:•�-1�`t�TJrt',� !•3✓t.-.st.:e' y� - :F - � -. 3 Ecology Adult.Ae. sierrensis form mating swarms and seek hosts during daylight hours: In northern California, depending on when rains flood - eggs,Ae. sierrensis overwinters in either the egg, larva, or pupa stage. Eggs flooded before September hatch, larvae complete development, and pupate. Pupal development is arrested during the winter months and adults emerge in the spring. Eggs flooded after �. October hatch and larval development is gradual during the winter months.- Pupation occurs in the asK D4kW spring and adults emerge.' Eggs that are not flooded fill^t activity itq^t activit overwinter. On flooding in the spring these eggs hatch, larvae complete development, pupate and adults emerge. ` D<y rtt:nQ • Diccd feeC:nq Seasonal Cycle-Northern California Flood De'a Jan Feb War Apr May Jun Jul Aug Sep Oct Nov Dec Ewly Fall P P,A P,A A E,A E,A E,A E E L P P We Fall L t_A P,A A E,A E,A E,A E E E L L Spring E I,A P,A A E,A E,A E,A E E E E E _ Adult Ae. sierrensis females feed primarily on E=egg L=larva P=pupa A-adult mammals. In a California study, rabbits, cattle, deer, and humans were the source of blood meals. Mating occurs during the day in male swarms that form Man—el 01.1%) around warm-blooded animals or when a male locates unleenllftC ��.,,, Febb,lt(1e.2) �.XVI. a resting female. Males use terminal c(aspers to attach `t .,yVtP�`,.�4 end to end with the female. Mating takes 30 to 60 i; :=;�:� •, seconds. Females deposit eggs above the water line on the sides of treeholes. Immature stages breed primarily in oak y' tree rot holes, but also in sycamore, cortorlv✓ood, ., maple, buckeye, bay, elderberry, black walnut, Englishr%-%%�. . cat,lt(24.7) walnut, white fir,laurel trees.olive, eucalyptus, willow, and Cal s� y, Larval Habitats <criculture Indust Domestic Nziural . Deer 121-0 bantls• ,rteho:es 1:anng Ireuchs' rock poc!s' cemetery urns' •�- Iir,Cans pain"car** In wooded rural and urban areas, adult female Ae. •occasional sources that contain leaf litter sierrensis can be very pestiferous during spring and summer months. Females will feed on human hosts Adults remain near breeding habitats dispersing only a outdoors during daylight,,dusk, or night hours. few hundred feet. Diseases Vectored Flight range from breeding habitat Virus Protozoan Round worms C=1ty Pax inum Western Equine Encephalitis (Lab) Dog heartwcrm EL,:•,=- California Encephalitis (Lab) 0.0 0.1 0.2 0.3 0.4 0.5 0.5 0.7 0.3 0.9 1.0 Control Measures "e ° t Immature mosquito populations can be reduced by a combination of physical and chemical methods. Mosquito Abatement Districts currently apply a w bacterial protein crystal (Bri), an insect growth regulator (rliethoprene), and a light mineral oil (GB Fec.aIe 0.t 1111) to mosquito breeding sites. Adult populations <, can be reduced with specialized equipment that \; t dispenses aerosol droplets of a plant extract Fcc.ale`�0.1 (pyrethrum). Ken Boyce&Susan Maggy,Sacramento/Yolo Mosquito&Vector Control District "' BIOLOGY - MOO"", V' F` 4 Culiseta i»omata Introduction Morphology Culiseta inornata is a large' mosquito that is abundant Egg: .White when first laid, darkening to a light-brown in California during the cooler months. It is commonly within a fey hours.- Individual._ eggs.are elongate with called the autumn duck club mosquito. one end bluntly rounded and the other pointed. They are_.1.0 mm° long..,, Eggs, are laid.together on, end Classification, forming-'a- boat-shaped raft.that floats on,the. water Phylum Arthropoda (crustaceans,spiders,insects) surface Class Insecta (insects) Order Diptera (files) Family Culicidae (mosquitoes) t Subfamily Culicinae Genera Culiseta Subgenera Culiseta Species inornata Distribution Larva: Cuticle (body wall) is transparent with external sclerotized (hardened) areas a dark brown. Internal In Forth America, Cs. inornata ranges across the organs are visible. Larval instars range in size from 1.5 United States into northwestern Canada: In California, (first stage) to 8.0 mm (fourth stage). The body is it is collected from all 58 counties from sea level to divided into three parts: head, thorax, and abdomen. A 10,000 feet. siphon (air tube) is located on the terminal abdominal segment. Key larval characteristics are (1) long air tube without pecten; (2) air tube with paired hair tufts near base; (3) a strong usually 2-branched lateral hair on anal seglrient vdiich is as long or longer than, saddle; and, (4) dorsal spicules absent from anal saddle. - :-__......"`1�:tee- y=.l._.....___'.v: t_•._. _^_:._.._.' .T:•�6�• —�c nen Life Cycle ri ' �f <- oizx herds As illustrated, Cs. inornata has four distinct life stages: egg, larva, pupa, and adult. Depending on environmental conditions, the life cycle can be Adult: Key adult characteristics are (1) cross veins on completed in 22 to 51 days. wings nearly.in line, (2) abdomen blunt; and, (3) hind - tarsi (leg joints) without bands. ADULT ` Ida y to months • EGGS PUPA 4 to Q days 4-lOdays +e. f:e=—� :-°., r:..:7 �: ,tL';.Ii�' ii '�^ _ #r--• •zr� <t.7,:� LIMA aI:J ' Y�i L.w ..� _ - t..x•lxne' t LAAVA41h 4toadr;�'� JTY}at° fn j 4to9days t'6 LARVA Sid LARVA ¢2 3 to Q day y +. n to O day ,4ats,�t 3-.1�11sda�Y>�fj�Y .�, r .. '.➢r,.a2. Y ^.' i n5t `. ,.�w�: ...uk1' _ - .:. "".,: _esr'•�: r>: : w+ �.. Ecology _ Adult Cs. inornata daily activity is based on light "intetislty�ar i temPe tut�e�Tllight activity is nocturnal, In the interior valleys of California adult female C' but is reduced'w ten temperatures drop below 46o. inornata enter a resting state in the warmest months of the year. During this period egg laying is temporarily arrested and flight activity reduced. Females rest in ground tunnels and animal burrows. In the_fall,_females. TY�,H leave summer resting sites and begin depositing eggs In'- aquatic' habitats • ' The ensuing generations' of females continue to produce'and deposit eggs through DUSK W DAWN the fall and winter.'7n the coldest part of winter females host reeklnp ael�{testing flu temporarily. become inactive.-7 When temperatures warm flight activitxresumes and females remain.active D,,,. - --- until spring. Immature stages (larvae and pupae) appear in early fall reaching the greatest abundance in early fall and spring. Seasonal Cycle-Interior California valleys Adult Cs. inornata females feed primarily on large Mcnth: Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec mammals. In a California study, cattle, horses, and Stage: E E E E E E E E E rabbits were the source of blood meals. L L L L L L L L L P P P P P P P P P AF AF AF AF AF AF AF AF AF AF AF AF r AM AM AM AM AM PA AM AI,A AM AM E=scg L=larva P=pupa AF=adultfemale AM=adult male attic Sold=peak populations Individual males locate newly emerged females and use terminal claspers to attach.end to end with the lemar1 e. - bbi Cs. inornata females lay eggs (oviposit) in a variety of 5 a� natural and domestic aquatic habitats. Immature .. ,g _ stages can breed in either fresh or brackish water. Immature stages cannot tolerate water temperatures above 860. When populations are high adults can disperse from Larval Habitats breeding habitats and become pestiferous in rural and Acricul;ure Indus! Domestic Natural urban areas. Females will feed on human hosts duck Gluts gravel piss containers v.et!ands outdoors during daylight, dusk or night hours. .ice Ields rcadstde diaches ra:•n pools orcha.•ds swimming pools S;n,,cs s";&Gedrains t:es.'nvaterrnarsh Diseases Vectored sap,rrwsh p"holes - s nc+.pools Virus Protozoan Round worms - meadov+s Depending on environmental conditions and host Jamestown Canyon, None None p 9 Western Equine Encephalits (Washington) availability, adults may remain near breeding habitats St.Louis EncePhaliitis(tab) or disperse 4 - 6 miles from these sites. Adults have Cache valley(t}tan Norn Dakota) been collected up to 14 miles from larval breeding , Control Measures habitats. - Flight range from breeding habitat (miles) Immature mosquito populations can be reduced by a combination of physical. and chemical methods. Mosquito Abatement' Districts currently apply a ° 'Z '° bacterial protein crystal (Bt1) - an'`'\insect growth regulator (methoprene) and a light mineral oil (GB Kale {�Ia,ly) .-3 1111) to mosquito breeding sites. / Adult populations can be' reduced._With specialized 1!aie (caxinuc) �` t. : a 4 equipment that dispenses aerosol droplets of a plant r extract(pyrethrum). q ' i Female (tally) 1-3 t Female (.-,axi0um) �'� :.r w,.�},�r-: .r" p;,`"v-.'"�j'f.s...r`i.5,}�.�.t.:s r rWw � �_� N � �,. ', �i��'il-• '.' +�i'^t^�"43d -��� � >_ •�- ' Ken Boyce&'Susan Ma99Y�.Sacramenio/Yolo Mosquito&vector Control District P '' i.,.F '�L�F, '� ° >fy it "'1as.`a.' '.:'.: - ii7• J,.:+Y: � ]. .,� E L -c r ,,.K. M ".,,,�'�`�y"sr�,,ryyyt r �•`'r':.�•••++yy��,..jj-,,..., - .,'r<• {�":`^ � 'y��,rq•}ti�•'. •.$'atn '"�^{""�t�-K`a�3'j�r�.,s 'r!t'� t '.� •. F4<TSi9.. .{�. ... •'�1''y.s� cC�C3t.- _ ... YO.t.. . 'ae!' _ .. 'Otw.. m ._. t�.� Z1 L�-h+•�w4F, z�4X�F+_��.�!+�4. a•5 .. , t Reprinted from MOSQUITO NEWS, Vol. 43, No. 2 June 1983 212 MoSQUrro NEws VOL. 43, No. 2 i 1 MOSQUITO CONTROL AND SALT MARSH MANAGEMENT: FACTORS INFLUENCING THE PRESENCE OFAEDES LARVAE STEVEN S.BALLINGAxn VINCENT H.RESH ' Division of Entomology and Parasitology, l;nivcrsity of California, Berkelev. CA 94720 ABSTRACT.The addition of ditches to increase tidal circulation in salt marshes provides effective mosquito control, but economic and environmental factors require accurate determination of potential mosquito- breeding habitats to maximize the efficiency of this process. Stepwise multiple regressions were used to determine which of several physical and biological.variables were related to the occurrence and abundance of Aedes dorsalis and Ae. squatniger larvae that were dip-sampled monthly front 44 ponds in eight San Francisco Bay,CA,salt marshes from August 1981 through June 1982. Most of the variance in the dependent variables (45% of occurrence and 229c of abundance) was accounted for by pond inundation height,i.e. the minimum 1 tidal height required to flood a marsh pond: additional—variance was accowue or pond area (5 of occurrence and 49 of abundance), abundance of the water boatman Trichocorixa reliculata (12 K of occur- rence),and percent cover of emergent vegetation (6c/c of abundance). Based on these physical and biological characteristics,a flowchart of decision rules can be used to determine whether a given marsh pond should be ditched. INTRODUCTION shorebird composition and patterns of use are Ditching has been a successful mosquito con- altered (Burger et al. 1977). trol technique in salt marsh management since To minimize the impact of ditching on the turn of this century (Smith 1904, Headlee aquatic habitats, it is important to restrict 1936, Ferrigno et al. 1975). Recentiv,the use of ditching to only those ponds that produce sig- ditches has increased because they provide an nificant numbers of mosquitoes. Ferrigno et al. inexpensive alternative to insecticides (Telford (1975) suggest that this is best done by moni- _ and Rucker 1973, Provost 1977, Shisler et al. tori�potential mosquito-breeding sites and 1979, Resh and Balling 1979, De Bord et al. c itching otT lose t iat pro( uce mosquitoes. U {. 1975). By connecting mosquito-breeding ponds Un fort unateh•, the number of potential sites a to nattira t a c anne s itches alter the hv- often makes monitoring prohibitively expen drolo ical characteristics of the nds i a live. For example,if a monitoring program was manner t at a nntnates ill a duction. undertaken in the 1,145 ha Petaluma Marsh in In 'an -rancisco Bay salt marshes,ditches have northern San Francisco Bay (Fig. 1), over J no adverse impact on many terrestrial compo- • 15,000 ponds and potholes would require reg- J nests of the marsh,such as arthropod commu- ular sampling and evaluation. nity diversity(Balling and Resh 1982), the den- Mosquito control efforts in San Francisco Bay sity of some arthropod populations (Barnby salt marshes have been directed toward two and Resh 1980),or plant composition and pro- species,Aedes dorsalis(Meigen)andAe. iquatniger duction (Balling and Resh 1983a),but they sie- (Coquillett). The multivoltine .qr. dorsalis nificantly lower the invertebrate f emerges from tidal sat mars es along t e v marsh poems( _esh and Balling 1983). In ad-I Ca ifornia coast from anu r di—t on, Atlantic coast studies have shown that (Te ord 1958). Coastal populations occur al- when larger ponds are ditched, waterfowl and• most exclusively in wa salit a ter, whereas inland .���.�A -� Jt NE, 1983 MOSQrrro NEws 213 MATERIALS AND METHODS fer�L�"• Forty-four unditched sites in eight marshes (Fig. 1) around the San Francisco Bay Area N sc•ere chosen to provide a broad range of values for each selected environmental variable that Might influence the distribution of Ae. dorsalis and Ae. .squamiger. Two types of breeding habitat were included in the study: ponds, which are formed in zones of saturated groundwater, and potholes, which are formed from the blockage of first-order tidal channels. :Although differences in the origins of these habitats result in some differences in their t physical characteristics,for the purposes of this 1 GOLDEN paper and for mosquito control, both habitat �•*� types can be considered the same and will be SAN referred to as ponds. f RANCISC0 "oeeRrJ L."°�"s Several static(i.e.unchanging)variables were BAY °""Jor L."°,"S measured for each pond: pond inundation height (the minimum tidal height above mean L I��! JLovi" lower low water(MLLNN) necessary to inunclate the pond, Balling and Resh 1983b), basin area, maximum depth, and percentage cover of OCEAN emergent vegetation. 'These variables were OCEAN measured after the highest spring tides of June 1982, when each of the pond basins was filled. Several dynamic (i.e. changing) variables di- Fig. Map of the San Francisco Bay area te were also measured: pond soil salinity, pond Golden (:arc reference station.uing locations the eight studs' marshes and the water salinity, and relative abundance of both er mosquito larvae and the numerically domi- nant pond invertebrate, the water boat- populations occur primarily in fresh water man Trichocorixa reliculata Guerin-Meneyille (Bohart and Washino 1978).:Fhe uniyoltineAe. (Hemiptera: Corixidae). Pond soil salinities, it - sq.1 m)m er is restricted entirek to sat marshes cluded because of their possible influence on (Bohr man( as imo l9) 8),anTis paructTly oyioosmon (e.g. Petersen and Rees 1966), were ccmimon m diked kes mars i in( s t Gat are su ject to measured from 5:1 (by dry weight) distilled- , wnuer (loodmg. water dilutions of oven-dried(70DC),6-cm deep in Pacific coast tidal marshes,Aerles produc- soil cores. Although soil salinities vary through Lion is limited to areas that are inundated onl- the vcar, we measured them only in late Ocio- by spring tides (Telfor(i 1958, Provost 1977). ber, when drv-season accumulation of salts in However, no study has yet quantified the envi- the pond basin ss•as greatest, soil salinity dif- ronmental factors that determine Ae. dor3alis ferences between ponds syere maximized, and and Ae, squcnrriger occurrence within this tidal the greatest number of ponds trere completely region. Studies of other Aedes species indicate dry. Pond water salinity and abundances of that.factors such as flooding-desiccation cycles mosquito larvae and T. reticulata were measured (Connell 1940), soil moisture (Strickman 4 to 7 days after the highest spring tides of each 1980a), soil salinity (Chapman 1960, Knight month from August 1981 through June 1982 1965, Petersen and Rees 1966, Strickman (11 sampling dates). Mosquito and T. reliculata 1980b), vegetation type (Frohne 1953), and populations were sampled with a 355 till dip- predation pressure (Frohne 1953, Rees 1958) per: 10 to 40 clips %,:ere taken per site, de- can all influence distribution.This paper quan- pending on larval density and pond area. iiiatiyel• describes the larval habuats o e. r or- -ro determine which set of independent yari- .sa 13 and Ae. s urnrrigrr in San Francisco Bay salt ables was the best predictor of mosquito pro- marshes• and uses t its information for deyel- duction, stepwise multiple regressions (Zar opuig simple cnsion rut es 1cn drter����„in9 1974) were run using two_dependent variables: whet er specific ponds should be ditched. prclornon o7 swung dates— on%Vl1IC i larvae When used in a salt marsh management pro- occurre( occurrence), and larval abundance gram, this approach can reduce both the cost averaged over all sampling dates (abundance). and the environmental impact of ditching for Since c tic mg is considered necessary when mosquito control. eiiher.4e.dorsudis orAe..squmniger is present, the 214 MosQUITo Nt•:ws Vot.. 43, No. 2 occurrence and abundance values were derived ponds was most highly correlated with pond from combined counts for both species. Pre- inunc anon heig 45%r ofthe variance m arva dictor variables tested were area,depth,height, occurrence was accounted for by this factor. percent cover of emergent vegetation, soil sa- Mean relative abundance of 7'. reticulala and linity, water salinity, and T. reliculata abun- pone)area accounted for an additional 12%and I Glance;the last two variables were averaged over 57c of the variance, respectively. Addition of all sampling date. the other four variables (soil and water salinity, percentage cover,and pond depth)contributed RESULTS less than 27c of the remaining variance.There- fore, the optimal regression equation using 1 Aedes larvae were collected in 22 of the 44 standardized partial regression coefficients was: ponds sampled. 'fhe two species showed a dis- tinct temporal partitioning:Ae.darsalis occurred Occurrence li (1.71 pond height from March through October with peak abun- —0.31 %. reticulcrla abundance (1) dance in August, whereas Ae. .squamiger oc- —0.25 pond area. curred from November through April with peak abundance in January; substantial larval The abundanc of Aedes larvae was als co-occurrence of the two species was restricted hi h come a e< syu> ion tnun anon height: I �— 6 to 'March. These patterns closely match those 22�ot t re variance was accounted or this reported by Telford (1958) in a northern factor. Percentage cover of emergent yegeta- California coastal marsh.The larvae showed no tion accounted for an additional 6% of the re- spatial differences since both species occupied maiming variance,and pond area accounted for the same ponds, even during the period of 4%. The addition of all other variables contrib- overlap. uted less than 29cc. Therefore, the optimal re- Culiseta inor•nata (Williston)was the only other gression equation was: species of mosquito collected in the 44 ponds Abundance = 0.46 pond height examined. Although Bohart and Washino +0.22 percentage (2) (1978) reported that Cs. inornata is an autumn- cover — 0.21 pond area. winter-spring species in California,we collected it only during March and April,as (lid Telford DISCUSSION' (1958). a restriction o this species to earh spring in salt marshes may result from a limits- The- retrressjon analv.,;es indicate that tithe tion in salinitv tolerance, since arvae were nosi im ortant orrelate of both occurrences j ound only in water wi sa inities up to 15 0/oo, and a ttnG and of Aec es arvae to e_44 salt J a level that is—exceeded y most p0 on s rom marsh ponds examine is rond inundation ay t roue ecem er. n contrast, e. orsaW r� t n ac c loon, t ere is a mrtunmm-Trergrit and Ae.squamiger were found in water salinities w which mosquito production ceases (Fig. ] from 2 to 61 o/oo and 2 to 52 o/oo,respectively. 2). This height, which we will refer to as the ITrichocorixa reliculala was collected on every mosquito production threshold, is a_pprox- sampling date in 17 ponds,and at least once in imately 1 Fi2 cm above MLLW for San Francisco all 44 ponds. Characteristically, the ponds in Bay marshes. Approximatefv 38% of all high which we consistently collected T. reliculala re- tic e`f s exceed this height through the year. The tained water throughout the year because they overlap of mosquito-producing and non- were low enough in height to be flooded often, producing ponds(from 162 to 172 cm,Fig.2)is or large enough in volume to withstand long a product of the broad regional coverage of our I periods without inundation.Combined samples study; this overlap is removed when data from of nymphs and adults,averaged over all ponds, any one marsh are considered. 'fhe value of showed that T. reliculala reached peak densities 162 cm for the mosquito production threshold in August and September,decreased rapidly in is also specific to the tidal range (\IHHW — i October, and then remained low until late NIHW = 174 cm at the Golden Gate reference IApril. station) of our study sites in the San Francisco Although fish are abundant in the tidal Bay. For regions with different tidal ranges,we channels and ditches of San Francisco Bay would estimate that the mosquito production marshes (Balling et al. 1980), they are seldom threshold would be halfway between NiH1N observed in the smaller, unditched ponds(Bai- ling 1982).* Apparently, their access is re- k stricted by the thick growth of piekleweed Balling. S. S. 1982. i'he influence of mosquito c'omrol recirc'ulati6ii ditches on aspects of San Fran- I� (Salicornia virginica L.) that surrounds most of disco Bas salt ntat•sh ar,hropod communiiies. Unpub- the pond h fished I'It-[). Dissertation. University of California, �:jThe occurrence of Aedes larvae in different Berkeley. 292 pp. i •JUNE, 1983 Nlosqurro MEWS 215 I MOSQUITO PRODUCTION I O THRESHOLD I • o I I � I • • w 0,8 t U I Z 1 •o LU � I , X 0.6 I • Z I V I U 1 0 1• • 00 0.4 I • •• W I • C I • <10om2 W I • p � > 100 m2, < 30% cover Q 0.2 o >100 m2, > 30% cover to 0 I o I I 0 •• • 00000 «�iw • 600o 000 i 130 140 150 160 170 180 190 200 MHW MHHW ' POND INUNDATION HEIGHT (CM above MLLW) Fig. 2. Comparison between larval Aedes occurrence (as a proportion of all sampling dates) and pond inundation height for 44 ponds in eight San Francisco Bay Area salt marshes. (mean high water) and 14HHVV (mean higher noted separately in Fig. 2 (open triangles), and high water) (Fig. 2). although the inundation heights of these six The determination of pond height to de- ponds indicate that they should produce coos- lineate whic pon s are mosquito fiaMtats i quitoes, larvae were collected in only one of a parently unnecessary in , t antic coast them.In contrast,larvae tvere collected in 5 of 7 I�l mars ies cause o t e ,.•ell-defined and con- ponds that were greater than 100 m2 and had /V sistent patterns o yena zonation found greater Ihan 307, cover (Fig. ' , open sire es); t eeLe. Lones containing Sparlina patens (Aiten) the two non-pl•o tieing pone s syere )elow the Muhl. or a mixture ofS.patens and short-form mosquito production threshold. Apparently, Sparliva alleruij7ora Loisel. are indicative of it-- large ponds that grade into the surrounding regularly flooded mosquito-producing areas vegetation often have margins that become suf- (Ferrigno et al. 1975, Provost 1977; NV. M. ficientl dry for Aedes oviposition.Once refilled, Meredith,personal communication);such areas such pond margins are also protected from can be reliably identified and subsequently wind-generated waves that interfere with the ditched. in contrast, vegetational zones in the respiration of surface-breathing mosquito lar- salt marshes at•outu . an Francisco w are vae.The importance of emergent vegetation as '` I characterize v exteos a areas.of pyerlan cover for ntos Intolarvae is f d cause he ! �tero eneo Influences o. by the significant, positive relationship between freshwater inflow it this estuary(Atwater percentage cover and mosquito abundance in j et al. 1979). regression equation (2). Pond area is negatively correlated with coos- Abundance of Trichocorixa reliculaln was in- � ) qulto pro uctton tit the regression a uatiom, ycrsely related to mosquito occurrence but not aGhough the significance of this relationship is to mosquito -abundance. .Although many diminished when the cover of emergent vege- corixids are known to be predators (Jansson tation increases. Six ponds greater than 100 nI= and Scudder 1972),and at least one species has in surface area and with less than 30`7 cover are been credited will' reducing mosquito popula- 1 216 Mosgt•rro Ntws VOL. 43, No. 2 1 bons (Sailer and Lienk 1954), 'T. reliculala is tion frequencies to create suitable habitat for primarily a bottom feeder that rarely takes salt marsh mosquitoes. mosquito larvae as prey. In fact, the observed inverse correlation is not a pre ator•prev re- MANAGEMEN"C APPLICATIONS lationsh-D. butthe result of contrasting - habitat requirements. Aedes dorsalis an e. A judicious approach to ditching in salt uar sqnirer have rou ht-resistant eggs, which marsh management programs requires an ac allow them to exploit temporary onds, curate determination of mosquito-breeding Iwle rnx_T +•.,�i.•+,lnln hae nn r�t'oneht-resistant habitat. When practical, potential sites should "life stage and is generally restricted to erma- be monitored o�t"re presence ol-mos uito lar- n ent ponds (Balling 1982).* It follows, there- vae, since monitoring will give the most defin- fore, that the absence of T. reliculala from a rove information regar mg which ponds pond, or the presence of mostly recolonizing should be ditched. Such monitoring programs LGCR�a adults, would indicate that the pond has re- should rcti-fish a tolerance level of mosquito ` 1 cently dried up and is likely to be a mosquito- abundance ab rich control measures breeding site. should be undertaken, because in some cases 1 Although pond depth is significantly corre- the discovery of a single mosquito larva has lated with mosquito occurrence (r = 0.47, p = been sufficient justification to ditch a pond,de- 0.001) and abundance (r = 0.34, p = 0.023), it spite the possibility that this larva may have was not an important factor in either equation been passively transported into a non- (1) or(2). Rather than reflecting any biological producing pond by inundating tides. In addi- relationship, the significant correlation of tion, the temporal patchiness of larval istc tribu- depth with mosquito production is presumably ttons s,tiggests t at at east one year o re ular due to its correlation with pond inundation sampling ,,Qui( )e necessary to identify all height (r = 0.68, p = <0.001), a relationship potenna ree mg sues In a mars urng our also described by Lesser et al.(1977).Pond depth study, no singe samp Ting date could be used to is undoubtedly important to mosquito produc- accurately predict which ponds would produce tion when ponds are so shallow that they dry mosquitoes; of the 22 ponds that produced up before adults emerge,but our samples were mosquitoes sometime during the year,less than ' taken too early (4-7 days after inundation) in half contained larvae on any sin the desiccation cycle to detect whether such a he use o environmental correlates to pre- relationship existed in the ponds-w� xamined. diet mosquito distribution is a, accurate, cost- Pond water salinity_ ,.•:unrelated to mos- effective all -native to monitorin larval po u- quito occurrence or a un ante.an t is agrees lations. . s predictive +aria es, t ese corre ates v,uh the cone usums o—fC.onne ( 4 )and Tel- are pest considered in a simple flowchart (Fig. ford (1958). Petersen and Rees (1966) sug- 3). The flowchart indicates that in San Fran- gestec�T tithe impact of salinity on Aeries disu•i- Cisco Bay salt Marshes, a Pon „•i prouce ' bution more likely influences the selection of mosquitoes if it is above t e mosquito pro(uc- oyiposition sites by females than the survival of Lion threshold ( i cm,adjusted to t ie .o en the salt-tolerant larvae. However, our mea- Gate reference station),and it it is less than 100 surelnents of dry-pond soil salinities showed no m2 in area. If" it is above the t res o an relationship to mosquito occurrence or abun- greater t ian 100 m2, the pop v,i pro uce dance. Possibly, the threshold relationship that mosquitoes on y i more t an /c o tie asin Petersen and Rees (1966) found for Aedes contains emergent vegetation,i.e.i t ere is suf- oviposition is subordinate to tidal inundation in ficient cover. ones a ow the threshold or salt marsh habitats. ponds greater than 100 m' with yell-defined Mosquito-producing ponds located in salt banks will not produce mosquitoes, and should marshes other than the Petaluma Marsh (which not be ditched. is one of the highest marshes in the San Fran- When we used these criteria to classify which ' disco Bay Area) were primarily associated with of our s ud-v ny�?T5Tw1tIiL7zs. ix 1 areas altered by human activities. For exam- ponTihaI did not prod nosq were pie, dikes („'Lich are used to convert tidal classidas"ditches a 146/44) error e. A marsh to salt cv,iporaiion ponds, pasture land, changein i}ie critical +values o any of the pre- , ' farmland, and waterfowl habitat) can affect dicior variables results in a change in the com- neighboring tidal inarshcs by restricting tidal position of these errors. For example, if the flow and artificially raising pond inundatiot. mosquito production threshold is shifted up- heights. This occurs when the weight of the ward to the point halfway between MHW and dike displaces and clevaies the semifluid marsh. MHH\N, three ponds that produced mos- Both changes may stiff iciently reduce inundla- quitoes would be classified as"do not ditch"and JUNE, 1983 MosQtliTo NEWS 217 S THE POND HCIOHT GRC AT[R THAN THE NOSOUITO PRODUCTION THRESHOLO? NO ` YES ' IS THE►ONO AREA LESS THAN 100 Nt NO YES IS THE PERCENT COVCR GREATER THAN 30 t? NO YES NV IV DO NOT DITCH DITCH Fig. 3. Flowchart of decision rules for determining whether a'pond in a San Francisco Bay salt marsh should be ditched for mosquito control. The mosquito production threshold is the pond inundation height below which mosquito larvae do not occur. ' three ponds that did not produce mosquitoes ponds that are naturally below this threshold,l would be classified as"ditch,"a 14% error rate. frequent u 1 Tiiund--anon keeps t e su s If the mosquito production threshold is shifted sufficient} wet either to iscourage oviposition— ' upward to 172 cm to guarantee that no non- or to prevent proper condifi—oning of the eggs. producing ponds are ditched, then ten There ore, to e e ecttve, uc es nee not e mosquito-producing ponds would be classified dug deeper than the depth req� uirecTto over as"do not ditch;'a 23% error rate. Error rates the poihd iriu'n<laiion lei lit below the mos uito ' can, of course, be lowered by confining the piMUffton threshold. Because tidal restrictions analysis to a single marsh and eliminating the onoiposition are undoubtedly present in all heterogeneity due to combining several salt marsh species ofAedes, a management ap- it marshes as aye did in this stud.•. In contrast to proach based on the determination of a mos- management decisions based on environmental quito production threshold has widespread ap- correlates, a decision to ditch all 44 ponds as a plication in the control of salt marsh mos- precaution against any mosquito production quitoes. � would result in 22• •%' , ponds being needlessly ditched, a 50% error rate. Decisions to UGC 1maximize mosquito control or minunize enyi- ACKNOWLEDGMENTS — ronnhenta mhpact can a uses to choose critical .-__ wa ues or the Dredictor yarm es. We thank the San Francisco Bay National 1 . Ditching is a successful rnet.E5a of mosquito Wildlife Refuge Complex, U.S. Fish and �" ,✓� control ecaus here is an inun anon Wildlife Service, for permission to include sev- thres o d below w i`c Ifi nosquito pro ucuon eral of the Refuge marshes in our study, the does ii occu . lihough—ditciieT�ffo pro'�;ide C.N1VCA Coastal Region Mosquito Abatement increased access for fish that can prey upon Districts for their assistance on this project,and mosquito larvae (Balling et al. 1980), ditching William H. Meredith, Charles H. Dill, Joshua probably succeeds as a control measure because N. Collins,and Eric P. McElravy for their corn- it effectively lowers the pond inundation height ments on the manuscript.Support for this proj- to below the height that serves as the mosquito ect was provided by the University of California production threshold. As probably occurs in Mosquito Research Funds. r 218 Mosou ro NL%vs VOL. 43, No. 2 iLileralure Cited Headlee,T.J. 1936. Mosquito control facts taught by the passing years.Proc. NJ. Mosq. Exterm.Assoc. Atwater, B. F..S. G. Conard,J. N. Dow•den, C. W. 23:205-209. Hedel, R. L. ,MacDonald and 1V. Savage. 1979. Jansson,A.and G.G.E.Scudder. 1972.Corixidae aw, History,langornts,and vegetation of the estuary's predators: rearing on frozen brine shrimp.J. En- tidal marshes.pp.34 7-385.1n T.J.Conomos(ed.), tomol, Soc. B.C. 69:44-45. San Francisco Bay: the urbanized estuary. Pacific Knight,K.L. 1965.Some physical and chemical char- Division,Am. Assoc.Advance.Sci.,San Francisco, acteristics of coastal soils underlying mosquito CA. 493 pp. breeding areas. Mosq. News 25:154-159. Bailing,S.S.and V. H. Resh. 1982.Arthropod Coln- Lesser, F. H., W.J. Crans and J. K. Shisler. 1977. munity response to mosquito control recirculation Methods to document mosquito breeding on tidal ditches in San Francisco Bay salt marshes.Environ. marshes by artificial means. Proc. NJ. Mosq. Ex- Entomol. 11:801-808. teen. Assoc. 64:162-164. Balling,S.S.and V.H.Resh. 1983a.'I'he influence of_g Petersen,J.J.and D. M.Rees. 1966.Selective ovipo- mosquito control recirculation ditches on plant sitiun response of Ardes dorsalis and Aedes nig- biomass, production, and composition in two San ro,nandis to soil salinity. Mosq. News 26:168-174. Francisco Bay salt marshes. Estuar. Coastal Shelf Provost, M. W. 1977.Source reduction in salt-marsh _*Sci. 16:151-161. mosquito control: past and future. Mosq. News alling,S.S. and V. H. Resh. 1983b. A method for 37:689-698. determining pond inundation height for use in salt Rees,B. 1958.Attributes of the mosquitolish in rela- marsh mosquito control. Mosq. News 43:239-240. Lion to mosquito control. Proc.Calif. Mosq. Contr. Balling,S. S., T.Stoehr and V. H. Resh. 1980. The Assoc. 26:71-75. effects of mosquito control recirculation ditches on Resh,V. H.and S.S.Balling. 1979.Ecological impact the fish community of a San Francisco Bay salt of mosquito control recirculation ditches on San marsh. Cal. Fish Game 66:25-34. Francisco Bay marshlands: preliminary consid- Barttby, M.A.and V. H.Resh. 1980. Distribution of crations and experimental design. Proc. Calif. arthropod populations in relation to mosquito Mosq. Vector Cont. Assoc. 47:72-78. control recirculation ditches and natural channels Resh, V. H. and S. S. Balling. 1983. Tidal circula- in the Petaluma salt marsh of San Francisco Bay. Lion alteration for salt marsh mosquito control. Proc. Calif. Mosq. Vector Contr. Assoc. 48:100- Enciron. Manage. 7:79-84. ' 102. Sailer, R. 1. and S. Lienk. 1954. Insect predators of Bohart, R. M.and R. K. Washino. 1978. Mosquitoes mosquito larvae and pupae in Alaska. Mosq. News of California.Univ.of Calif.,Div.of Agric.Sci.,No. 14:14-16. 4084. Berkeley, CA. 153 pp. Shisler,J. K.. F. Lesser and T. Candeletti. 1979. An Burger,J..J. K. Shisler and F. Lesser. 1977. The approach to the evaluation of temporary versus effects of marsh management practices, particu- permanent measures in salt marsh mosquito con lark• ditching, on nesting birds. Proc. NJ. Mosq. trol operations. Mosq. News 39:7 76-780. Externs. Assoc. 64:184-195. Smith,J. B. 1904. 'The common mosquitoes of New Chapman. H.C. 1960.Observations on Aedes melani- Jersey. N.J. Agric. Ex. Sta. Bull. 171. 40 pp. on and Aedes dormlis in Nevada. Ann. Entomol. Strickman, D. 1980a. Stimuli affecting selection of Soc. Am. 53:706-708. oyiposition sites by Aedes Texans (Diptera: Connell, W. A. 1940. Tidal inundation as a factor Culicidae): moisture. Mosq. News 40:236-245. limiting the distribution of Ardes spp.on a Delawarc Strickman, D, 1980b. Stimuli affecting selection of salt tnarh. Proc. N.J. Mosq. Exterm. Assoc. oyiposition sites by Aedes Texans (Diptera: 27:166-177. DeBord, D. V..G.A.Carlson and R.C.Axtell. 1975. 40:413-41 conditioning of the soil. Mosq. \cos 714 Demand for and cost of coastal salt marsh mosquito 40:4 I3-A. 17. abatement.N.C.Agric.Ex.Sta."Tech.Bull.no.232. Telford,A. D.California.The pasture hiss ry central and 85 pp. northern lifur Seasonal history. .Ann. En- Ferrigno, F., P.Slayin and D. M.Jobhins. 1975.Salt tunwl. Soc. Am. 51:3611 365. marsh water management for mosquito control. Telford, A. D. and J. D. Rucker. 1973. Successful Proc. NJ. Mosq. Exterm. Assoc. 62:3(-38. source reduction on tidal salt marshes. Proc.Calif. Frohne, W. 1953. Mosquito breeding in Alaskan salt Mosq. Vector Cunt•. Assoc. 41:100. � / 1 marshes, with special reference to.4edes punctodes Zar,J. H. 1974. Biustatistical analysis. Prentice-Hall, ~ Dear. Mosq. News 13:9C> 103. Inc., Englewood Cliffs, N.J. 620 pp. r Reprinted fi•an ENVIRONMENTAL ENTOMOLOGY, VOL. 11,No. 4, AUGUST 19S2 Arthropod Community Response to Mosquito Control Recirculation Ditches in San Francisco Bay Salt Marshes' STEVEN S. BALLING AND VINCENT H. RESH Division of Entomology and Parasitology.University of California,Berkeley,California 44720 i ABST ' F.nviron.En ol. 11:801-808(1982) The impact of mosquito control rec• ulation ditches on Paci is Coast salt marsh ecology is largely unknown.This study compar the arthropod community tructure near mosquito control I ditches and a natural channel wi that in the open marsh.Bi�v ekl�D-Vac samples,in two San Francisco Bayma_she were aken November 1977 to 1978 In the pickleW eed-dominated Petaluma Marsh,arthropod Iversity in the dry season ryas huh r near mot 1�the difcht anndnaiu- ral c anseTthan,in_the_0 en maisfi.-TFiis corresponded to g adients ofincreaslog water iab!e 1 Fieigiii,groundwater sali ity, and soil surface salinity. Cony sely, in the wet season, diversity was lower near the two newest ditches than the open /ahwhereas diversity near the natural channel and the oldest ditch was similar to the open mhese differences are best explained by higher plant structural diversity near the natural chahich offers refuge from high winter tides. There was no significant difference in arthropoass near a ditch and in the open marsh. In the floristically diverse Suisun Marsh, thereno significant differences between ditched,natural channel, and open marsh arthropodties during either season. Results suggest an eventual convergence of arthropod commructure along ditches and natural channels. IMosquito control recirculation ditches, used in th arthropod community near—.a ditch different North American salt marshes since the early 1900s, fr m that in`the open mars�?.Second�,.--iT—the ar- t are intended to drain pools and low areas on the t i:opod community near a ditch different_from that marsh surface that serve as mosquito breeding sites. ear a natural channel? The first question examines They have been designed either to directly connect fie effecfs of-d12ch construction on arthropod com- specific pools to natural channels or,in more porous munities in areas previously undissected by water- soils,to indirectly drainr)ools by a g`3dedsystem of courses. The second question examines the similar- deeper ditches which intentionally lower the marsh ity of diversity patterns perpendicular to ditched water table. In the 1940s, this latter approa`ch eli sites to those perpendicular to a natural channel site. cited particularly serious objections from wildlif The study is part of a project designed to evaluate f biologists who offered evidence that lowering t e the impact of recirculation ditches on the salt marsh water table adversely affected marsh vegetat' n ecosystem (Resh and Balling 1979, Balling et al. and, indirectly,waterfowl and mammal populati ns 1980). (Provost 1977). ' Concern over ditching impact diminished bet een Materials and Methods World War II and the late 1960s,when extensi% use Site Description of organic insecticides to control salt marsh mos- The primary study area was the Petaluma Marsh, quitoes precluded further need for ditching. How- ever, recent recognition of the value of oastal Sonoma County,Calif. (Fig. 1),a 1.145-ha mars to ' marshlands to estuarine and adjacent marine aters the Petaluma River basin, 10 km north of S ablo coupled with concern over excessive insectic de use Bay. The plant community is dominate y a single has renewed interest in ditching as an alte native species, pickleweed, Salicornia vi nica L- From mosquito control measure (Provost 1977). I areas 1969 to 1976,' mosquito abate nt ersonlle.Lc-o�where a large percentage of marshland ha been necte mosquito-breed_i_n ols to natural channels filled or diked,such as the San Francisco Bay,prop- wit h31tc dug by a to all_terrain vehicle(Fig. er management of the remaining pristine mars es is 2). of considerable interest and importance. The secon tudy area was a tidal portion of ' Although recent ditching studies have cone - Suisu rsh, Solano County, Calif., a 500-ha trated on specific arthropod populations (Lesser et rs located between Cutoff and Suisun Sloughs,6 al. 1976,Shisler and Jobbins 1977,Barnby and Resh km north of Grizzly Bay. This marsh is flooded less 1980),the response of the arthropod community as- frequently by less saline waters and is more floristi- ' sociated with marsh vegetation has not been tally diverse (dominated by Distichlis spicata (L.), examined. The present study was designed to S. virginica,Juncus balticus Willdenow,and Jaumea analyze the effect of ditches on the arthropod tom- carnosa (Lensing)] than Petaluma marsh. The de- munity structure of representative San Francisco Pressions and shallow pools in this marsh were con- ' Bay marshes. It focused on two questions. First, is netted to natural channels by hand-dug ditches in ,-� 1933. 'Received for publication 8 June 1981. . 801 ©1982 Entomological Society of America 0022-0493/82/0408-0108$02.00/0 Reprhaed flop': ENyl:.o MENTAL Er<TC%IOLOGY, VOL. 1 1, No. 4, AUGUST 1982 - Arthropod Community Response to Mosquito Control Recirculation Ditches in San Francisco Bay Salt Marshes' STEVEN S. BALLING AND VIINCENT H_ RESH Division of Eniomolo;y and Parasitc[ocv.University of California,Berkeley,California 94720 ABSTRACT Environ.Entomol. 11:$01-808(1982) The impact of mosquito control recirculation diic:•,es on Pacific Coast salt marsh ecology is largely unknown.This sandy compares the arthropod community structure near mosquito control ditches and a natural channel with that in the open marsh. Biweek1w D-Vac samrJes_in two San Francisco Bay mar,_; mere taken_November 1977 to 1978. in the pickleweed-dominated Petaluma Marsh,arthropod diversity in she dry season u-as higher ne-1r UotTFtthe di:chZe-an natu- ril c a- nTi nea than in the coen marsh.-Tnis corresporded to gradlecas of increasir:g water table 6eis2,h,groundwater salinity, and soil surface salinity- Conversely. in the wet season, diversity was lower near the two newest ditches than the open-marsh,whereas diversity near the natural channel and the oldest ditch was similar to the open marsh.These differences are best explained by higher plant structuraf diversity near:he natural channel which offers refuge frc-n high winter tides. There was no siE.trficant difference in arthropod biomass near a ditch and in the open marsh. In the floristicalid diverse Suisun 'Marsh, there were no significant differences between ditched, natural channel. and open marsh arthropod diversities during either season. Results suggest an eventual convergence of arhropod commz_,nity structure along ditches and natural channels. Mosquito control recirculation ditches, used in the arthropod community -)ear-.a ditch different North American salt marshes since the early ii900s, from that in-t e--open mars Second.%s the ar- are intended to drain pools and low areas en the thrC'p-od community near a loch differe_nt_from that marsh surface that serve as mosquito breeding sites. near a natural channel? The first question examines They have been designed either to directly connect tfie effecfi of dFcl coristruct-on on arthropod com- speciftc pools to natural channels or,in more porous mur.ities in areas previously undissected by water- soils,to indirectly drain pools by a ggded sys:em of couaes. The second question examines the similar- deeper ditches which intentionally lower the -narsh ity of diversity patterns pe-pendicular to ditched 'A er table. In the 1940s, this latter approach eli- sites to those perpendicular to a natural channel site. cited particularly serious objections from wildlife The study is pars of a project designed to evaluate biologists who offered evidence that lowering the the impact of recirculation di-ches on the salt marsh water table adversely affected marsh vege-ation ecosystem (Resh and Balling 1979. Balling et at. and, indirectly, waterfowl and mammal populations 19K). (Provost 1977). Concern over ditching impact diminished between Materials and Methods Nk'orld War II and the late 1960s.when extensi\a use Site Description of organic insecticides to contrc4 salt marsh mos quitoes precluded further need for ditching. How- The primary study area was the Petaluma Marsh, ever, recent recognition of the value of�coastal Sonoma County. Calif. (Fig. 2)1 a 1.145-ha marsh in marshlands to estuarine and adjacent marine waters the r etaIuma River basin 10 km. north_of San Pablo coupled with concern over excessive insecticide use Bav- The plant community is dominated by a single has renewed interest in ditching as an alternative species, pickle"eed, Salicoraia virginica L. From mosquito control measure (Provost 1977). In areas 1969 to 1976, mosquito abatement persenneLeoj1- where a large percentage of marshland has been netted mosquito-breeding pools to natural channels filled or diked,such as the San Francisco Bay.prop- "•1tTt ditches dug ity a Spryte all terrain vehicle(Fig. er management of the remaining pristine marshes is 2)• of considerable interest and importance. The second study area was a tidal portion of Although recent ditching studies have concen- Suisun Marsh, Solano County, Calif., a 500-ha trated on specific arthropod populations (Lesser et marsh located between Cutoff and Suisun Sloughs,6 al. 1976, Shisler and Jobbins 1977.Barnby and Resh km north of Griz-zly Bay. This marsh is flooded less 1980), the response of the arthropod community as- frequently by less saline waters and is more floristi- sociated with marsh vegetation has not been call- diverse [dominated by Distichlis spicara (L.), examined. The present study was designed to S. ti:ginica,Juncos balticus«'illdenow,and Jaumea analyze the effect of ditches on the arthropod com- carnosa (Lensing)] than Petaluma marsh. The de- munity structure of representative San Francisco pres_.ions and shallow pools in this marsh %vere con- Bay marshes. It focused on two questions. First, is netted to natur2J channels by hand-dug ditches in --�---- 193;. _'Reccned for publication 8 June 1981. 0 801 C)1982 Entomological Societ}'of America 0022-0493,12/0408-0108S02.00/0 t S02 ENVIRONMENTAL ENTOMOLOGY Vol. 11, no. 4 " cr+,w�,yarn Swh Mneh 1�m 1 Son a Froncisco Boy Petolumo Marsh som 0 2.,­Id odcn"' ray FIG. 1.—Map of the three primary sites and strata sampled in Petaluma Marsh,Sonoma County,Calif.,at the northern tip of San Francisco Bay, Calif. Arthropod Community Analysis slouch. The ditches were similar in width and depth- Sampling Design.—At the time this stud), began to those in Petaluma, but spoil lines were more ir- (autumn 1977), the Petaluma Marsh ditches ranged regular in height, ranging from 1 to 15 cm. in age from 1 to 8 years;sites were selected adjacent To determine the spatial extent to which a water- to ditches constructed in 1975 (site P2, 2 years old), course miP t s-i ificantlyinfluence marsh ar- 1972 (site P5,5 years old),and 1969(site P8,8 years thropods, we sampled the fauna at three different old), as well as adjacent to a natural channel (site distances.or strata,fromeac_h ditch or natural :I: an- PNC). Sites P2, P5, and PNC were located within nei ustd i )­Ethey site tFg. . o strata was 50 m 150 m of each other,with the ditch at site P5 actually long and parallel to the watercourse. Stratum 1 was connected to the channel at site PNC (Fig. 1). Site located between the watercourse and the berm or P8 was located 4 km north,where ditch construction spoil line (within 1 m distance); stratum 2 was just first began, in an area that differs hydrologically outside the berm or spoil line (3 m distance); and J from the other sites. The ditches were 45 cm wide, stratum 3 was in the open marsh (10 m distance). 60 cm deep,and flanked on both sides by a spoil line Water table observations indicated that drawdovm, 6 to 8 cm in height and 1 m wide. The natural chan- i.e., t e region of groundwater drained by a water- nel was deeper (100 cm) and although there was no course, was tmlte o I 3 io� om the ditches.spoil line, it was partially flanked by a natural berm Thus, e 10-m st m t ratu W as—beyond---the influence of resulting from overbank deposition of tidal sedi- watercourse drawdown and served as the open ments. marsh control for each site. By having site-specific Since all ditches in Suisun Marsh are of the same controls, variability resulting from open marsh I age,sites adjacent to a single ditch(site SD,44 years heterogeneity was eliminated. old) and a natural channel (site SNC) were chosen Sampling Procedures.—Arthropods in both for sampling. The ditch and the channel were lo- Petaluma and Suisun Marshes were sampled during cated ca. 80 m apart, and both flowed into the same late-morning hours at 2-week intervals from I 1 August 1982 BALLING AND RESH: ARTHROPOD RESPONSE'ro DITCHES 803 highly correlated with both H' (information theory) = � and Simpson's diversity index (Resh and Balling -r 1979, Fig. 5). - l , Arthropod Biomass.—Dry-weight biomass was determined for one sampling date per month from the 1-and 10-m strata D-Vac samples at site P5(the Y ..+ Petaluma 5-year-old ditch). Specimens were overt• _'° i"z; dried at 100`C until they reached a constant weight, which was measured to the nearest 1.0 mg after they cooled to room temperature in a desiccator. Statistical Analysis.—Analysis of diversity data r over the complete year masked rather striking sea- sonal patterns. Therefore, the data were divided • "t '_;.•.: into wet season_(November through April) and dg season(1T a3-y tTiroue�'t�ctobe�to coincide with the wo seasons characterbstic of the San Francisco Bay - _ .z area's Mediterranean climate. Distances were com- - pared within each site and sites were compared at each distance seasonally by a two-way analysis of � z variance with date as the second factor. Site P8 was not included in the inter-site analysis because of its significant physical and biological differences. The Student-Newman-Keuls (SNK) procedure was used for all a posteriori multiple comparisons tests within sites and distances.The Kolmogorov-Smirnov good- ness of fit test verified that the SCI diversity data was normally distributed as predicted by Patil and Fic. 2.—Spate all-terrain %chicle with v-shaped plow Taillie(1976). Arthropod biomass values were com- used to construct shallow recirculation ditches connecting pools to natural channels. pared with the \\'ilcoxon signed ranks test. Signifi- cance levels of 0.05 were used for all statistical tests. }•_ical Factor s Analyses November 1977 through November 1975, although Vegetation and Ph }• the sampling schedule was modified during periods In addition to the arthropod community an�sis, of winter flooding (December 1977 through March several bioloqicalTn_j2_2L—sic_s parameters were also 1978). Arthropods were collected using a 3.5-horse- examined in Petaluma Marsh, Incluutng: Salicornia power(ca. 2.6-W) D-Vac suction device,fitted with iomass, water table height, group waTer sa ffnniTy, a 0.25-mm-mesh nylon collection bag. Each sample and soil surface sa inity. easuremenTihe ee pa- consisted of 30 pooled subunits (established as the rameters require major disturbance of the sampl- point at which the cumulative species-abundance ing sites, and was therefore delayed until after the curve became asymptotic), with each subunit being arthropod sampling program was completed. Be- the firm placement of the 0.0314-mz suction cone cause access to the northern section of Petaluma against the ground for 5 sec. The amount of habitat Marsh was limited after the arthropod studies were represented by each sample was 0.942 m'-. Along completed,physical measurements at the 8-year-old each stratum,the subunits were taken sequentially 1 ditch were made less regularly than at other sites. m apart, beginning at a randomly chosen starting Salicornia Biomass.—Estimates of the above- point. ground biomass of Salicornia were made by the bar- Samples were placed in an ice chest immediately vest method.Ten 0.25-m2 samples at each 1-and 10- after collection and within 3 h placed in Berlese- m stratum within sites P5 (5-year-old ditch) and Tullgren separation funnels for 24 h,which was suf- PNC(natural channel)were clipped to ground level, ficient time to extract all live insects from the sam- dried at 105`C for 48 h, and weighed. Samples were ples. Given both the small size (0.5 to 2.0 mm) of taken at the beginning(early spring) and end (early many of the arthropods and the large volume of de- autumn) of the growth period. tritus in the samples, Berlese-Tullgren extraction Water Table Height.—Two transects perpendicu- was found to be the most efficient and representa- lar to the watercourse at sites P2, P5, P8, and PNC tive method for sorting samples. were established to measure water table levels. Arthropod Diversity.—Arthropod diversity of Standpipes 2.5 cm in diameter and 144 cm long were each sample was estimate wit t e equential implanted at 0.0, 0.1, 0.3, 0.7, 1.5, 3.1, 6.3, 12.7, Comparison Index (SCI) (Cairns et a].�1965 .. The and 25.5 m from the watercourse edge. Water table SCRs ann unbiase es�o the normally distn- levels were reeorded during low tide for each neap I b rUd rt—i�son s cliv city index att an ai to series of tides (biweekly)for 1 year. Measurements 1_ Empirically we have shown that when made when tidal waters filled the ditch were used to species-level identifications are used, the SCI is determine the extent of groundwater recharge, i.e., 1 ' 804 ENVIRONMENTAL ENTOMOLOGY Vol. 11, no. 4 the distance from the edge of the ditch that the tide 60 replenishes the groundwater supply. Groundwater Salinity.-The salinity of the groundwater within each standpipe was measured 50 with a refractometer once in the wet season and twice in the dry season. Soil Surface Salinity.-The salinity of the marsh 40 t, y '�► surface was determined from soil cores 6 cm in di- a �`` ameter and 2 cm deep. The oven-dried cores (50`C o for 1 week) were separately blended with distilled LL 30 water to a 1:5 dilution (by weight), and the salinity o of the resulting solution %vas measured with a con- 24 ductivity meter. Five cores were taken at the 1-and 20 10-m strata of sites P2, P5, and PNC twice during the dry season. Results to Arthropod Anal)•sis Petaluma Alarsh Fauna.-The domiazw_Qrde.L.in o _ o e e e e o _ i Petaluma Marsh,the Acarina,constituted over 51% < a E g € g E 8 of tFie total ear's captures (Fig_3and was repre- t 4 sented by 10 spectes. The second most abundant J f order, the Diptera (14.6%), %vas characterized by FIG. 3.-Numerical composition of arthropods collected high species richness but was dominated by an unde- with a D-Vac in Petaluma Marsh,November 1977 through scribed chironomid midge. Pseudosmittia sp., and November 1978. the brineflies,Atissa litoralis(Cole),Scatella (I\reo- Scatella)setosa Coquillet,and Psilopa(Ceropsilopa) old ditch. In contrast,at neither the 8-year-old ditch coquilletti (Cresson). The Hemiptera (9.3%) were nor the natural channel was this trend of increasing dominated by the leafhopper, Streptanus confinus diversity with increasing distance from watercourse (Reuter). Among the spiders(Araneida,7.2%),the apparent. wolfspider, Pardosa ramulosa (McCook), was the Conversely, during the dry season diversity near most abundant species in terms of both numbers and the ditches increased;all three ditched sites had sig- biomass. Some combination of the above species m tc'f ntly'_higher diversity (P <_0.05),aLt 1-and.3 m generally dominated any given sample throughout thanthe.open marsh(10 m)(Table 1).Furthermore, t the year and as a result greatly influenced the diver- the diversity near the natural channel was also sity of that sample. higher (P = 0.08) at distances of 1 and 3 m than at Arthropod Diversity and Biomass.-During the 10 m. wet season-in_Petaluma..Martih, Lthropod diver y When diversity estimates between Petaluma sites ' estimates for the 1-m stratum at the 5-year-old ditch P2, P5, and PNC were compared, values at the 1 ,\•ere signt,lcf an`tly,lowei(P 0. _1 tF-an thos� e'at t ie and 3 m strata were lower in the ditched sites than 3- or 10 m strata (Table 1). A similar pattern (Fut the natural channel site (P < 0.01) during the wet nonsignificant,P = 0.15),was evident at the 2-year- season(Table 1).No significant differences were ob- ' Table 1.-Mean±SD of Petaluma Marsh seasonal arthropod diversity° Site i in 3 m 10 m P Wet seasonb 2-Year-old ditch 0.54± 0.14 0.64± 0.11 0.65 ±0.22 0.1 5 5-Year-old ditch 0.54±0.12' 0.61 ± 0.10 0.62±0.11 0.05 Natural channel 0.74± 0.09t 0.76± 0.06t 0.71 ±0.08 0.25 P <0.01 <0.01 0.30 8-Year-old ditch 0.59± 0.14 0.48± 0.12 0.55±0.13 0.34 Dry seasonc 2-Year-old ditch 0.87±0.09 0.82± 0.16 0.76± 0.16• 0.05 5-Year-old ditch 0.79± 0.12 0.76± 0.10 0.68±0.130 <0.01 Natural channel 0.81 ± 0.14 0.85 ± 0.06 0.74±0.10 0.08 P 0.18 0.12 0.29 8-Year-old ditch 0.58±0.09 0.42± 0.15 0.33±0.15• <0.01 'Significance levels (P) are reported for each analysis of variance.The 8-year-old ditch was not included in inter-site comparisons. •, Value is significantly different from others in the same row(intra-site comparisons);t, significantly different from others in the same column. bNovember(1977)to April(1978). cMay to October(1978). August 1982 BALLING AND RESH: ARTHROPOD RESPONSE To DITCHES 805 Table 2.-Mean±SD of Suisun Marsh seasonal arthropod diversity" Site l m 3 m 10 m P Wet seasonb 44-Year-old ditch 0.68 ± 0.10 0.64 ± 0.13 0.65 ±0.20 0*•8 Natural channel` 0.81 ± 0.17 0.77± 0.12t 0.71 ±0.15 0.39 P 0.20 0.03 0.56 Dry seasonc 44-Year-old ditch 0.81 ± 0.09 0.82 ± 0.09 0.81 ± 0.10 0.45 Natural channel 0.87± 0.07 0.85 ± 0.06 0.80± 0.13 0.15 i P 0.18 0.17 0.24 "Significance levels (P) are reported for each I analysis of variance. ', Value is significantly different from others in the same row (intra-site comparison); t, significantly different from others is same column (inter-site comparisons). bNovember(1977)to April(1978). cl`fay to October(1978). Iserved among sites at any distance during the dry 250 season(Table 1),or among sites at the 10-m stratum during either season. I 10 .�,.m At Suisun Marsh there were no significant differ- zoo ences in intra-site diversity during either the wet or , the dry season (Table 2). The only significantly dif- ferent inter-site comparison at Suisun Marsh oc- E 50 curred during the \vet season (Table 2), hen the natural channel 3-m diversity values were higher a loo. than those at the 44-year-old ditch (P = 0.03).� o_ Total arthropod biomass vas examined at the 5- © / year-old ditch in Petaluma Marsh. No significant dif- 50 ferences \were found between the 1-and 10-m strata (Fig. 4). 0 Vegetation and Ph)'sical Factor Analj'ses N D J F M A M J J A s 0 N Salicornia Biomass.-Spring Salicornia standing 1977 1978 crop, which includes only the A oody, perennial FIG.4-Comparison of arthropod biomass at the 1-and component, was not significantly different between 10-m strata of site P5 (5-year-old ditch) in Petaluma 1- and 10-m strata at the 5-year-old ditch (Table 3). Marsh. However, standing_crop 1 m from the natural chan- nel was significantly higher than 10-m-from the_Ca tu- ral channel(P = 0.02�.Similarly, 1978 pilot Sbmass Dater Table Height.-Biweekly measurements studies at the 8-year-old ditch also showed the 1-m during neap_tides indicated that tFie`d-r9wdown-of s woody component to be higher than the 10-m com- ltc e an natura c anne s on y exextende�about-3- ponent (P = 0.08). Autumn standing crop differ- m-Troth their banks"(Fig: TFie mean wet-season ences only occurred in the 8-year-old ditch pilot waifer leV'eT u7as about 5 io 10 cm above the mean studies, with the 1-m distance again greater than the dry-season level,although there was no difference in 10-m distance (P = 0.01). the shape of the drawdown curve. The shape of the Table 3.-Distance comparisons of S. vbVnica aboveground, dry-weight biomass(z±SD in g/m2)in Petaluma Marsha Season Site i m l o m P 77 Spring 5-Year-old ditch 1,758 ± 355 1,723 ± 512 0.82 Natural channel 2,116 ±463 1,560± 362 0.02 8-Year-old ditch 1,256 ± 305 980 ± 320 0.08 Autumn 5-Year-old ditch 3,220 ± 876 2,782 ± 874 0.32 Natural channel 2,720 ± 542 2,646 ± 511 0.75 8-Year-old ditch 2,513 ±455 1,957± 294 0.01 "Significance levels (P) are reported for each r test between distances uithin the same site. The 5-year-old ditch and natural channel spring samples were taken on 22 March 1979, and autumn samples were taken on 28 September 1979. The 8.yearold ditch spring samples were taken on 12 March 1978,and autumn samples were taken on 2 Octo- ber 1978. 806 ENVIRONMENTAL ENTOMOLOGY Vol. 11, no. 4 2.5 f march surface 50 � o a Aug 1_60 25 seal I9e0 ... - -c rechorye -•'... 2.3 r 40 _.-.... __ __.. ------•- - -- 30- - 2.1 --- rater table � II Feb 1980 I i 20 r i 1.9 natural cho nn<I IO natural channel 1.7 0 I E 2.5 50 2.4 0 40 J _j o ' 30 2.3 w M----------------------------- t O 2.2 Z 20 © J Q 2.1 Sryr-old ditch < i0 5•yr-old ditch S LD 2.0 0 w = 2.5 50 2.4 40 ------• 2. --- 30 2.2 20 2.1 2-yr-old ditch 2•yr-old ddch to 2.0 p 0 5 10 15 20 25 0 5 10 IS 20 25 DISTANCE FROM DITCH (m) FIG. 5.-Seasonal water table drawdo\vn and mean high DISTANCE FROM DITCH (M) tide recharge curves of the natural channel, 5-Fear-old FIG. 6.-Groundwater salinity in water table standpipes ditch, and 2-year-old ditch in Petaluma Marsh. Note the at the natural channel, 5-year-old ditch, and 2-}'ear-old 1 compressed scale of the natural channel y-axis. Mean ditch on three sampling dates in Petaluma Marsh. lower low water (MLLW) is the average height of the lower of the daily low tides. result of greater tidal flushing near the water- courses. ' drawdown curve at the 8-year-old ditch was the same as those at the other sites, but measurements Discussion ranged 10 to 15 cm higher. Water table measure- Results of diversity analyses in Petaluma Marsh ments durin_Q ditch-full tides in icy_ ed that a tide at indicate tFat ditches do affect the arthropod commu- mean hi-£h wate.�-_N_ould_eause recbarge_SQ_eatend pity;altfiouzh the influence is seasonal. During ^the _ about 2.5 m from the watercourse (Fig. 5). dry season, the pattern of arthropod diversity is -Cioundu%titer Salinity=SalinitieSZSf the ground- similar to that near the natural channel (i.e., diver- water initially increased rapidly with distance from the watercourses and then began to level off (Fig. 6), paralleling the pattern of water table heights (Fig. 5). At the natural channel,the pattern was dis- rupted by a decrease in mean wet-season salinity at 6 Table 4.-Mean ± SD of salinities(0/00)at soil surface m. This coincided with a decrease in water table (1:5 distilled water dilution) in Petaluma Marsh;all 10-m height (Fig. 5, natural channel) and reflected the strata are significantly higher than 1-m strata when com- presence of a nearby underground seepage leading pared by t tests(P<0.05;n=5). to the natural channel. The pattern of salinities at the 8-year-old ditch, taken during the wet season site 1 m 10 m only,was similar to the other ditches,although open 1 July 1980 marsh salinities in this northern section were 10 to 2-Year-old ditch 3.9 ±0.42 6.9 ± 0.34 200/oo higher. 5-Year-old ditch 5.5 ± 0.71 13.9 ± 1.35 Soil Surface Salinity.-Soil salinities on both sam- Natural channel 4.5 ±0.72 9.8 ± 4.14 pling dates were significantly lower near the ditches 15 August 1980 and natural channel (1-m stratum)than they were in 2-Year-old ditch 4.5 ±0.53 8.8 ± 0.50 30 the open marsh Table 4). These results parallel the 5-Year-old ditch 4.2 +0.74 19.4 ± 2.12 P ( ) p Natural channel 4.2 _0.74 9.4 ± 2.12 groundwater salinity gradients and are probably a August 1982 BALLING AND RESH: ARTHROPOD RESPONSE To DITCHES 807 - sity decreases with increasing distance from the 1979) and more shelter (van Emden and Williams watercourse). During—the--wet season, the pattern is 1974), or, particular to salt marshes, refuge from reversed at the 2-year-old and 5-ear-oTd d—fetes high winter tides. diversity increases with increasing distance The common occurrence of high Salicornia woody from the ditch) but not at the 8-year-old ditch and biomass near channel margins and underground natural channel. The biological and physical factors seepages (Chapman 1974) suggests that, in times I examined suggest several reasons for the seasonal ditch margins should also be expected to have higher trends. woody biomass. This has already occurred at the 8- Higher arthropod diversity values near the ditches year-old ditch but not at the two younger ditches. If and natural channel in the dry season support the the"fe is an`eventual increase in woo y iomass near I presence of distinct physical or biological gradient(s) di c-ges, then th`e wet=season wasfi out o —insects perpendicular to these watercourses.Our results de- would a eliminated an3 we would expect a con- fine several gradients: increasing water table height vergence of ditch with natural channel diversity pat- (Fig. 5). decreasing daily water table flux (Fig. 5), terns. 1 increasing groundwater salinity (Fig. 6), and in- --Tfie high plant species diversity, low water table creasing soil surface salinity (Table 4). level, and low tidal water salinity of Suisun Marsh The high salinities and frequent tidal inundations are far less affected by the ameliorating influences of which define salt marsh habitats greatly limit ar- mosquito control recirculation ditches than they are thropod species richness (Heydemann 1979, Foster in Petaluma Marsh. Therefore, both dry-season and Treherne 1976). When these conditions are al- changes in food quality and wet-season wash-out layed, energetic costs of survival decrease (Foster should be minimal in Suisun Marsh; this would then and Treherne 1976), and less tolerant species are account for-our observation that arthro2rver- able to invade and become established. For exam- sides are unaffected by tiie presence of ditches in pie, lower groundwater salinity and soil surface sa- linity can be expected to improve food quality of In the past two decades, considerable attention both live and detrital Salicornia (Bro Larsen 1951, has been devoted to maintaining the integrity of the ' Regge 1973, Weigmann 1973, Flowers et al. 1977), remaining unaltered San Francisco Bay marshes,in- thereby increasing the number of species capable of eluding the ecological consequences of management tolerating these conditions. Similarly, several salt programs such as the construction of recirculation marsh insects have been shown to prefer more well- ditches for mosquito control. The results of our ar- drained soils(Bro Larsen 1951, Luxton 1967,Weig- thropod studies suggest that these ditches either` mann 1973, Foster and Treherne 1976); apparently have noapparent effeciTe.g., no elf erenc(,Zs)D-U by doing so,they then escape the stress of prolonged t i op7RTiomass_in_Isetaluma A4arsl r rta hropod periods of inundation in the open marsh. Thus, the diversity in Suisun 1`4arsh),or they have a temporal dry-season increase in species diversity near ditches of of ct-(e.g.,' arthropod diversity in Petaluma would be expected, due to the local amelioration of Marsh), in that patterns exhibited at ditches should harsh physical conditions. eventually`converge with Those at natural'channels. During the wet season, water table height and Tfiere o>` re,with respect tnihe arthropod communi- ' groundwater salinity should have little effect on ty, we enncltide that mosquito contol:recircu7a`tion food quality because Salicornia is dormant.Further- ditches can..be.considered an ecologically acceptable more,soil surface salinities in the wet season are un- management_approach_ for San F_ran_ci'coTBay iformly low, due to low rates of evaporation and marshlands. leaching of salts by rain. Nevertheless, there occur - low 1-m diversities at the 2-year-old and 5-year-old Acknowledgment ditches during the wet season which result from a re- We thank Mark A. Barnby and Joshua N. Collins duction in insect densities and domination by soil (University of California, Berkeley) for field and mites. Evidence suggests that this could be caused laboratory assistance, the CMVCA Coastal Region by high winter tides that wash insects out from areas Mosquito Abatement Districts for their support and near watercourses (e.g., Luxton 1967, Foster and cooperation throughout this project,and Miguel Al- Treherne 1976). The propensity for wash-out might tieri (University of California, Berkeley) and Guy ' be alleviated in the natural channel and the 8-year- N. Cameron (University of Houston)for their com- old ditch (where low 1-m diversities are not ob- ments on this manuscript. Support for this project served) by the high biomass of the Salicornia woody was provided by University of California Mosquito component at 1 m compared with the respective Research Funds. ' open marsh samples (Table 3). The increased l2lant structural diversity offered by the eavv wondv gnat REFERENCES CITED ponent can be an important correlate of arthropod Balling, S. S.,T. Stoehr, and V. H. Resh. 1980. The ef- diversity (e.g.,'Murdoch et al. 19 atley and fects of mosquito control recirculation ditches on the t ac a n increase in insect diversity fish community of a San Francisco Bay salt marsh. due to increased plant structural diversity might be Calif. Fish Game 66: 25-34. attributed not only to more food resources,but to a Barnby,M.A.,and V.H.Resh.1980.Distribution of ar- more varied microclimate (Tallamy and Denno thropod populations in relation to mosquito control re- SOS ENVIRONMENTAL&NTomOLOGY Vol. 11, no. 4 - circulation ditches and natural channels in the Anim. Ecol. 36: 257-277. Petaluma salt marsh of San Francisco Bay.Proc.Calif. Mairdoch,W.W.,F.C.Evans,and C. If. Peterson.1972. Mosq. Vector Control Assoc. 4S: 100-102. Diversity and pattern in plants and insects_ Ecology 53: Bro Larsen, E. 1951. On subsocial beetles from the salt- 819429. marsh,their care of progeny and adaptation to salt and Pahl,G.P.,and C.Taillie.1976.Ecological diversity:con- tide. Trans. Int. Congr. Entomol. 9: 502-506. cepts,indices and applications. Proc. Int. Biom.Conf. Cairns, J., Jr., P. W. Albaugh, F. BnSSCV, and NI. D. 9:383-311. Chanay. 1968. The sequential comparison index-a Provost,N.NV.1977.Source reduction in salt-marsh mos- simplified method for non-biologists to estimate rela- quito control: past and future. Mosq. News 37: 689- tive differences in biological diversity in stream pollu- 698. tion studies. J. Water Pollut. Control Fed. 40: 1607- Re=e, H. 1973. Die Blaitlaus-Arten (Hexapoda, 1613. Aphidoidea) des Gezeitenbereichs der Nordseek6ste Chapman,V.J. 1974. Salt marshes and salt desers of the Schleswig-Holsteins. Faun. bkol. Mitt. 4: 241-254. world. Interscience, New York. 494 pp. Resit,V.H.,and S.S.Balling.1979.Ecological impact of Flowers. T. J., P. F. Troke, and A. R. Yeo. 1977. The mosquito control recirculation ditches on San Francisco mech.dnism of salt tolerance in halophytes.Anr.u. Rev. Bay marshlands: preliminary considerations and ex- Plant Phvsiol. 2S: S9-121. :erimental design. Proc. Calif. Mosq. Vector Control Foster,W.A.,and J.E.Treherne.1976.Insects of marine Assoc. 47: 72-78. saltmarshes: problems and adaptations. In L. Cherie Shisiler,J. K., and D. A1. Jobbans. 1977. Salt marsh pro- fed.]. Marine insects. North-Holland Publishing Co., ductivity as affected by the selective ditching technique, Oxford. 581 pp. open marsh water managernent. Mosq. News 37: 631- H2tley,C.L.,and J.A.Macvtahon.1980.Spider commu- 636. nity organization: seasonal variation and the role of TalLamy, D. W., and R. F. Denno. 1979. Responses of vegetation architecture.Environ. Entomol.9:632-639. sap-feeding insects (Homopaera - Hemiptera) to sim- He}demann,B. 1979. Responses of animals to spatial and plification of host plant structure.Environ. Entomol.S: temporal environmental heterogeneity within salt i021-1028. marshes. In R. L_ Jefferies and A. J. Davy feds.), van Emden,H.F.,and G.F.NN-i liams.1974.Insect stabil- Ecological processes in coastal environments. izy and diversity in agro-ecesystems. Anru. Rev. En- Blackwell Scientific Publishers, Oxford. 6S4 pp. tomol. 19:455-475. Lesser, C. R., F. J. Murphey, and R. W. Lake. 1976. We amann, G. 1973. Zur Okologie der Collembolen and Some effects of grid system mosquito control citching Oribatiden im Grenzbereich Land-Meer (Collembola, on salt marsh biota in Delaware. Mosq. News:6:69- Insecta - Oribatei, Acari). Z. Wiss. Zoal. 186: 295- 77. 91. Luxton, M. 1967. The ecology of saltrrarsh Acanna. J. Tiaal Circulation Alteration for Salt Marsh Mosquito Control VINCENT H. RESH trol:increased tidal flushing of soils occurs adjacent to ditches STEVEN S_ BALLING compaired with that in the open marsh,thereby reducing ground- Division of Entomology and Parasitology water and soil surface salinities and water table freight;primary pro- University of California,Berkeley ductivity of S. virgirnca, as determined by both the harvest method Berkeley,California 94720 and infrared photographic analysis,is higher directly adjacent to ditches than in the open marsh;dcstribution of selected arthropod ABSTRACT x Mosquito control ditches designed to increase tidal populations is similar at ditches and natuW channels,although ar- circulation are widely used as a physical control alternative to inseclti- thropodl community response differs seasonally,aquatic invertebrate cidal applications.The impact of such d ilching on Pacific Coast biomass is similar witthin ditched and natural ponds,but diversity is marshlands was largely unknown before this five-year study of im- lower in ditched habitats;ditching increases fish diversity and density pact in two types of San Francisco Bay salt marshes,a Saiicornia wir- by improving fish access from tidal channels;ditches provide addi- ginica(pickleweed)monoc fur and a mixed vegetation marsh.R� tional salt marsh song sparrow habitat,although ditches are less suits of our studies sugges at ditches cause less environmental preferred than naturall channels or sloughs.Management criteria can disturbance than insecticidal applications.The article describes the be used to design ditches that provide effective mosquito control following environmental consequences of ditching for mosquito con- and reduced environnnental impact. An outgrowth of the environmental movement has been a between natural trial channels and ponds where mosquito search for alternatives to technologies that are environmentally breeding occurs (Figure 1(B)). These ditches are not intended disruptive. In some cases, however, the alternatives have also to drain ponds but rather to increase the frequency of tidal resulted in environmental problems. For example, the reper- flooding and improve access for predatory fish. In addition,the cussions of pesticide use in the control of insects have been well larger, permanent pon s t at do not support mosquito larvae documented (for example, Edwards 1973, Luck and others remained unmodified. On the Pacific Coast, mosquito abate- 1977), but alternatives to insecticides can have deleterious ment personnel have used an all-terrain vehicle to dig and effects as well. The mosquitofish (Canibusia affirms), which is maintain these connecting ditaes. The success of shallow, native to central North America, has been transported world- connecting ditches as a mosquito control measure has been well wide for the biological control of"mosquitoes. However, it has established (Provost 1977), as has their cost effectiveness been shown that mosquitofish may invade natural habitats and (Teleford and Rudker 1973, National Academy of Sciences replace native fish populations ('Myers 1965). In addition, 1976, Hansen and others 1976). However, for Pacific Coast when stocking levels of mosquitofish are too low, mosquito marshlands, the environmental effects of these ditching prac- production may actually increase(Hoy and others 1972). tices are largely unknown. < In the case of salt marsh mosquitoes,a popular alternative to In this paper, we discuss the results of a five-year study that chemical control is a habitat-manipulation approach using examined the environmental consequences of ditching for ditches to increase tidal circulation in marshlands. Habitat mosquito control in Pacific Coast salt marshes. This research manipulation in marshes is not a new approach; in about 4501 was done in the two, types of salt marshes characteristic of the BC, Empedocles drained marshes in Sicily for agriculture,and San Francisco Bay. The first type was represented by Deta- in 1831 the Pontine marshes near Rome were drained to reduce luma Marsh, where the plant community is dominated by a the incidence of malaria. single species, picklrweed (Salirornia virginica). The second In North America, salt marsh habitats have been manipu- marsh type was represented by Suisun Mann,where the plant gated for mosquito control since the turn of this century community is more diverse and the inundating waters are less (Provost 1977). Two fundamentally different ditch designs saline. have been used in control efforts. In the 1930s, prior to the extensive use of insecticides, a system of deep, parallel ditches was most popular figure 1(A)). These ditches purposely Response Of the Physical Environment to Ditching lowered the marsh water table to drain marsh ponds and eliminate mosquito larval habitat. However, lowering the The low porosity of San Francisco Bay salt marsh soils can --eater table significantly altered salt :harsh plant composition be seen from examining the inFuence of tides on water table and,consequently, affected the entire food web (Daiber 1974). height. Drainage of the water table by ditches at low tide is More recently, ditches have been designed simply to increase limited to about 3 er 4 m rom t e its an s water tab e, tidal circulation by means of a system of shallop.- connectors FiRure?(A . nen 6itcries are I Jilcu uy nign ticles,ticlal water KEY WORDS 7adal circulation; Mosquito control ditches Environmentar replenishes the water table to a distance of 2 to 3 m from the response;Pacific coast marshes banks (recharge, Fi_ure 2(A)). Therefore, only the soils adja- Environments!!.aanagement.Vol. 7,No. 1,pp ?9-84 0364-152X/83/0007-0079 S01.20 G 1983 Springer-Vertag New York Inc. 80 V. H. Resh and S. S. Balling A B r v y at r Figure 1. Ditching designs for salt marsh mosquito control using:(A)a system of deep,parallel ditches that purposely lower the water table,and (B)a system of shallow connectors. cent to the ditches are alternately drained and recharged during _ A each tidal cycle. The resultant flushing causes an amelioration E 2.5 marsh surface of the normally harsh salt marsh conditions. For example, J 2.4 I groundwater salinity near a ditch is significantly lower than in _ recharge the open marsh (Figure 2(13)). Similarly, during the dry w 2.3 _ season, a gradient of increasing salinity with increasing dis- o - lance from the ditch or natural channel is found;during the wet c 2.2 Muter table I season, rain effectively eliminates this gradient. t— 2.11 This pattern of localized physical changes has been impor- 0 tant to the experimental design of many of our biological = 2.0 I studies (Resh and Balling 1979). Instead of trying to compare ditched and unditched marshes, which might differ drastically 50 B in a variety of factors owing to slight differences in elevation, we were able to compare measurements made at ditch margins 40 to those made at various distances from these margins. We } 30 considered the 10-m distance from the ditch to represent the F unaffected, open marsh. This design, with a control for each J 20 I sampling site, allowed us to adjust for marsh heterogeneity. < 10 CD 0 IResponse of Vegetation to Ditching 0 5 10 15 20 25 At Petaluma Marsh, where the vegetation is essentially a DISTANCE FROM DITCH (m) monoculture of pickleweed, we considered productivity to be Figure 2. (A)Mean water table drawdown and recharge curves and the best indicator of possible environmental perturbation. (B) groundwater salinities in relation to distance from a ditch in Comparisons of annual above-ground pickleweed production Petaluma Marsh, Ditching for Mosquito Control 81 tit. N a}�4 •t 1 '4 J`•''t.. 'TAt...:� s �-.l.-+1• 'Y s. :� Y •'Y.: 7i.r�vt--i-�i: i Y w r �� a's��' �•'�-�'Y- ,ff�y�•� �.�3 �� r f 'a' t iy{? y..4` v {ia• ,�- ` , L,�3 "./�; •��.•t as '`+�f �.� ' . la:� y ��4 Ij ♦ fs,f}aaei Xf Coat �x.,� .wr tx c rt i '� Mw .\�CY,{.f_f;��(v;}:h� .>X ec�`���y�FY.�'" L �4 �'•a� 4.A:� <....a�a w`� r •' ^t'M�a �y,Y•S''aa'9 a4 r t�''�i# fiJ�4 ?' - ?•C" .•a t •a".v. '1 �•f r. t .. y�t'�'a{ •t; r'�yti/'s['h` Z �ryr�i��-ESL t a �\- `y '�- 1'6� )• ''�e.• gyv,�l t' S y�py'17��'��I'^.(}]1�[�ly.} f�'•Y .1'K A 4a •V 4 � y.y.—`.x l.. �:� :l r�S� y5'rA ,/, ; _.e j� •tr "�' t M'`''212YJ F`f �..,.� '.• �}'�'.r c3� -K�`9 yt► ✓7th SI.Lt� •'rC y.- t J � :•F.,Y 1 7Pa . 'YiiY r' R2{ '''�• '� •t •�'"tR =• i �'.a. V I i Y N• fi t •s-�1': .'�:.. 7 .r 'i � •, �j��'r,'. L �• a :S�S�� �� ;..,,: -awe���a ��'•. a�� �� .� •� 3_�Y ti� r.}v '+'#„Y,'�•C,y'�.4 - v ��� S• .z v S��`i}�. ��y x r f a `` :f rr JT•,� X -Yr'y'"a�v� � ^ "..�,,��:tT���a^aKLFr.•'Vy��'y:x.us ��,t•+r(ti:f''�.'� c �j�.:l..•. �.�. a "k"� '�7j�y ��a �y_S t c•d t •F w 'S`S. _ p,{a.,M t i� __ ,-�,�µl. Y � s� ° t,a..�c��t F,a .( .r• t7f� _Ik y+t. \ .�� y Sa j�+�..ya• 1 Y,�� ;,i�f;'y `�f ti� .•�t�i`y-��[��`a''",N.� � /� y yq �,• "�*' �r•+'�' t... t�'�+ �y��,�1 j'�^L tf'��f.4,�'^9.. �t, j"�TJ ,S rr. § .i �`'ji y'�.," ,� j ;r. ti.R,�J�5Y'I��1 r. r(a. ,� � ��(R c� <► ^`��1:: M ,\ 1'!A�'w�•Jk�: �.. �a a. .S-... _. .__.....- .k+ .l S k� !. ..r'.. iFigure 3. :\trial infrared phouograhh of Petaluma \larsh. 1 (dry weight) among sites in the open marsh and sites adjacent areas of higher plant growth and vigor; such areas are to a ditch and a natura channel indicated that production %ras commonly adjacent to ditches(Figure 3). substantially higher near a ditch (1462 ; m ,'vO than in the Since the second marsh type, represented by Suisun !Marsh, open marsh (1073 a/in yr). In contrast, production near a has far more plant species than the Petaluma A4arsh, we used I natural channel was much lower (G(14 y„ m-, yr . I Ile ocser plant species richness and percent cover as indicators of productivity near the natural channel %.'as a result of a environmental response. Estimates of these parameters were significantly higher biomass of the woody, perennial c•ompo- made every 3 m, beginning directly adjacent to a ditch and nent of pickleweed. The cice•urrenc•e of heavier, woody pickle- continuing perpendicularly to 30 m. Results showed that the weed implies that productivity was prcvrousl)• hi-her, but that average number of plant species significant y ecrease with increasing plant maintenance costs have since reduced produc- increasing distance from the ditch—that is, most species tivity. Although woody biomass near the ditch was relatively occurred near the ditch rather than in open marsh (Figure low, our studies indicate that, if pickleweed near ditches 4(A ). continues to be highly productive, the biomass pattern in When we examined the four dominant plant species, we ditched habitats should eventually converge with that in natu- found that Dislichlis spicala(salt grass)and faumea carnosa(a ' ral channel habitats (Balling and Resh in press). fleshy, yellow-flowered composite) were unaffected by ditch Aerial infrared photographs also show this ditch edge-effect. presence(Figure 4(B)). However,there were significant differ- The lighter areas in black and white infrared photos indicate ences in the distribution of funcus ballicus(baltic rush) and S. 82 V. H. Resh and S. S. Balling (V 5.0 / � 1• � A to I-m strata ' 09 N 4.0 ���.-•. O 08 3.0 wno.of species = O7 K f f Ln r U 2.0 ` cn Ob W n F- 05 / U) 1.0 F- V) 10•m strata ' O Cr 04 Z 0 w 0 03 50 Dislich/is spicolo B 02 ' a: 40 01 W O 30 00 V ✓oumeo cornoso N D J F I M I A M J J A S O N i 0 20 - .- 1977 1978 10 Figure 5. Seasonal variation in terrestrial arthropod diversity at two Petaluma Marsh ditched sites;comparison of diversity at the ditched 0 1-rn strata with that at the open marsh 10-m strata. 30 Salicornia virpinica C ' > •-� several distances from ditches and natural channels. Results O 20 _ ✓uncus bo/Iicus indicated that the presence of a ditch had seasonally different to / - . effects on terrestrial arthropod diversity.Duringthe wet season • ___. ___.-__-.-- (November through .April in the San Francisco Bay Area), ' o diversity near a ditch was significantly lower than in the open 0 3 e 9 12 Is is 21 24 27 30 marsh; during the dry season, diversity near the ditch was DISTANCE FROM DITCH (m) significantly igher ( Igure ) . owever, near the natural channel, wet season species diversity was not significantly Figure 4. (A) 1.fean number of species, (B) percent cover of lower than in the open marsh.This higher wet season diversity Distichhs spica/a and faumea carnnsa, and (C) percent cover of(uncus ballicus and Salicornia virginica,in Suisun Marsh. is probably related to the presence of heavy, woody pickleweed ' near the natural channel (see above), which serves to shelter arthropods from higher winter tides. If, as our vegetation virginica (pickleweed) (Figure 4(Q).Apparently, the Bushing studies have suggested, the woody biomass of pickleweed near of the soil near ditches lowers groundwater salinities and ditches increases over time, then we expect that the pattern of allows baltic rush to displace pickleweed along ditch edges wet season arthropod diversity near a ditch should increase and (Balling and Resh in press). eventually converge with that found near a natural channel (Balling and Resh 1982). In fact, the influence of ditches on ' 2 distribution patterns of specific arthropod populations was Response of Invertebrates to Ditching similar to that of natural channels for seven of nine species Arthropods have been shown to be among the best indicators examined (Barnby and Resh 1980). of environmental perturbation in a variety of biotic systems Recirculation ditches are successful because they altuhe (Lenhard and Witter 1977, Hellawell 1978, I-Iawkes 1979). hydrolo�v of salt marsh temporary ponds and this alteration Therefore, for the past several years we have examined the serves to eliminate mosquito larvae. However, the impact that response of the terrestrial arthropod community and the ditches have on mosquitoes suggests that other aquatic inverte- aquatic invertebrate community to ditches. brates might also be adversely affected.Our studies have shown Diversity was used to examine the terrestrial arthropod that the environmental characteristics of salt marsh ponds are community because it is a summary measure of the number of predominantly influenced by tidal inundation, which varies species and individuals in the community. Arthropod diversity along an elevation gradient. As elevation increases relative to was based on D-vac samples taken biweekly for one year at mean higher high water (MHHW), pond depth, salinity Ditching for Mosquito Control 83 range, and percent algal cover increase, whereas temperature 1.0 A range and the frequency and duration of tidal inundation N ' decrease. When a pond is ditched, its position along the 1 elevational gradient is effectively lowered. To measure the impact of ditching on non-target aquatic species,we compared N 0.5 the aquatic invertebrate communities of ditched and natural g M` ponds in Petaluma Marsh. Biomass did not differ significantly m between these ponds during any time of the year (P- 0.684; 0.0 ' Figure 6(A)). Species diversity, however, was significantly higher in the natural ponds (P— 0.001) throughout the year (Figure 6(B)). This pattern was due to differences in species B richness—that is,the number of species increased with increas- ing elevation above %.IHHNV. 1 1 I.0 The numerically dominant aquatic arthropod in Petaluma A4arsh is the water boatman Tric ocurixa relicu ata. Distribu- tion studies of 7. reliculata showed that natural temporary ponds—those that produce mosquitoes—supported 7. relicu- >_ 0.5 Wet season lata densities that were 50 to 80% lower than those in larger dry season. permanent ponds—those utse t at o not produce mosquitoes. The ' natural temporary ponds apparently dried up too frequently O 0 D D D N N N for 7. reliculata to compete a generation during its main reproductive period in spring and summer. However, when -23-21 -15 -9 0 6 ' these ponds are ditched so that water remains in them between POND HEIGHT RELATIVE TO MHHW (cm) successive high tides,they can support a breeding population of Figure 6. (A) ;Mean aquatic arthropod biomass and (B) species T. reliculata. As a result, densities in ditched ponds exceeded diversity (H) during wet and dry seasons in Petaluma Nfarsh. (D: 1 those in unditched temporary ponds (P — 0.017) and ditched ponds;N:natural,unditched ponds). approached those in the larger permanent ponds. non-nesting and mated-pair densities were lower and territory ' 3 Response of Fish and Birds to Ditching size was larger. In fact,ditches were invariably the last sites to The composition of the fish communities in ditched and be chosen for nest ine. Therefore, although ditches apparently unditched sections of Albrae Slough Marsh in the south San provide additional habitat, they do not completely mimic Francisco Bay was monitored for eight months (Balling and natural channels. others 1980). This marsh is similar to Petaluma 1\4arsh with respect to vegetation and height above l\fLLW. Ten species Conclusions occurred in the ditched section, whereas only Five species were found in the unditched section. In addition, the three resident The results of our studies indicate that the addition of species (the mosquitofish Cambusia afnis, the three-spined mosquito control recirculation ditches causes several changes in stickleback Caslerosleus aculealus, and the rainwater killifish San Francisco Bay Area salt marsh ecosystems. Ditches pro- ' Lucania parua) were found in densities three times greater in mote tidal flushing of nearby soils, thereb • reducing water the ditched than in the unditched section. Apparently, ditches to a eight and groundwater salinity. This, in turn, increases increase fish diversity and densities by improving fish access salt marsh plant productivity and diversity near ditches. The from the bay to salt marsh ponds. amelioration of physical conditions also apparently increases Our studies have also been concerned with salt marsh birds. terrestrial arthropod diversity, at least during the dry season. In particular,we have compared the use of natural and ditched Ditching decreases aquatic invertebrate diversity, but does not habitats by the salt marsh song sparrow (.Melos�iza melodia affect invertebrate biomass. The addition of recirculation samuelis),which is the most abundant and visible bird found in ditches clearly improves fish access to ponds and potholes in the northern San Francisco Bay marshlands. Census data showed marsh and also provides additional habitat for salt marsh song that ditches provided additional songsnarro_� ttat ut were sparrows. From the environmental impact assessment view- less important than natural channels or sloughs. Near ditches, point(Rosenberg and others 1981)only the decrease in aquatic p�t V. H. Resh and S. S. Balling invertebrate diversity would be considered as an adverse quality. Pages 2-1 to 2-45 in A. James and L. Evison, eds., impact.p Biological indicators of water quality. John Wiley & Sons, New Comparison of our results with those from Atlantic Coast York,NY.597 pp. ditching studies suggests that individual salt marshes can differ Hellawell,J. NI. 1978. Biological surveillance of rivers.A biological substantially from each other. Nonetheless there are certain monitoring handbook.Dorset Press,Dorchester,England.333 pp. common criteriadhat should be heeded by agencies involved in Hoy,J. B., E. E. Kauffman,and A. C'.-O'Berg. 1972. A large-scale field test of Cambusia afTnis and Chlorpyrifos for mosquito control. mosquito control and marsh management: 1) ditching should Alosq.;yews 32:161-171. be avoided in marshes with sandy, porous soils, since water Lenhard,S.C.,and J.A.Witter. 1977.Insects as biological indicators table drainage would be far more extensive than occurred in the of environmental changes.Bull.Entomol.Soc.Am.23:191-193. marshes examined in our studies;2) ditching is unnecessary in Luck,R.F.,R.van den Bosch,and R.Garcia. 1977.Chemical insect marshes where elevation is below mean high water,since these control—a troubled pest management strategy.BioScience 27:606- marshes are seldom sites of mosquito breeding; 3) ditches 611. should be relatively shallow to minimize water table drainge Myers,G.S. 1965.Cmnbusia,the fish destroyer.Aust./.00l. 13:102. and, more importantly, to avoid unmanageable amounts of National Academy of Sciences. 1976. Pest control: An assessment of spoil. Assuming such recommendations are followed, we must present and alternative technologies.Vol.V.Pest control and public conclude that the use of recirculation ditches in salt marsh health.Washington,DC.282 pp.RA639 E581. management will result in effective mosquito control and less Provost, M. W. 1977. Source reduction in salt-marsh mosquito environmental impact than the use of insecticides. control:past and future.Mosq.News 37:689-698. Resh,V. H., and S. S. Balling. 1979. Ecological impact of mosquito control recirculation ditches on San Francisco Bay marshlands: Acknowledgments preliminary considerations and experimental design. Proc. Calif. Mosq.Vector Contr.Assoc.47:72-78. NVe thank M.A.Barnby,J.N.Collins,and the personnel of Rosenberg, D. M., V. H. Resh,S. S. Balling, M. A. Barnby,J. N. the California Mosquito Vector and Control Association, Collins, D. V. Durbin,T.S. Flynn, D. D. Hart,G.A. Lamberti, Coastal Region. Support for this project was provided by the E. P. N4cElravy,J. R. Wood,T. E. Blank, D. M. Schultz, D. L. University of California Mosquito Research Funds. Marrin, and D. G. Price. 1981. Recent trends in environmental impact assessment.Can.J. Fish.Aquat.Sci.38:591-624. '�-Teleford,A. D.,and J.D.Rucker. 1973.Successful source reduction Literature Cited on tidal salt marshes. Proc. Calif. Mosq. Vector Contr. Assoc. 41:100. Balling,S. S., and V. H. Resh. In press. The influence of mosquito control recirculation ditches on plant biomass, production, and composition in two San Francisco Bay salt marshes. Estuarine Coastal Shelf Sci. Balling,S.S.,and V. H. Resh. 1982.Arthropod community response to mosquito control recirculation ditches in San Francisco Bay salt marshes.F.nviron.Entomol. 11:801-808. ' Balling, S. S., T. Stoehr, and V. H. Resh. 1980. The effects of mosquito control recirculation ditches on the fish community of a San Francisco Bay salt marsh.Calif. Fish Carne 66:25-34. Barnby, M. A., and V. H. Resh. 1980. Distribution of arthropod ' populations in relation to mosquito control recirculation ditches and natural channels in the Petaluma salt marsh of San Francisco Bay. Proc.Calif.Mosq.Vector Contr.Assoc.49:100-102. Daiber,F.C. 1974.Salt marsh plants and future coastal salt marshes in relation to animals. Pages 475-508 in R.J.Reimold and W.H. Queen, eds., Ecology of halophytes. Academic Press, Inc., New York,NY.605 pp. Edwards,C.A. 1973.Environmental pollution by pesticides.Plenum Press,London.542 pp. Hansen,J. A., F. H. Lesser, R. W. Lombardi,J. K. Shisler,and P. Slavin. 1976.The economics of marsh water management—a New Jersey view. Proc.N.J.Mosq. Exterm.Assoc.63:77-81. Hawkes, H. A. 1979. Invertebrates as indicators of river water IMENNOW Reprinted from ESTUARINE COASTAL ' AN SHELF SCIENCE ACADEMIC PRESS London Orlando San Diego New York Toronto Montreal Sydney Tokyo Published by Academic Press Inc. (London) Limited in association with the Estuarine and Brackish-water Sciences Association lnstrucuUns LU 1-1UMUrs Aquatic Mac roinvertebrate Communities of Natural and Ditched Potholes in a San (1) Estuarine, Coastal and Shelf Science is an international, multidisciplinary journal devoted to the analysis of biological, chemical and physical phenomena occurring in Francisco Bay Salt Marsh waters from the outer edge of the continental shelf to the upper limits of the tidal zone. The journal features original papers from such disciplines as zoology, botany, geology, sedimentology, physical oceanography, numerical models and chemical processes. Papers include analysis of species distribution in relation to varying environments;waste disposal, groundwater runoff, estuarine and fjord circulation patterns, physical Mark A.Barnby,Joshua N. Collins and Vincent H.Resh oceanography and meteorological forcing of semi-enclosed and continental shelf water Division of Entomology and Parasitology,University of California,Berkeley, masses,wave processes and sediment movements. CA 94720,U.S.A. (2) Submission of manuscripts.All manuscripts are to be submitted in English and in the Received 17 December 1983 and in revised form 18 May 1984 first instance must be sent to one of the three co-editors. All papers concerned with life sciences should preferably be sent to Professor E. Naylor, School of Animal Biology, Keywords: salt marshes; salt University College of North Wales, Bangor, Gwynedd, North Wales, U.K., or alter- pans; invertebrata; macrobenthos; biomass; diversity;San Francisco Bay natively, Dr M. Grant Gross, Chesapeake Bay Institute, The-johns Hopkins University, Baltimore, Maryland, 21218, U.S.A. Papers primarily concerned with marine physics and earth sciences should be sent to Dr Nicholas C.Flemming,Institute of Oceanographic Differences o April to community structure and composition were Sciences Wormle Godalmin Surrey, though papers on sediments or chemistry examined from April control to March natural in three potholes that had been y' g' U.K.,' g p p y ditched for mosquito control and three natural(i.e.unditched)potholes,which may also be sent to Dr Grant Gross. Papers submitted to Estuarine, Coastal and Shelf are located in a San Francisco Bay, California, U.S.A. salt marsh. Measure- Science should preferably be less than 14 printed pages in length, equivalent to 10 000 ments of incipient tidal flooding into potholes (i.e. pothole inundation words without diagrams, or the equivalent in words and diagrams. Major articles up to threshold) indicated that these sites comprise a gradient of tidal influences. 15 000 words or equivalent will be accepted at the discretion of the Editors, but there Exponential decreases in the frequency and duration of tidal inundation may be a delay in publication of long papers. There are sections for short notes and corresponded to linear increases in inundation threshold. Since ditched studysites had low thresholds they tended to be more uniformly and regularly observations,book reviews,and correspondence. influenced by tides, were less saline, had less variable temperature regimens, 3 Preparation o typescripts. Typescripts should be submitted in duplicate,using one and supported less filamentous algae than natural potholes.Habitat conditions ( ) p f p g were generally more similar among ditched than unditched potholes, but side only of the paper. Typing should be double spaced throughout the text, including environmental conditions were most severe at natural sites near the upper limit tables, figure legends and reference lists, with a margin of 4 cm on each side. Number of the inundation threshold gradient,where some potholes desiccate during the consecutively all pages, including title page, abstract, text, references, legends and dry season each year. tables. Differences in macroinvertebrate communities corresponded to differences in habitat conditions. Species richness and diversity (Simpson's Index) were (4) Keywords. Up to 8 subject-defining Keywords are allocated to each paper immedi- generally highest near the middle of the inundation threshold gradient,which is ately preceding the abstract. Authors should select preferred Keywords from the list a pattern predicted by the Intermediate Disturbance Hypothesis. Analysis of published in Issue 5 (2), 1977, pp. i-xl and submit them with the Ms if possible. faunal composition using discriminant functions indicated more similarity among potholes located at the lowest positions of the inundation gradient than Keywords should be arranged in order of importance,with the geographical or sea area among potholes with intermediate thresholds. Since ditching lowers the inun- always last. dation thresholds of potholes, it reduces species richness and diversity, while increasing faunal similarity.As a result,extensive ditching to control salt marsh (5) Illustrations.These include figures and plates.Legends for these should be typed in mosquitoes can reduce the overall complexity of lentic macroinvertebrate numerical order on a separate sheet, one for figures and one for plates. Illustrations communities. should be designed with the size of the journal page and column in mind. Each illus- tration should be identified by the name of the author and its number,and its top should be indicated. Magnification should be Introduction g given by a scale line where appropriate. Unsatis- factory illustrations will be returned to the author. Original illustrations are discarded Tidal salt marshes contain a variety of lentic environments,many of which are breeding following publication unless author has requested their return in advance. sites for mosquitoes. In North American salt marshes, man-made mosquito control Maps,line drawings a�i diagrams should be prepared with India ink on white drawing ditches have been used extensively to increase tidal flux in habitats where salt marsh paper, tracing paper,or tracing linen. Several drawings grouped on a page as one figure mosquitoes oviposit,or to drain such habitats,and thereby create unfavorable conditions are distinguished as(a),(b),(c),etc. Figures which must be printed larger than page size for the survival of mosquito eggs and larvae (Smith, 1904; Resh & Balling, 1983a). In 331 0272-7714,85/030331+17$03.00/0 ©1985 Academic Press Inc.(London)Limited some salt marshes, ditches might also allow predatory fish to gain access to habitats 122o 30-W containing mosquito larvae(Connell, 1940;Balling et al., 1980). Very little is known about the effects of ditches on non-target macroinvertebrate species that coexist with salt marsh mosquitoes. Greenstone(1983) who studied preda- San Z tion of lentic invertebrates by the wolf spider Pardosa ramulosa(McCook)in a salt marsh Fron CiscoeaY near San Francisco Bay, California, stated that ditches result in a de au erate insect P P Mospwfo:onrrol onch fauna, because ditches increase the flushing action of the tides. In contrast, Resh & sf ortler cnonnel � � Balling (1983b) indicated that ditches in San Francisco Bay Area salt marshes increase IO kmkm 2na arse*Cho nnel�' Fong • habitat for at least one lentic insect species, the water boatman Trichocorixa reticulata i;:•'D3 "SO r . (Gu6rin-Meneville). Studies of the effects of mosquito control ditches on aquatic macroinvertebrate D2,•,a,,. populations and communities may be essential for a general understanding of salt marsh ecology, since lentic habitats and mosquito control ditches are prominent hydrologic SNdy features of most North American salt marshes. Also, ditches are known to influence 3 :Nz other biotic components of the salt marsh ecosystem. For example, in salt marshes A r N around San Francisco Bay,ditching has been shown to affect the population density and Eff community structure of terrestrial invertebrates(Barnby&Resh, 1980;Balling&Resh, 1982), the community structure of terrestrial plants (Balling & Resh, 1983), the abundance of a resident song sparrow(Collins &Resh, 1985), and both the population ,Tde ouge� density and species richness of estuarine fish(Balling et al., 1980).Therefore,in order to provide information about the response of lentic macroinvertebrates to ditching, we - I km designed a study to compare macroinvertebrate community structure in ditched and o natural(i.e.unditChed)potholes. Figure I. Location of study area,six main study sites(DI—D3,NI—N3),five highest threshold sites(HS),and tide gauge.Examples of ponds,mosquito control ditches,and natural tidal channels of different orders are also indicted. Materials and methods Study area River cover the marsh for consecutive tidal cycles. However,no such flooding occurred during our sampling period,a year in which rainfall was well below average. Petaluma Marsh is a 1145 ha salt marsh located along the Petaluma River, 10 km north of The marsh surface is principally characterized by two types of lentic habitats,ponds San Francisco Bay, California (Figure 1). Overall, the marsh surface is a flat landscape and potholes.Ponds are relatively large basins surrounded by chronically saturated peat that approximately corresponds to the mean height of the higher high tides (MHHW). soil at the headwater areas of drainage systems. Ponds generally do not produce The marsh flora is dominated by pickleweed, Salicornia virginica L., which tends to mosquitoes and seldom are ditched.Potholes i.e. the channel pans of Ya ( P pp et al., 1917) monopolize salt marsh surfaces at elevations near the MHHW tidal datum(Hinde, 1954; are relatively small bodies of water and are remnants of first-order tidal channels.Under Atwater et al., 1979). The elevational succession of plant zones typical of other,higher natural conditions, some potholes receive tidal water via subterranean gradient salt marshes is not evident at Petaluma Marsh,except along its largest sloughs represent the final stage of channel senility. Other Ports, which and immediate periphery. The marsh was extensive) ditched b the M- Sonoma—Sonoma d , generally older potholes no longer P P Y• Y Y contain ports and receive tidal water only during inundation of the surrounding marsh Mosquito Abatement District over a seven-year period,beginning in 1969. surface. These older potholes constitute most of the breeding habitat for salt marsh The water levels of lentic habitats in the marsh are affected by rainfall, a mixed tidal mosquitoes. Consequently,most of the older potholes in Petaluma Marsh are connected pattern (Marmer, 1951), and seasonal river discharge. In northern California, the wet by mosquito control ditches to second-or higher-order natural tidal waterways (Figure season typically lasts from November through April. However, during our sampling Y ( g YP Y g P � g P g 1). The following analysis of ditch effects involves only comparisons among older year,92% of the rainfall in the marsh occurred from January through June. Therefore, potholes. P we have designated these six months as the wet season. Since elevations of the marsh surface differ only slightly from MHHW, only the Study sites highest tides of the biweekly springtide series can inundate the marsh entirely.Although Our studies were concentrated among three ditched and three natural potholes, which the highest annual tines generally occur in January and July, the marsh is frequently are collectively referred to as the main study sites. In addition to these sites,we routinely inundated during June,August,and December. Therefore, the lentic habitats are most examined five other natural potholes that are among the highest elevation lentic environ- likely to desiccate during October and early November,when both tidal inundation and ments in the marsh.All eleven sites are close to one another and are similar in size,rela- rainfall are least likely to occur. During some winters, flood waters from the Petaluma tive to the maximum size range for older potholes in the study area(Figure 1).However, 100 Hs TABLE 1. Characteristics of the tidal regimens of the main ditched (D1-D3), main N3 natural(NI-N3),and highest threshold(HS)study sites,based upon continuous tidal N2 measurements for the duration of the sampling year(April 1980 to March 1981) Threshold relative No.of inundations Total hours of 80 _ ------------- - -- - - Site to MHHW cm C NI(MHHW) ( ) per year inundation per year O `o ' D 1 —15 328 1170 _> D3 i D2 —14 318 1090 D3 —5 261 780 N I 60 1 02 N2 +10 98 245 ° N3 +15 56 110 o D2 HS +20 41 70 y � DI � N , N 40 L ; All of our study sites supported floating, aquatic vegetation, at least during part of t our sampling year. This cover was dominated by green algae, including Enteromorpha ° clathrata (Roth) Grev., Ulothrix fiacca (Dillw.) Thur., and Ulva sp. Some sites also 20 supported small amounts of widgeon grass, Ruppia maritima L., which was the only macrophyte among our study sites. I Environmental data Preliminary field work was begun in November 1979; quantitative data were collected o 1 from April 1980 to March 1981. Water salinity within each study site was measured DI D2 D3 NI N2 N3 HS weekly with a refractometer.Weekly values for the duration and frequency of tidal inun- -ico -50 0 +50 Elevation relative to MHHW dation were derived from the continuous record of the tide gauge.Visual estimates of the Figure 2. Cumulative frequency distribution for thhee high tides at the center of percent aquatic plant cover at each main site were made weekly. In situ max/min ther- Petaluma Marsh,relative to the inundation thresholds of the study sites,based upon . mometers were used to measure weekly temperature extremes at the main sites. In the continuous empirical tidal measurements for the duration of the sampling year(April summer of 1980,thermographs were installed at two adjacent potholes,one ditched and tide to March I For example,the figure shows that about 30°-0 of all the high tides inundated allll three of the ditched sites. one natural, to determine the effects of tidal inundation on pothole temperature. The thermographs were used over a complete lunar cycle(10 August to 10 September 1980). Biological data following an inundating tide,ditched sites were shallower than natural sites(2.5-7.5 cm During the year of data collection, three 180-cm2 compared with 20-30 cm). samples were taken monthly at each main site. On two of the twelve sampling dates, samples were taken at high tide; at all Empirical measurements of the times and heights of tides in a slough near the study other times samples were taken during slack low tide. All samples were taken at the sites(Figure 1),when combined with records of exact moments of site inundation,indi- centers of randomly selected quadrats,and no quadrat was selected more than once. cated that each study site has a unique inundation threshold. Each threshold represents In sampling, a 1-m long, 15 25-cm diameter PVC pipe was thrust 5 cm into the both the actual elevation of a site and the time necessary for tidal water to travel over the pothole substrate, then removed by covering the pipe bottom and lifting upward. Since marsh surface or through a ditch. Therefore,two sites that are at the same elevation but we had established that the bottom 4 cm of a sample were composed of anoxic substrate at different distances from their common source of tidal water will have different inun- that contained no living organisms,only the water and the uppermost 1 cm of substrate dation thresholds.In order of increasing threshold,the study sites were labelled D 1,D2, were retained for processing. D3,N1,N2,N3,and HS,with the letters D and N designating ditched and natural main Each sample was washed consecutively through sieves with 2 mm(no. 10), 1 mm(no. sites,respectively,and HS designating the highest threshold sites(Figure 1).The lower 18),and 500 µ(no.35 three potholes(i.e.D1—D3)were ditched in 1976. )pore sizes.The washed material was then floated on saturated salt Tidal re tmens va solution to facilitate the sorting of specimens. The biomass of a sample was determined g ry predictably along the inundation threshold gradient. For by oven-drying to constant weight at 105°C example,thresholds for the ditched sites represent positions near mid-tidal range,where g , prior to weighing, samples were cooled g � with dehydrated air. changes in tidal regimen per unit change in elevation are greatest(Figure 2). However, about 30% of all thL"high tides inundated all of the ditched sites. In contrast, most Analysis thresholds for the natural sites correspond to positions above the MHHW tidal plane, Simple linear regression was used to measure how each environmental factor varied where tidal inundation is relatively infrequent and short in duration(Figure 2,Table 1). along the inundation threshold gradient. We used two-way analysis of variance to test /5 25 2 2 (o) (b) h2•` � • •2 z `o- 60 • • tiE 20 2 r=-0.87 z`\�2. •2 • N p �� • g• 3 • • • /• • • 0 15 '� \� 2\2 3 • • • • • i • .' `2� • • 2\ 3 .0 45 • ��. 3\ �0 2 2 r=-D•72 • 2 2 2 p • • i\ q V • �- 2 2 3 3 .�i d • • • • 2 3 ' 30 • • . • 5 2 2� z ° • • z s �1 2 2 a • 2 E • • =051 • r=0.64 DI D2 D3 NI N2 N3 HS DI D2 02 NI N2 N3 HS t 15 • • • 2= -15-14 -5 O +10 +15 +20 -15-14 -5 0 +10 +15 +20 0 • Site inundation threshold relative to MHHW (cm) •• • 2• • Figure 3. Relationships between inundation threshold and weekly temperature range • • for(a)wet and(b)dry seasons.For the wet season,dashed line represents weeks with at 01 01 D2 D3 NI N2 N3 HS DI D2 D2 NI N2 N3 HS least 1.25 cm rainfall;solid line represents weeks with less rainfall. -15-14 -5 0 +10 +15 +20 -15-14 -5 0 +10 +15 +20 Site inundation threshold relative to MHHW(cm) Figure 4. Relationships between inundation threshold and variability of temperature the hypotheses that neither seasonal biomass nor species diversity (Simpson's Index, range for(a)wet and(b)dry seasons.Variability is reported as the monthly coefficient sensu Routledge, 1979)differed between the ditched and the natural potholes. of variation calculated from weekly temperature ranges. Linear discriminant analysis (Klecka, 1975) was used to measure the similarity of physical conditions and faunal composition among the main sites, and to determine if ditched than the natural study sites. Also, when tides recede from the marsh surface, any species assemblages were indicative of particular inundation thresholds or pothole ditched potholes are nearly drained,and the remaining shallow water rapidly exchanges conditions. Discriminant analysis reduced each data case (i.e. a set of date- and site- , heat with the atmosphere. Thus, both frequent inundation and changes in water level specific measurements of physical parameters or population densities) to a single can cause ditched potholes to have broad temperature ranges during short(i.e. 1 week) summary index(i.e. the discriminant score).Each case was then reassigned,according to time periods. its score, to one of the six main sites, with the discriminant functions minimizing the When longer periods of time(i.e. 1 month)were considered,the variability of weekly probability of incorrectly reassigning data.The absolute magnitudes of the discriminant temperature range was positively correlated with inundation threshold for both the wet function coefficients, which weight each variable in a case, were used to identify the and dry seasons [Figure 4(a), (b), respectively]. This is because regular inundation species or physical parameters that were most important for correctly classifying cases. reduces the influence of atmospheric temperatures, which vary more than the The mean discriminant score(i.e. the centroid)for each site was plotted,using the dis- temperatures of the tides. criminant functions to calculate Cartesian coordinates. Physical and faunal similarities Among all the study sites,salinity was lower and more uniform in the wet season than among the sites were then inferred from the relative positions of the centroids. in the dry season[Figure 5(a),(b)],because wintertime increases in rainfall and river dis- charge reduced salinities throughout the marsh. During the dry season, the more fre- Results and discussion quent tidal flushing in ditched potholes generally prevented salt accumulation, whereas The environment of a pothole in natural potholes low rates of flushing allowed salts to concentrate. Among potholes with similar tidal regimens,those covered with thick algal mats had higher salinities than The physical data indicate that the environment of a pothole varies according to its those lacking such cover. For example,the scant algal cover in pothole N1 [Figure 6(a)] inundation threshold. For example, weekly pothole temperature range descreased with was probably responsible for its low salinities relative to D3,a site which had a slightly increasing threshold for the wet and dry seasons [Figure 3(a),(b), respectively]. This is lower inundation threshold but much greater algal cover[Figure 6(b)]. Since a filament- because temperatures in ditched potholes are regularly influenced by the tides, which ous algal mat increases pothole surface area, the mat can also increase evaporative water both import and export heat. Night-time flood tides,which in general are warm relative loss, and thus increase pothole salinity. At Petaluma Marsh, evaporative losses due to to the soil and air,and the relatively cool daytime flood tides exchange less heat with the algal mats might be accelerated by afternoon winds that reduce the water vapor pressure air and soil while traveling through a full ditch than when traveling as a thin sheet of at the marsh surface. This influence of algae on salinity may be responsible for the low, water over the mars surface (Felton, 1978). As a result, temperature differences but significant positive correlation between inundation threshold and weekly maximum between water already in a pothole and the incoming tidal water are greater for the salinity for the dry season (r=0-25; P<0.01). Bleakney&Meyer(1979)also found that 140 00 N2 ....... .......... I �1 75 120 �. 1 ! 1 50 \ ' 100 HS I N3 J j 1 1 25 j V^ 60 /� / / I N3 \. u NI 100 20 �� _�.vi 75LD2 3, J� — r - N 50 \V/ ^ / V60 (b) 25 V 50 /t 1 1 II May Jun Sep Nov Jon Mar 'Y/11 �t 1 / l l�\ s tes.re 6igu .Percent algal cover of water surface for(a)natural and(b)ditched main study 40 �J D3 /D2 30 /.•' l r TABLE 2.Mean values±S.D.of total macroinvertebrate community biomass(g m-2) / D 1 `� /J for natural and ditched potholes in the wet and dry seasons 20 J 10 — Natural Ditched Wet season 0.061±0.041 0 056±0 043 May Jul Sep Nov Jon Mar Dry season 0.045±0.045 0 043±0 032 Figure 5. Seasonal patterns of change in salinity for (a) natural sites including the highest threshold sites(HS),and(b)ditched study sites. thresholds, infrequent tidal inundation can result in very high salinities and habitat tidal regimen, algal cover, evaporation, and precipitation caused fluctuations in pool desiccation. Although temperatures can be extreme for low threshold potholes,thermal salinities in a salt marsh located near the Bay of Fundy,Nova Scotia. In contrast,Ward regimens are more variable for potholes with high thresholds."Therefore, any aquatic &FitzGerald(1983a)found that temperature in a Quebec salt marsh was the major fac- macroinvertebrate populations living in high threshold potholes will be subject to for controlling pool salinities, although algal cover did not differ among the pools they environmental conditions that involve very high salinities, insufficient moisture, and studied. irregular and unpredictable changes. Percent algal cover was positively correlated with inundation threshold, especially in the dry season(r=0.60;P<0.01).However,algal cover was highly variable,even among Community parameters study sites with similar thresholds. Although our data do not indicate reasons for the Biomass variable distribution of algae among the natural sites,some mechanisms for cover reduc- Wet season community biomass was significantly higher than dry season biomass tion at potholes with low thresholds can be inferred. For example, relatively high (P=0.05)in both the natural and ditched sites,whereas differences in biomass between frequencies of tidal flushing may have disrupted the algal mats and caused their export. ditched and natural sites were not significant for either season (P=0.71;Table 2). The A similar mechanism was suggested for the lack of an established algal cover in a low higher invertebrate biomass during the wet season may have resulted from increased elevation pool in a Quebec salt marsh(Ward&FitzGerald, 1983a). food resources. For example, we observed that most algal mats began decomposing in Our analysis of abiotic parameters suggests that high threshold potholes are Leroy winter,when detritivores dominated the pothole fauna. Similarly, Cameron(1972) environmentally severe habitats for macroinvertebrates. In potholes with high reported that organic debris increased during wintertime in a nearby salt marsh,and this material provided a large tood source for invertebrate detrltivores. we also observed that TABLE 3.Fauna collected at all study sites during wet and dry seasons in Petaluma Salt Marsh.For the natu- macroinvertebrates did not feed on viable algal mats, and infer that the healthy algal ral and ditched main sites,counts are totals per season.Only presence(+)or absence of species is indicated mats that occurred during summer were more important as microhabitat than as food. for the highest threshold sites Natural Ditched Highest Species richness The species richness of the aquatic macroinvertebrate fauna of Petaluma Marsh is wet dry wet dry wet dry apparently higher than that reported for other salt marshes. Nicol (1935) collected 13 species of insects in an English salt marsh; Campbell & Denno (1978) collected 20 Polychaeta sp. 8 23 13 6 species of insects in a New Jersey salt marsh;Kelts(1979)collected 19 species of insects Oligocheata in a New Hampshire salt marsh;and Ward&FitzGerald(1983a)collected 12 species of Lumbriculus lineatus Muller 55 113 12 58 insects in a Quebec salt marsh. At Petaluma Marsh we collected 60 166 specimens Paranais litoralis(Muller) 11 192 7287 20 716 5982 representing 32 taxa of macroinvertebrates, of which 24 taxa were insects (Table 3). (these counts include Tubificoides nethoides(Brinkhurst)and two However,results from these studies are not strictly comparable,since different sampling undescribed species of methods were used. Our study also revealed a much richer insect fauna for Petaluma Rhyacodrilinae,all of which are rare Marsh than previously described by Greenstone(1978),but he did not actually sample taxa in samples) the pothole invertebrates. In addition, the collection of 8322 insect specimens that Crustacea comprised 18 taxa from our three ditched stud sites disagrees with the assertion b Tanais vanis Miller 12 5 23 5 p Y g Y Anisogammarus confervicolus Greenstone (1983) that ditched potholes in Petaluma Marsh are devoid of aquatic (Stimpson) 1552 196 198 35 insects. Insecta Species richness was always higher for sites N1 through N3 than for either the ditched Hemiptera or the highest elevation sites (Figure 7). This pattern may be a function of changes in Trichocorixa reticulata either the disturbance rate or habitat severity along the inundation threshold gradient. (Guerin-Meneville) 867 1957 1201 5859 + + Diptera Among low threshold potholes,tidal disturbances(i.e. sediment transport,algal export, Chironomus sp. 83 0 0 0 and changes in water level,salinity,and temperature)are frequent,whereas severe con- Cricotopus sp. 101 0 8 o ditions(i.e. very high salinities and desiccation)are most probable among potholes with Hydrobaenus sp. 3 0 1 3 the hi hest thresholds. According to the `Intermediate Disturbance Hypothesis' ' . Dasyhela sp. 43 21 73 21 a g g YP Psychoda salicornia Quate 3 2 252 138 f (Connell, 1978),species richness is greatest where rates of habitat disturbance or habitat Aedes dorsalis(Meigen) 4 0 0 0 + severity are intermediate. In our study,plots of richness versus inundation threshold for Aedes squamiger(Coquillett) 2 0 0 0 + both the wet and dry seasons [Figure 8(a), (b)] resemble the relationship predicted by _ Dolichopus sp. 35 95 45 34 Eristalis tenax Linnaeus 9 6 1 1 + + Connell (1978). Other studies have shown that marine invertebrate species diversity is Tabanus laticeps Hine 0 0 0 1 greatest where disturbance rates are not extreme(e.g.Levin&Paine, 1974;Sousa, 1979). Odontomyia sp. 41 16 4 1 Chiromyzinae sp. 1 1 2 0 Ephydra millbrae Jones 242 344 253 223 + + Lamproscatella muria Matis 32 16 5 19 Species diversity Scatella stagnalis Fallen 0 1 1 0 During both the wet and dry seasons, species diversity was significantly higher for the Paracoenia bisetosa(Coquillett) 0 q 3 0 natural than the ditched potholes(P<0.01);however,no significant seasonal differences Hydrelliagriseola(Fallen) 1 1 0 0 were found (P=0.81; Table 4). The patterns of species diversity among our study sites C p. 0 1 40 3 Cyclorrclorrhapha sp. 5 3 1 0 reflected differences in abundances of the most common taxa, which corresponded to Coleoptera environmental differences along the threshold gradient. For example,the density of the Enochrus diffusus(Le Conte) 236 147 87 39 most common invertebrate, the oligochaete Paranais litoralis (Muller) (Figure 9), was Berosus punctatissimus Le Conte 16 0 0 0 both directly and indirectly influenced by environmental factors. In potholes D 1 and Tropisternus salsamentus Fall 0 3 0 0 D2,the amount of filamentous algae was insufficient to serve as refuge for P. litoralis.As Ochthebius rectus Le Conte 13 2 3 0 a result, P. litoralis was probably consumed in large numbers by the second most com- mon macroinvertebrate, the water boatman T. reticulata, which is at least a facultative of T. reticulata were never observed within these mats. Among potholes with higher consumer of small animals(Carpelan, 1957;Davis, 1966;Cox, 1969).In potholes D3 and thresholds, harsh conditions (i.e. high salinity and frequent desiccation) may have N1, however, large4iumbers of P. litoralis were probably able to avoid predation by directly limited the density of P. litoralis. For example,low numbers of P. litoralis were inhabiting filamentous algae. This conclusion is based on repeated observations that sampled in pothole N3,although filamentous algae were abundant and T. reticulata was algal mats typically contained large numbers of P. litoralis,whereas nymphs and adults scarce. 10 103 (a) N3 (d) D3 0 8 N a) 02 0 1 ■� a I0 / • l •—•—� .. l— ��� —• 0 6 0 p •.............. o i z 4 HS �. ��� E May Jul Sep Nov Jan Mar 102 • • /■�•�■�� Figure 7.Temporal patterns of species richness for ditched(D)and natural(N)main a I O • ti_ _a_ _ \ • study sites and highest threshold sites(HS). c 103 (C) NI (f) pi 10, 6—May Jul Sep Nov Jan Mar May Jul Sep Nov Jan Mar Figure 9. Temporal patterns of the abundance (loglo) of P. litoralis (0-0), T. 4 reticulata(■--■),and A.confervicolus(♦ •••♦),at the main study sites. Natural sites are represented by graphs(a){c);ditched sites by graphs(dHf). 2 Two environmental factors probably allowed populations of T. reticulata to attain very high densities, such as those which occurred in the two lowest threshold ditched O High sites and in the lowest threshold natural site(i.e. D1,D2,N1; Figure 9). First,frequent inundation reduced the risk of habitat desiccation and the consequential stranding of 6 - immature, wingless water boatmen (Balling & Resh, 1984). Second, since these three potholes contained relatively small amounts of floating algal cover{Figure 6(a),(b)],they .. tow were probably more intensively colonized by aerial adult water boatmen.This is because Frequent mfreQoent adults that alight on algae tend to explore it briefly,then take flight, whereas those that 8 (b) Dislurponces e land in open water tend to remain. Increased water salinities were apparenty not a factor in reducing the numbers of T. 6 reticulata in potholes with high inundation thresholds, since dense populations have 4 been observed in high threshold potholes that were devoid of algal cover and where water salinities were two to four times as concentrated as seawater.Also,Carpelan(1957) found the highest population densities of this species in very saline (i.e. 6391oo) salt 2 evaporation ponds located adjacent to southern San Francisco Bay. The spatial and temporal occurrence of the third most common invertebrate, the DI D2 D3 N I N2 N3 HS amphipod Anisogammarus confervicolus (Stimpson) (Figure 9), might also have been Figure 8.Relationship between species richness and environmental severity or rate of directly affected by conditions of algal cover. That is, populations of A. confervicolus habitat disturbance as represented by inundation threshold(i.e.relative positions along were most abundant during the wet season, and were essentially restricted to high the abscissa reflect height above MHHW)for(a)wet and dry seasons.Means and threshold potholes containing large amounts of deteriorating filamentous algae. Since A. error bars for the highest threshold sites are based upon weeklkl y collections. confervicolus is a detritivore, the decomposing algal mats probably served as a food TABLE 4. Mean values±l S.D. of total macroinvertebrate community diversity resource. A similar relationship between occurrence of A. confervicolus and filamentous (Simpson's index)for natural and ditched potholes in the wet and dry seasons algae was observed by Carpelan (1957) in salt evaporation ponds near southern San Francisco Bay. Natural Ditched In the above discussion,we suggest that many of the differences in macroinvertebrate community structure that we observed among potholes in Petaluma Marsh were due to Wet;a son 1.04±0.51 0.70±0.32 differences in abiotic factors and algal cover. This is in contrast to Campbell & Denno Dry season 1 12±0 59 0.66±0.37 (1978), who ascribed spatial differences in invertebrate community structure among unditched potholes in a New Jersey salt marsh to predation by birds and fish. However, (a) (b) a ' NI o o (o) (b) NJ3. c c NI o DI D2 N3 a02 N3 a .D2 N3 .D3 c j N2 ° N2 :Ev DI `v2 �•h •D3 DI c DI • aQ D3 0 o D2 r 4i • V N2 NI Monthly density of Monthly density of Monthly inundation frequency E. Diffusus Doiichopus and E.tenox Figure 10. Plots of(a)wet and (b)dry season main site discriminations based upon Figure 11. Plots of(a) wet and (b) dry season main site discriminations based upon environmental parameters.Each site is represented by its centroid(see methods).The faunal composition and species density. Each site is represented b most discriminating factors of the first and the second functions are given as labels for P y its centroid(see the abscissa and ordinate,respectively. Distances among centroids parallel to either methods).The more important antaxd rd the first and second discriminating functions are axis indicate absolute differences; the axes do not indicate direction of increase or given t labels for the abscissa and ordinate,respectively.Note that the axes only show absolute differences; the direction of increase or decrease in species density is not decrease in paremeter value. indicated. these salt marsh pools may be less variable as habitats, and therefore might support thresholds (i.e. D3, N1) were distinguished mainly by differences in salinity [Figures invertebrate communities that are less regulated by physical factors than the communi- 10(a),(b)]. The pattern of classification for sites D3 and N1 probably reflects the higher ties in Petaluma Marsh. Signs of bird visitation were rare among our study sites,and we salinities caused by the greater algal cover in site D3 relative to site N1. infer that predation by birds generally did not influence the structure of the macroinvertebrate communities. Furthermore, at Petaluma Marsh the invasion of The fauna potholes by large numbers of fish was apparenty both spatially and temporally uncom- If the macroinvertebrate species assemblages of potholes are indicative of discrete mon, and probably did not affect macroinvertebrate community structure. In fact, we positions along the inundation threshold gradient,then the study sites can be classified observed fewer than 50 fish among our study sites during more than 150 h of reconnais- according to their faunal characteristics,and the pattern of classification(i.e.the relative sance spanning 12 consecutive months. Almost all of these fish were threespine stickle- positions of the centroids in the discriminant function plots)should resemble that based back, Gasterosteus aculeatus L., which apparently only invade potholes during tidal upon the environmental features. c. inundation and feed almost exclusively on microcrustacea (Balling, unpublished data): Using population densities of all species as variables,72% and 67% of the cases were In addition,caged experiments in a salt marsh pool in Quebec indicated that G.aculeatus classified correctly for the wet and dry seasons, respectively. Again, this indicates suc- had no measurable impact on the macroinvertebrate community (Ward & FitzGerald, cessful classification relative to the 16% chance(1 in 6)of randomly assigning data cases 1983b). to the correct study sites.Also,the centroids for the sites generally were plotted accord- ing to their position along the threshold gradient [Figure 11(a), (b)]. For both seasons, The environment Environmental and faunal similarity the centroids for the ditched potholes were grouped together and the centroid for the next higher pothole(i.e.N1)was plotted nearby.The centroids for the two sites with the Based upon environmental factors, the discriminant functions correctly classified 89% highest thresholds(i.e.N2,N3)were plotted apart from each other and the rest. and 86% of the data cases for the wet and the dry seasons, respectively. This indicates These results indicate that ditched and natural potholes with different inundation successful classification relative to the 16% chance (1 in 6) of randomly assigning the thresholds below MHHW (e.g. DI—NI) support similar macroinvertebrate faunas, data cases to the correct study sites. Incorrect classification of cases occurred mainly whereas potholes with different thresholds above MHHW(e.g. N2,N3)support faunas among potholes with similar inundation thresholds. that are more distinct. Furthermore, since physical conditions were similar for potholes The discriminant analysis based upon environmental factors indicated that each main N2 and N3[i.e. based upon physical factor centroids;Figure 10(a),(b)],the distinctive- site was environmentally unique, but that those sites that have the most similar ness of their faunas suggests that slight differences in threshold (e.g. 5 cm) above inundation thresholds were also most similar with regard to temperature,tidal regimen, MHHW can result in relatively large differences in species composition and population salinity, and percent plant cover. For example, although the percent correct classifica- density. tion was always high, the centroids for potholes D1 and D2 were consistently plotted Rare taxa, found primarily at sites Ni—N3, were important in distinguishing these together, as were centroids for potholes N2 and N3 [Figures 10(a), (b)]. Although the sites from the ditched sites. For the wet season [Figure 11(a)], the most important dis- centroids for the two sites with intermediate thresholds(i.e. D3,N1)were plotted apart criminators were Enochrus diffusus (Le Conte) larvae and adults, and larvae of the from one another, they were consistently plotted between the centroids for the higher chironomid genera Cricotopus and Chironomus. For the dry season [Figure 11(b)], the and lower threshold p sites. These four sites (i.e. D1, D2, N2, N3) were primarily dis- most important taxa were Dolicho us larvae larvae of the rat-tailed mag got Eristalis tinguished by differences in inundation threshold, whereas the sites with intermediate tenax L.,and larvae of E.diffusus. - --�---� nailing,S. S., Stoehr,T.&Resh,V.H. 1980 The effects of mosquito control recirculation ditches on the fish community of a San Francisco salt marsh. o Cali Barnb f rnpo Fish p and Game 66,25- q Although the surface of Petaluma Marsh approximately corresponds to the mean height y,M.A. &Resh,V.H. 1980 Distribution of arthro d populations in relationon to mosquito control of the higher high tides (MHHW), an elevational gradient from at least 15 cm below recirculation ditches and natural channels in the Petaluma Salt Marsh of San Francisco Bay. Proceedings of the California Mosquito and Vector Control Association 48,100-102. MHHW to 20 cm above the tidal datum is represented by the inundation thresholds of Bleakney, J. S. & Meyer, K. B. 1979 Observations on saltmarsh pools, Minas Basin, Nova Scotia, potholes. Both the frequency and duration of tidal inundation among salt marsh lentic 1965-1977.Proceedings of the Nova Scotia Institute of Science 29,353-371. Cameron,G.N.1972 Analysis of insect trophic diversity in two salt marsh communities.Ecology 53,58-73. environments decrease exponentially with linear increases in inundation threshold. Campbell, B. C. & Denno, R. F. 1978 The structure of the aquatic insect community associated with However, habitat conditions are most variable among potholes with intermediate intertidal pools on a New Jersey salt marsh.Ecological Entomology 3,181-187. thresholds that approximately correspond to MHHW, where slight differences in Carpelan,L.H. 1957 Hydrobiology of the Alviso salt ponds.Ecology 38,375-390. threshold can result in ecologically significant differences in salinity and moisture. Collins,J. N. & Resh, V. H. 1985 Utilization of natural and man-made habitats by the salt marsh song sparrow,Melospiza melodia samuelis Baird.California Fish and Game(in press). In Petaluma Marsh,macroinvertebrate community structure and faunal composition Connell,J.H. 1978 Diversity in tropical rain forests and coral reefs.Science 199,1302-1310. vary among potholes according to differences in habitat conditions, which are regulated Connell,W.D. 1940 Tidal inundation as a factor limiting the distribution of Aedes spp.in a Delaware salt by the tides.For a given season,species richness is lowest and faunal composition is most marsh.Proceedings of the NewJersey Mosquito Extermination Association 27,166-177. Cox,M.C. 1969 The biology of the euryhaline water boatman Trichocorixa reticulata(Guerin-Meneville) similar among potholes that have very high (i.e. >15 cm above MHHW) inundation (Hemiptera-Corixidae).M.S.Thesis,California State University,San Diego.84 pp. thresholds, and therefore have environmental conditions that tend to be extreme. Davis,C.C. 1966 Notes on the ecology and reproduction of Trichocorixa reticulata in a Jamaican salt-water Among potholes with very low thresholds (i.e. <10 cm below MHHW), habitat con- pool.Ecology 47,850-852. ditions are relatively simple, invariant and not severe consequently, species richness Felton,C. M. Berkeley, The energy budget of a south San Francisco tidal salt marsh.Ph.D.thesis,University Y P ' � 3 q Y� P of California,if ,Berkeley,California.322 pp. and diversity are relatively low, and faunal composition is similar throughout the year. Greenstone, M. H. 1978 The numerical response to prey availability of Pardosa ramulosa (McCook) Among potholes with intermediate thresholds(i.e.near MHHW),significant differences (Araneae:Lycosidae)and its relationship to the role of spiders in the balance ofnature.Symposia of the in habitat conditions correspond to slight differences in threshold Zoological Society of London 42,183-193. . Faunal composition is Greenstone,M. H. 1983 Site-specificity and site tenacity in a wolf spider:A serolo ical diet most variable among these potholes, and species richness and diversity are relatively j Oecologia 56,79-83. 8 ary analysis. high. Hinde, H. P. 1954 Vertical distribution of salt marsh phanerograms in relation to tide levels. Ecological Monographs 24,209-225. When a pothole is ditched, its inundation threshold is lowered,usually from an inter- Kelts, L. J. 1979 Ecology of a tidal marsh corixid, Trichocorixa verticalis (Insects, Hemiptera). mediate position near MHHW, to a new position much below that tidal datum. Conse- Hydrobiologia 64,37-57. Klecka, W. R. 1975 Discriminant analysis. pp. 434-467. In SPSS, Statistical Package for the Social quently, its environmental characteristics and the macroinvertebrate community that it Sciences. Nie, N. Hull, C. Jenkins, J. G., Steinbrenner, J. and Bent, D. H. (eds). 2nd ed., supports becomes less complex and more indicative of a broad range of lower elevation i McGraw-Hill Boo okk Co.,New York, ,675 pp. tidal regimens. Since ditched potholes are more numerous than ponds and natural Levin,S.A.&Paine,R.T. 1974 Disturbance,patch formation and community structure.Proceedings of the potholes combined,a large proportion of the lentic habitats in Petaluma Marsh probably National Academy of Science(U.S.A.)71,2744-7. support macroinvertebrate communities that are now simpler and more alike one Manner, H. A. 1951 Tidal Datum Planes. Special publication no. 135, U.S. Dept. Commerce, U.S. P I Government Printing Office,Washington,D.C. 142 pp. another than they were prior to ditching. Nicol,E.A.T. 1935 The ecology of a salt-marsh.Journal of the Marine Biological Association of the United Kingdom 20,203-261. Resh, V. H. & Balling, S. S. 1983a Ecological impact of mosquito control recirculation ditches on San Acknowledgements i Francisco Bay marshlands: Study conclusions and recommendations. Proceedings of the California Mosquito and Vector Control Association 51,49-53. We thank S. S.Balling for project assistance and R.O.Brinkhurst for oli ocheate identi- Resh, V. H. & Balling, S. S. 19836 Tidal circulation alteration for salt marsh mosquito control. g Environmental Management 7,79-84. fications. Support for this project was provided by University of California Mosquito Routledge, R. D. 1979 Diversity indices: Which ones are admissible?Journal of Theoretical Biology 76, Research Funds. 503-515. - Smith,J.B. 1904 The common mosquitoes of New Jersey.Bulletin of the New York Agricultural Experiment Station 171,1-40. Sousa, W. P. 1979 Disturbance in marine intertidal boulder fields: the nonequilibrium maintenance of References species diversity.Ecology 60, 1225-1239. e W.1979 History, Ward,G.&FitzGerald,G.J. 1983a Macrobenthic abundance and distribution in tidal pools of a Quebec Atwater,B.F.,Conrad,S.G.,Dowden,J.N.,Hedel,C.W.,MacDonald,R.L.&Savage, Y, ) salt marsh.Canadian Journal of Zoology 61,1071-1085. landforms and vegetation of the estuary's tidal marshes, pp. 347-385. In San Francisco Bay: The Ward,G.&FitzGerald,G.J. 1983b Fish predation on the macrobenthos of tidal salt marsh Urbanized Estuary(Conomos,T.J.,ed).Pacific Division,American Association for the Advancement journal of Zoology 61,1358-1361. pools.Canadian of Science,San Francisco,493 pp. j Yapp, R. H., Johns, D. &Jones, O. T. 1917 The salt marshes of the Dovey Estuary. Part II. The salt Balling,S.S.&Resh,V.H. 1982 Arthropod community responses to mosquito control recirculation ditches marshes.Journal of Ecology 5,65-103. in San Francisco Bay salt marshes.Environmental Entomology 11,801-808. Balling,S.S.&Resh,V.H. 1983 The influence of mosquito control recirculation ditches on plant biomass, production, and composition in two San Francisco Bay salt marshes. Estuarine Coastal and She; Science 16,151-161. Balling, S. S. & Resh*%7. H. 1984 Life history variability in the water boatman Trichocorixa reticulata (Hemiptera:Corixidae)in San Francisco Bay salt marsh ponds.Annals of the Entomological Society of America 77,14-19. ENVIRONMENT 4s ,v�7'o . N�fie rt 1wosqui* to ruce Nucc� �tc�ica��c✓s. Killing the tiny pests has gotten so expensive that some governments have started questioning whether the war is worth it. p in Minnesota, relief is on the way for the unofficial State Nuisance. The mosquitoes don't know it, but the swampy summer nights they love will soon be a little sweeter.The state is run- ning out of enthusiasm for meddling in their affairs. That is big news because, over the years, no state has committed itself more heavily than Minnesota to the war against the common pest known as Aedes vexans. With a $10 million annual bud- get,guaranteed to it through a state-man- dated lev y on property perry taxes,Minnesota's Metropolitan Mosquito Control District is the largest entity of its kind in the nation. It destroys mosquitoes in seven BY D O U G L E M O V I counties with an arsenal of chemical and In other places, however, that selling .................................................. job has become much re cult in biological weapons that ranges from the nationwide.According to one estimate,at tough budgetary times.•Connecticut spraying of pesticides to the removal of least 80 percent of the American popula- recently abandoned its entire mosquito old tires from areas where they might lion is currently protected by control dis- control effort; Ohio cut its program by serve as incubators. tricts, which adds up to a roughly Boasting a fleet of 212 vehicles and a million per year publicly funded industry. more than 50 percent two years ago.And staff of 57 full-time and 160 seasonal And Minnesota's is not the only one mosquito problem, therrelia is g owing employees,Minnesota's mosquito fighters funded on rather generous terms. Last skepticism about the cost of the warfare are the unquestioned Green Berets of year, before hard times came unexpect- the MMCD wages. In the view of its mosquito control. The MMCD prides edly to Orange County, California, the loudest critic, state Senator Ted Mon- itself on its state-of-the-art techniques, mosquito control district there was criti- dale, the MMCD is almost as much of a .` such as the use of hormone-laced briquets cited in the local press for its $5 million nuisance as the creatures it combats. "if that interrupt the hatching cycles of mos- budget, its fleet of new trucks equipped you say, `Show me that it works,' ' Mon- quito larvae. In the off-season, the district with cellular phones and its frequent staff dale complains, "the district cannot even runs mosquito awareness campaigns. junkets to conferences in distant places. prove that it provides a significant Few states have made mosquito con- In Fort Myers, Florida, the Lee County lion in the number of mosquitoes in the trol quite so much an article of budgetary Mosquito Control District wages a year- region. The amount of rainfall is still the faith as Minnesota,but quite a few are in round battle against mosquitoes with its primary determinant of that." the business to one extent or another. In own airport and whole fleets of converted Representative Mindy Greiling, Mon- recent years, 12 states have provided Bell and Huey helicopters, all at an dale's fellow critic in the Minnesota money to localities for mosquito control annual cost of more than $8 million.And House, argues that it is time for the state purposes, and most others have control Lee County has no intention of scaling to stop treating mosquito control as a districts operating at county or metropoh- back."If you've truly got a problem,"says "sacred cow." In her view, the MMCD tan levels. All told, there are about 1,300 the mosquito district director, William has been using its ample war chest with programs of one sort or another operating Opp,"the program sells itself." almost no accountability or restraint. In ?.eja Ce"nanylThe Stadf Mader photograph July 1995 GOVERNING 47 Without adequate 1992-93, it spent $7.1 million in cash on mosquito control says MMCD Administrator Jim Stark. new headquarters buildings alone. In Given the current budget climate, 1994, it put $620,000 into helicopter measures, says however, such a stance may be out of rentals. step with the times. With tough choices At the urging of Mondale and Greiling, entomologist Roger D. ahead, even programs much leaner than the legislature enacted a law this year the MMCD can expect to see the budget that effectively allows half the MMCD Moon, `we could easily knife.Legislatures are being forced to ask budget to be siphoned off into a new themselves whether mosquito-borne dis- affordable housing program. The law by get malaria back.' eases are more deserving of limited pub- no means puts MMCD out of business. lic health funds than programs targeting Even at $6.8 million a year (including TB,AIDS,even Lyme disease. some state agricultural aid money), it will Connecticut's decision to get out of be one of the nation's most formidable riskier and more expensive job of curing mosquito control "wasn't a question of mosquito control operations. Still, the disease once it starts. reallocating the money to some other message is clear: The days of funding The critics of the Minnesota program program,"says Paul Schur,director of the without scrutiny are over. don't really dispute that.What they ques- state's Environmental Health Division. Are the critics overdoing it?That is not tion is how much of the MMCD's $10 "It was a question of whether we needed an easy question. For one thing, mos- million annual budget is really going into it. We had a budget crunch and we had quito control is not just a matter of nui- disease prevention. "They hide behind no disease that we could trace to the mos- sance control—perhaps even more,it is a the fear factor," says Mondale. "Nobody quito in Connecticut." In the absence of public health issue. Surveillance and iso- wants to take away the disease piece,but disease,various regions of the state began lation programs combat the spread of dis- they spend $700,000 on disease control quarreling among themselves over where ease and provide the first defense against and $9.3 million on nuisance abatement. the money should be spent. "We were epidemic."Ted Mondale has targeted the That's money that could go to clean up mostly dealing with salt marsh coastal wrong program," says Robert Graham, polluted industrial property or to provid- mosquitoes," says Schur. "Inland legisla- executive director of the American Mos- ing affordable housing." tors didn't want to pay for what was quito Control Association. "Mosquito essentially a coastal program." control is a successful enterprise in pro- here would seem to be a simple Since the elimination of Connecticut's tecting the public's health. The problem answer to the criticisms of excess in program, in part because it didn't serve is, when you do something well, people Minnesota and other places: sepa- statewide interests, several townships take you for granted." rate out disease control from nuisance have contracted with private firms to con- The MMCD cites citizen satisfaction abatement, and stick to disease. It is not duct mosquito control. But smaller-scale ratings in the 70 percent range and says it as simple as that,warns George Craig,an programs have their own set of problems. destroys more than 90 percent of the entomologist at Notre Dame University. "If Guilford and Milford share a marsh female larvae that hatch in its territory "Disease outbreaks occur in unpre- and Guilford is spraying and Milford every year. It points to virtual elimination dictable times and places," he says. Any isn't, the mosquitoes don't stop at the of the potentially disastrous La Crosse virus present in an animal population can town line,"says Schur. In addition,many encephalitis.Should the program be cut,it be spread by mosquitoes. Therefore, he towns can't afford to use "source reduc- warns, residents can look to a resurgence insists, disease surveillance and nuisance tion" techniques, which are less Kaz- in cases of mosquito-borne disease. "How control"work hand in hand." ardous biologically,because they're more do you evaluate risk until you've had a Craig cites equine encephalitis as an expensive and require larger scale efforts. major outbreak?" asks Graham. "We are example. A virus which localizes in So towns mostly spray larvicides—no+ the first vanguard against emerging infec- horses, it is fatal in 80 percent of cases if the best method from an environmenta: tious diseases.We let down our guard and passed to humans, with half of the sur- point of view. we don't know what will happen." vivors suffering permanent brain damage. There's no question that cutting any That may sound like a self-interested "There's no vaccine,"Craig says. "All you mosquito control program involves a cer- argument, but it is not difficult to find can do to protect yourself is stay inside tain amount of risk assessment bingo. respected scientists who agree with it. and use repellent." In his view, keeping Nervous-system damage from La Crosse Roger D. Moon, an entomologist at the down the population of"nuisance" mos- encephalitis can take two or three years to University of Minnesota, says that pre- quitoes amounts to an investment in show up in the children it strikes. Ohio, ventive mosquito control provides the avoiding catastrophes that nobody thinks which has cut back on mosquito control best insurance not only against epidemics about until they happen. but historically has had a problem with?_ of encephalitis but against malaria. "In For its part, Minnesota's Metropolitan Crosse,won't really know for a few ye—;s the United States,we don't have malaria Mosquito Control District is unwilling what the consequences of abandoning its currently," he says, "but people come even to entertain any distinction between effort might be. "We'll see retardation into the country with the parasite in their its disease-prevention and nuisance- from fever of unknown origin and we blood all the time. Without adequate abatement tasks. "We take a comprehen- won't know why," Professor Craig wo e mosquito control and disease surveil- sive view of health, not only as the ries."When you have an outbreak,people lance, we could easily get malaria back." absence of specific diseases but as a qual- say, `Why didn't you do something about In Moon's view, mosquito control pro- ity of life issue, and we need a large net- it yesterday?' Well, yesterday th D vides enough prevention to avoid the work to deal with these issues effectively," weren't willing to pay for it." 48 GOVERNING July1995 YY � � �� -- � lw� .i'erl t't�rifrol 'It�cl�rricilzris Vol . 11, No. 13 18 June 1995 Snap, Grackle, Pop, Night Grispies! "Bug zappers . " Sure, they' re impressive, but do they work? First , let ' s make it clear that we' re not talking about the insect light traps ( ILTs ) that are used by the pest control industry in indoor facilities such as restaurants, hospi - tals , etc. These professional light traps can be very effective in elimin- ating flies , when placed and serviced correctly. By "buy zappers, " we mean the ultraviolet, inexpensive homeowner models that people mount in their backyards to control mosquitoes and other biting flies . People that own them, swear by them. They point to the piles of dead insects that they empty out of the trap each morning. what they don ' t realize is that the great majority of the insects that they zapped are harmless . Bug zappers actually attract and kill very few mosquitoes . Instead, they draw hordes of insects into the yard that wouldn ' t have been there otherwise . Yard zappers have never fared very well in research tests . In one study, after 11 days of continuous operation , the zappers failed to reduce the mosquito biting rate in the yards . Only 3% of the thousands of insects collected in the traps were female mosqui - toes . The majority ( 89% ) of insects that were zapped were midges . Midges look a lot like mosquitoes and most homeowners wouldn ' t be able to tell them apart . But midges don ' t bite and f . they' re considered beneficial . J _ Instead of buying bug zappers to control " mosquitoes, people would be better ad- vised to eliminate or treat the standing water in which mosquitoes breed , change, t reduce, or shield outdoor lights , remove heavy shrubbery to reduce mosquito rest- ing places , and use repellents . 4' Irftti Pittln&Assorinfrc, l!tr, All ri1Zl1fc „•cp07•Yrf. flnnnfhoti>rd rrvr l'r­,tif ,,: ' MOSQUITO MONITORING AND CONTROL IN THE PANTHER CREEK MARSH 1993 BY TERRY WHITWORTH, PhD Entomologist The 1993 mosquito season was a difficult one with frequent rainfall, cool temperatures and reduced evaporation rates which resulted in large mosquito populations all summer long. Compared to 1992, dominant species were significantly different. Aedes species populations were very high through May and June, while Culex species and Coquillettidia populations -were much lower. Culiseta species populations averaged slightly higher than last year. Aedes species are aggressive biters and; create almost all the serious complaints. They are poorly attracted to light traps so their total populations tend to be underestimated relative to other mosquito populations. Tests with dry ice, which emits carbon dioxide gas, attracted Aedes no better than light traps. The most effective way to sample Aedes that I have found is for people to stand in the sample area and collect all mosquitoes that are attracted to them. This technique is time consuming and probably not needed for our purposes . Mosquito breeding was heavy this year and being limited to the use of only Scourge for fogging was frustrating. Scourge is so short- lived (4 hours or less) , that populations recovered within 1 to 3 days when breeding conditions were optimum. We have been using Permethrin for other customers and, even with heavy mosquito population, we get significant population reductions for 4 to 7 days. I would encourage approval of the option to use Permethrin, at least when problems are severe. I think the timing and coordination of this years program was very good. Despite all the homeowner complaints, I think it could have been much worse. For 1994, I would recommend timing similar to this year. Table 1. Female mosquitoes collected in 1993, by date. Data from the Otness and Busch site are combined. Date Aedes Coquillettidia Culex Culiseta Comments April 20 3 3 3 29 4 May 04 8 Altosid treat done 11 25 4 18 37 4 3 24 22 3 5 June 02 18 4 9 08 13 5 5 5 15 19 13 5 4 22 8 3 24 5 30 5 12 7 one light trap mal- functioned July 06 4 1 8 4 13 5 4 7 7 20 3 4 4 3 One light trap mal- functioned 27 2 10 2 30 2nd Altosid treat done • MOSQUITO MONITORING AND CONTROL PANTHER CREEK MARSH 1991 BY TERRY WHITWORTH, PhD Entomologist Monitoring for mosquitoes was begun April 15 , 1991 and continued until September 25 , 1991 . Light traps were located at two strategic sites above the swamp . One was behind the home of Lyle Otness , 2521 Talbot Crest Road, and the other was by the Merle Busch property on Busch Place South. Although these sites were fairly close together they attracted mosquitoes from different portions of the swamp. The Busch area consistently yielded about 30 to 50% more mosquitoes than the Otness site . Male mosquitoes (which are non-biting ) were collected beginning April 15 and the first female appeared on April 29 . From April 29 to June 19 only Aedes were collected . After June 24th Aedes tapered off and occurred at lower levels for the rest of the summer. Coquillettidia began appearing in early July and were gone by mid-August. Culex began appearing in mid-July and were the dominant mosquito from mid-August on . Culiseta were occasionally collected from mid-June on, but never occurred in large - numbers . Efforts to collect larvae in the swamp were largely unsuccessful , since many of the breeding sites can ' t be reached on foot . Light traps rarely collected Aedes , even when they were seen in large numbers . Most specimens were collected swarming around us as we worked with the light trap . Because of this we carried nets and spent at least 10 minutes at each site collecting adults in the area. The lack of a similar monitoring program in past years may R explain why few Aedes were ever collected in the past. Almost all citizen complaints coincided with peak populations of Aedes . This is consistent with my experience in other areas . Aedes are aggressive and painful day biters, while Coquillettidia and Culex are usually not seen until dusk. Culex tends to be shy and cautious but can become a nuisance inside homes at night. It is also a known disease carrier in the northwest. Culiseta occurs during the day but is not present in sufficient numbers to be a problem. The May 14 treatment of the swamp with 5 month Altosid briquets probably significantly reduced mosquito populations , although there is no way to determine level of control . The three Scourge treatments produced immediate population reductions which appeared to last 1 to 2 weeks. The 1991 mosquito season was exacerbated by an unseasonably wet spring and early summer resulting in high water levels in the swamp much later than usual . Our inability to anticipate water and weather conditions makes planning control programs very difficult. For the 1992 season I would recommend we continue the monitoring program using the same start date as in 1991 . It ' s important to check regularly in the spring to identify the time when adult females appear in the upland areas . However monitoring may be r suspended by the end of August based on the data we gathered this year. I would also recommend dropping the use of the 5 month Altosid briquet and going back to the 30 day briquet at less than half the cost. A portion of the savings can be used to fund additional Scourge treatments when Aedes occur in large numbers . rr Table 1. Numbers of female mosquitoes collected in 1991 by date. Data includes light trap collections from the Busch and Otness property and hand collected adults observed around collection sites. Date Aedes Coquillettidia Culex Culiseta April 15 0 0 0 0 23 0 0 0 0 29 1 0 0 0 May 06 5 0 0 0 14* 0 0 0 0 21 15 0 0 0 28 18 0 0 0 June 04** 13 0 0 0 10 20 0 0 0 17 60 0 0 1 24** 4 0 0 0 July 02 7 36 2 0 08 4 55 0 0 15 4 19 0 0 19** 4 2 1 0 22 0 24 11 0 31 4 70 40 4 Aug. 05 0 8 3 3 12 13 5 52 0 19 1 0 11 3 26 2 1 22 3 Sept. 03 5 0 16 1 09 4 0 21 0 16 4 0 8 0 25 1 0 6 2 * Altosid Treatment ** Scourge Treatment • Figure 1 Numbers of female mosquitoes collected in 1991, by date, at the Panther Creek Site. 70- 60 50 0 0 40 U 0 E °1 3 0 ro E v �+ C u x x w 20 0 0 z 10 x x 0 _ Culiseta 0 0 April May June July Aug. Sept . x-Culex o-Culiseta 70- 60 Ul 50 Coquillettidia v 0 u .4 0' 40 Aedes 0 E < v i 30 v w 0 20 0 10 x x o x x x i ►- I April May June July Aug. Sept . ;:-Aedes o-Coquillettidia MOSQUITO MONITORING AND CONTROL IN THE PANTHER CREEK MARSH,-1992. BY TERRY WHITWORTH, PhD Entomologist Monitoring for mosquitoes was begun May 12, 1992 (first sample taken May 19, 1992 ) and continued until August 17, 1992 . Light traps were located at two strategic sites above the swamp, one was behind the home of Lyle Otness, 2521 Talbot Crest Road, and the other was by the Merle Busch property on Busch Place South. These are the same sites as last year. Although these locations were fairly close together, they attracted mosquitoes from different portions of the swamp. The Busch area consistently yielded about 30 to 50% more mosquitoes than the Otness site. As in 1991, Aedes were the dominant mosquito from mid-May to mid- June. This year Aedes disappeared from samples in early July, while in 1991 they persisted throughout the sample period. It is likely that the regular fogging, this year helped bring this about. It also resulted in few if any homeowner complaints after about mid-June. Coquilletidia populations paralleled last year, with two peaks about 3 weeks apart, but total numbers were less than last year. Overall Culex was the most common mosquito collected in 1992 . It appeared much earlier than in 1991, but generally in lower numbers. This mosquito rarely causes biting complaints because it is a night flier and its bite is not painful. However, because it can transmit disease, it is a concern. It breeds in the stagnant pools that form as the wetlands water level drops, and has multiple generations. Culiseta were also more common than in 1991, although they never occurred in large numbers. Culiseta breeds in permanent pools and may have multiple generations. Their numbers were too low to be a major concern. For 1993, I think we should consider a program similar to the one in 1992 . To prevent an early outbreak, I would recommend the program commence on May 1st and the fogging should include the North end of the wetlands from the beginning. Table 1. Female mosquitoes collected in 1992, by date. Data from the Otness and Busch site are combined. Date Aedes Coquillettidia Culex Culiseta May 19 12 0 3 3 27 15 0 1 5 29* - - - - June 01 9 1 3 3 09 11 0 13 2 15 7 2 8 5 23 5 43 15 2 29 2 25 17 3 July 10 0 4 15 6 17 0 3 14 4 23 0 15 17 4 31 0 7 32 4 Aug 07 0 1 19 0 17 0 0 12 1 * Altosid Treatment i I B U I L D - I T i o O a � 14%" F k @ c 3/C E o ! --I V/s FRONT VIEW Bat House big brown bat can eat 3,000 to 7,000 insects every night—try that with BUILDING THE BAT HOUSE your electric bug zapper! Cities in the Midwest are now building and 1.Cut the partition and back. installing bat houses to reduce their bug-spraying costs,and you can follow suit by building a few for your own backyard with inexpensive, un- 2•Cut the front. 3.Cut two filler blocks.Bevel if desired. treated lumber for just a few dollars. Studies have shown that bat houses 4. Nail the fillers to the lower, inside work best when located within about 1,000 feet of water (where lots of bugs edges of the front and back. hang out).The houses should be oriented toward the east or southeast so 5.Score or otherwise roughen the inside they warm tip quickly in the morning. surfaces of the front,back and partition. Nail your finished bat house to an unobstructed spot 12 to 15 feet above 6. Cut the two sides with a 15' slope on the ground. An outbuilding or tree trunk is ideal—but don't mount it too the top end. near living quarters, since smelly bat guano (which is high in nitrogen and 7. Nail the sides to the front,back and great for your garden once composted) may accumulate under the bat partition. house and attract roaches and mites. (If the bat house isn't occupied by the 8•Cut a roof.Bevel edges 15°. second season,change the location.) Our design is bottomless to discourage 9•Nail the roof to the house. 10.Drill mounting holes as appropriate rodents and other animals from nesting in it, and has roughened-up inte- and finish as desired. rior surfaces for the bats to cling on. i —Mike.Ferrara 68 ORGANIC GARDENING B U I L D - I T RECYCLE LEAVES & WASTE THIS FALL WITH A BAKE,kl The New Baker"' Yard Waste Management ! \ ROO _ g Heavy-duty 6121912 1'/z[> f cap. i 3/4typ i o- 53/4' - — 14'/8" )z 2a I[P tn)d PTo RECYCLE NATURES WASTE NATURALLY WITH A YARD WASTE MANAGEMENT 16" SYSTEM'",THE POWERFUL,SENSIBLY PRICED RECYCLING SOLUTION FROM BAKLIC ! PUT FALL LEAVES,PRUNINGS,THATCH AND GARDEN LEFTOVERS TO WORK FOR 12314 16' YOU. THE BAKER'S RECYCLES WASTE INTO MOISTURE-SAVING MULCH,SOIL-ENRICIIING COMPOST AND DECORATIVE CIIII'S FOR LANDSCAPING. I MANY MODELS TO CHOOSE FROM. GAS AND ELECTRLIFE-TIME ENGINES. AND THE IrOMADO Products, BAKER"LIFE-TIME WARRANTY. 71nc.3 SEE YOUR LOCAL DEALER FOR A - - ----- e N114 W18605 Clinton Drive $ DEMONSTRATION. OR CALL OR WRITE Germantown,WI 53022 To us FOR MORE INFORMATION, (414)251-4600/FAX(414)251-6510 I R I CUT YOUR �r� ROUGH OR FILLERS j SCORED --- HEATI NG COSTS Model SURFACE BK50 by as much as 60% with our SIDE VIEW all cast iron (WITH SIDE REMOVED) AirtightBarrel Stove Kits / Our Stove Kit converts a 55 or 30 gallon dnlrn MATERIALS into a highly efficient wood burning heater pro- 1 Y4 X 11 X X 16"(partition) ducing over 150,000 BTU/hour. Our Double Model 1 /.X 11XX 16" (back) Barrel Kit bums secondary gases as they recirculate 1 %X 11%X 12.'/<"(front) BK150 r I through the top chamber producing over 2401000 t/. \ vot \1 2 X Y4 X 11'b"(fillers) �_" pir 2 '/.X 5%X 14;"(sides) BTU/hour.Uses 6'pipe,nuts and bolts included. "oV,so i 1 '/.X 5h X 14X"(roof) -Easy to Build 3.•—.,a 6 3d finish(nails-fillers) -Full cash refund if not delighted 30 6d finish(nails) -All shipments made within 48 hours upon receipt of order. All cast iron "Cam-lock" r' MODEL DELIVERED construction door latch III !! 1 (barrels not OTY DESCRIPTION PRICE III included) "Ainite" - BK150E Stove Kit $58.88 gaskeled Offer for forty eight y't feed door 'cool handle contiguous states. BK50E Adaptor Kit $34.88 Counter Touch" Canada and Alaska Total Weigmed d Separate ash door customers please call. draft ial FOR RUSH ORDERS CALL TOLL FREE 1-800-222-6950 ❑VISA ❑M/C# Exp. Date ❑Check enclosed ❑COD(Add$6.00 Handling) Name Phone f Street y City State Zip \ o � ELZAN CORP. DEPT.OG12,400 WEST 17TH STREET,HOLLAND,MI 49423 N<)k'RAIBLIR i!)4)I 69 42 Living in Harmony Living in Harmony 43 shape, insulation, and placement), the size and shape of internal roosting spaces, roughness of by wrens, mice, squirrels, or other unwanted the surfaces to which the bats must cling, and ,, {+ e_ animals. the distances to drinking and feeding areas. - * The Missouri-style bat house is large enough Mark Hodgkins recently studied bat nursery to shelter hundreds of bats. It is approximately roosts in manmade structures in the north- 71/2 feet long,4 feet wide, and 21/2 feet tall and is western United States and found that they were t open at the bottom for entry. The main bat all located within roughly a thousand feet of a yl roosting areas consist of variably spaced (3/4 river, lake, or pond. He also found significant inch, 1 inch, 11/4 inch),wooden partitions inside preferences for particular roost sizes, shapes,. ' two 6 x 1 x 1 foot compartments joined side by and temperature profiles. Many roosts, espe- `, side.Spaces at the ends permit bats to enter the cially small ones, cooled so much at night that "attic"above the compartments,but most seem they fell below the optimum temperature range to prefer the crevices.The greatest advantage of the attic is probably its influence in stabilizing for their nursery colonies. It was probably for I daily temperature fluctuations in the roost. As this reason that orientation to the sun was found to be important. Roosts facing east and the name implies,the first one was built in Mis- southeast were optimally oriented to the morn- souri,and the success of that one led to the con- ing sun, heatingmore struction of several more in Minnesota. Of the quickly and having a higher daily heat gain. a Missouri-style bar house at first two placed in Minnesota parks, one was On the basis of these findings, Hodgkins de- the Lindbergh Interpretive Cen- occupied within a year, and the second after a signed two kinds of artificial bat houses,one for ter in Little Falls,Minnesota. year and a half. Their little brown bat occu- This house was first occupied a pants apparently preferred the 3/a inch crevices. small insectivorous bats, such as mouse-eared bats, and the other for their larger counter little more than a year after it The most carefully monitored house was ini- was built,and it now contains a tially occupied by 15 bats. This number in- parts, the big brown and pallid bats. His bat colony of little brown bats that houses were similar to an earlier design,known has doubled in size each creased to 40 the second year and to more than as the "Missouri style" bat house, except that for the Year 85 the third. Its population is still growing, and i p past three years. Eleven 10 additional Missouri-style bat houses recently they were smaller, for convenience of construc- similar houses are now used in tion, and better accommodated the bats' ob- other Minnesota parks. one have been built for other Minnesota parks. served preferences for roosting crevice depths house is capable of sheltering In response to public interest in bat houses, and widths. A much smaller bat house of Euro hundreds of bats. (Photograph Bat Conservation International (BCI), a non- pean design has been successful in some areas by Earl Johnson.) profit organization dedicated to bat conserva- and occasionally has attracted as many as 30 tion,bat research,and public education,has de- bats. However, these houses are too small to signed a version that is a compromise between the large complex types and the smallest simple provide temperature stability, and they do not ones. The BCI design is relatively easy to build, offer a variety of crevice widths to accommo- date different species. It seems likely that they but still incorporates several of the crevice are used primarily when better alternatives are widths and depths suggested by Hodgkins, to unavailable. Sometimes these have solid bot- accommodate large and small species. Its 27- toms,making them more likely to be taken over inch height and small attic help to provide more stable temperatures over a greater range. IL t ai(>iJ Manufacturer's Name Roussel Blo Corporation Emergency Telephone No 201-871-0771 Address INurnher,street,City,State and Zip Code): . P.O. Box 1077, 400 Sylvan Ave., Englewood Cliffs. NI 07632 full Name Scourge"Insecticide with SBP-1382 Piperonyl Butoxide 4% + 12% MF EPA Registration Number 432-716 Chemical Family: Insecticide Formula Mixture -t � I r� ►�a 11 1!/1i At:i��. ►i1`; IrJc.►r1;R►aI .r11 '= HAZARDOUS MIXTURES OF OTHER LIQUIDS, SOLIDS, OR GASES % 11 V (Units) Resmethrin (Insecticide)CAS #10453-86-8 18 NA Piperonyl Butoxide(Insecticide)CAS #51-03-6 54 NA Aromatic Petroleum Solvent (mixture of Hydrocarbons) 25 100 ppm DOT Information: Insecticide.Liquid N.O.S. 111 1'111''=1t Al, 1►AUA Boiling Point: Approx. 185°C Vapor Pressure(mm Hg.1: NA Vapor Density(Air=I): NA Solubility in Water: Insoluable Specific Gravity(H,0=1 ): 1.01 g/ml Appearance and Odor: Clear brown liquid, characteristic odor. ,':1;1 'ii'Wi`l I111 IIt1,: Aiv10 IWAIIA Flash Point (Method Used): 145OF(T.C.C.) Extinguishing Media: Foam, CO,, Dry Chemical Special Fire Fighting Procedures: None Required Unusual Fire and Explosion Hazards: None I r i SCOURGE 18't+ 4 '1,1% MF A EPA Reg. No. 432-067 3 f Cl1<>ra 11111;AIArt I1A1.AVI IIA n Threshold Limit Value: See Section II Effects of Overexposure: May cause irritation on prolonged or repeated contact. Harmful if swallowed Emergency and First Aid Procedures: If in eyes or on skin: Flush with plenty of water. Get medical attention if irritation develops. If swallowed: Call a physician or Poison Control Center. Do not induce vomiting. This product contains aromatic petroleum solvent. Aspiration may be a hazard. < 140 l VI Ii'I AC.i 1111 1'V I ►A-I A Stability: Stable Conditions to Avoid: Extreme heat or sources of ignition. Incompatability(Materials to avoid): None Hazardous Decomposition Products: None Hazardous Polymerization: Will not occur Conditions to Avoid: None >t if'1,1101<I VII *1't1.1• t?1" 1,1-;AV 1'1'(H t t>t Steps to be Taken in Case Material is Released or Spilled: Wear skin and eye protection during cleanup.Contain spill and keep out of sewers and drains. Soak up liquid with absorbent and shovel into waste container. Waste Disposal Method: Wastes resulting from the use of this product may be disposed of on site or at an approved waste disposal facility. 14 (: i l(IN Vill "O'1l.( '1/11' 11"I1I I ( I If'If"! If 11 t t1'1`\1,n l 'I ai t Respiratory Protection (Specify type): NIOSH Approved if needed to supplement environment controls. Ventilation: Local Exhaust: Control to TLV Mechanical (General): Control to TLV Special: None Other: None Protective Gloves: Rubber Gloves Eve Protection: Goggles or safety glasses * (' i t(,l+I IX '�1`fi•('.Ii11 I'?'1;('A111 t(�r1'; Precautions to be Taken in t landling and Storing: Avoid breathing vapor or spray mist. Avoid contact with skin, eyes or clothing. Other Precautions: Wash thoroughly after handling material with soap and water. The foreeoinc data has been compiled from sources which the company.in eord faith.believes to he dependable and IS m curate and rellahle to ifre beet of our knowledi'v and 1-11 I f lowever the comp»nv cannot make any warranty or representation restxvc tine the accuracy or complelcm—of the data and asstmtee rn+re":pontiihility for anv liability+n dam.u• . tefaline,theretoorforadvisinf!vonrer!ardini!theprotectionofyouremployees.customersorothers(hers should make theirownteststodelerminenc�apt+licaf+ilitvolsuchinl+am:,rira, "r the suitabiliry,1 anv prceluctc for tip•cific ttsc r + CODE 72682 s PERMANO FO 31-66 EPA REG. NO. 4816-740 EPA EST. NO. 279-NY-1 DIRECTIONS FOR USE A Synergized Permanone Formulation for quick It is a violation of Federal law to use this product in a manner knockdown and effective control of Adult Mosquitoes, inconsistent with its labeling. Gnats, Biting and Non-biting Midges, Blackflies and other Biting Flies This product is a synergized concentrate of permethrin containing For Application only t.7y Mosquito Abatement Districts, 2.86 lb/gallon permethrn and 6.09 lb/gallon piperonyl butoxide. It Public Health Officials,and other trained Personnel in may be applied undiluted or may be diluted with mineral oils(such as Mosquito Control Programs Orchex or Klee rol), cottonseed oil or other suitable non-phytotoxic ` ULV-suitable oil. This product is specifically designed to be applied ACTIVE INGREDIENTS 2 tPermethrin: 31 28,/° as a ULV spray. 'Piperonyl Butoxide,Technical ......... f.......... ....... ................................66.00% INSECTS CONTROLLED INERT INGREDIENTS..................................... ................................................2.72°° 100.00% A.do� mosquitoes, gnats, hieing and non-biting midges, black flies, stable flies, horse files,deer flies and other biting flies. 'Equivalent to 52.8%(butylarbityl)(6-propylpiperonyl)ether and 13.2% related compounds. WHERE TO UfiE t(3-phenoxyphenyl) methyl (-/-) cis trans 3-(2,2 dichforoethenyl)2,2 dimethyl cycbpropanecarboxylate Cis Trans ratio: Max 65%(±) trans and min.35%. Areas that may be treated for insect control include,but are not limited (±) cis, to;parks,campsites,woodlands,athletic fields,golf courses,residen- tial areas and municipalities, gardens, playgrounds, recreational PERMANONE is a Registered Trademark of Fairfield American areas and ove grown waste areas. Do not use on crops used for Corporation food,forage or pasture. KEEP OU T(�F REACH OF CHILDREN USE PRECAUTIONS ` In treatment of corrals, feed lots, swine lots and zoos, cover any CAUTION exposed drinking water, drinking fountains and animal feed before STATEMENT CF PRACTICAL TREATMENT '"� application. Do not contaminate pasture land, cropland, poultry IF SWALLG'v' ED - Cali ,hysidan or Poison Control Center. Drink ranges or water supplies from spray drift. o;ie or two glasses of water and induce vomiting by ioucni;ig back of ,Not to used within 100 feet 30 meters) lakes and streams. throat with finger. Do not induce vomiting or give anything by mouth ) to an unconscious person. Allow 24 hours before retreating. Do not apply more than once in a IF ON SKIN: Wash with pienty of soap and water and get medical g PP Y attention. 24 hour period. IF INHALED: Remove victim to fresh air. If not breathing, give artificial respiration. Get medical attention. USE DIRECTIt;M IF IN EYES: Flush eyes wi h plenty of water. Get medical attention if Best results are expected b a hcation when weather conditions irritation persists. favor an inversion of temperatures in the area treated, and when the See back panel for additional precautionary statements wind is not excessive. Apply using vehicle mounted non thermal ULV equipment to create an insecticidal swath. Apply when there is a light breeze(i.e. 5 mph) NET CONTENTS and apply in drection of breeze to obtain maximum swath and better 0 740 030191D distribution. M CONTINUED ON REVERSE N O� co rV Fairfield American Corporation 201 Route 17 North, Rutherford, NJ 07070 Early morning and evening are the best times for application. Temperature S FORAGE AND DISPOSAL fluctuations may require periodical adjustment of equipment to deliver the desired flow rate at the specified speed of travel This flow rate must be main- Do not contaminate food,fused or water by storage or disposal. tained to insure the distribution of the proper amount of active ingredient per STORAGE:Do not store at temperatures below 407(4.5°C). If this material has acre. been exposed to temperatures below 407 (4.5`C) there may be precipitation. Application can be made with LECO ULV Cold Aerosol Generator, Microgen, Check for crystallization. If evident, warm to 807 (26.5°C) and thoroughly mix pp before using. DO NOT USE,: OPEN FLAME. Curtis, London Aire or other equipment designed for ULV aerosol generation. PESTICIDE DISPOSAL: VVastes resulting from the use of this product may be DIRECTIONS FOR GROUND APPLICATION disposed of on site or at an approved waste disposal facility. CONTAINER DISPOSAL: Triple rinse (or equivalent). Then offer for recycling or reconditioning, or puncture and dispose of in a sanitary landfill or by other Use non-thermal ULV portable backpack sprayer or vehicle-mounted non-ther- procedures approved by state and local authorities. mal ULV equipment to cover a 300 ft. swath width. Adjust to deliver droplets of 15-30 microns mass median diameter. Apply at rate of 0.0035 or 0.007 lb PRECAUTIONARY STATEMENTS permethrin/acre. HAZARDS TO HUMANS AND DOMESTIC ANIMALS This can he achieved under different conditions by alterine the dilution rate,flow CAUTION of insecticide from the vehicle, and vehicle speed as shown in the following. Harmful if swallowed,absoted through skin or inhaled. Prolonged orfrequently DILUTION TABLE repeated skin contact may cause allergic reactions in some individuals. Avoid contact with skin, eyes or clothing. Avoid breathing vapors. Wash thoroughly SPACE SPRAY (300' swatLwi= with soap and water after handling. Remove contaminated clothing and wash before reuse. Application Equipment F+ow Rate (fl oz/min) Rate Speed (np-W Undiluted 'Diluted 1:2 'Diluted 1:4 ENVIRONMENTAL HAZARDS 0.0035 5 0.5 1.5 2.5 This pesticide is extremely toxic to fish and aquatic invertebrates. Do not apply lb aVacre 10 1.0 3.0 5.0 directly to water or wetlands (swamps, bogs, marshes, and potholes). Do not permethrin 15 1.5 4.5 7.5 apply when weather conditions favor drift from treated areas. Drift and runoff 20 2.0 6.0 10.0 from treated areas maybe hazardous to aquatic organisms in neighboring areas. Do not contaminate water when disposing of equipment washwaters. Do not apply when wind speeds exceed 10 mph. �.uv"i 3 5 i his pesociae is higniy toxic io bees exposed to ci:ect treatment or to rusicaues Io ai/acre 10 2 6 10 remaining on the treated areas. Do not apply this product or allow drift when permethrin 15 3 9 15 bees are actively visiting the treatment area. Applications should be timed to 20 4 12 -- provide the maximum pos:.;ible interval between treatment and the next period of bee activity. 'Dilution instructions specify volume ratios of product:diluent (ie. 1:2 equals 1 volume part PermanoneFs mixed with 2 volume parts diluent). Buyer assumes all risks of use, storage or handling of this material not in strict accordance with directions,given herewith. 'DIRECTIONS FOR AERIAL APPLICATIONS This product may be used in fixed-wing and rotary aircraft capable of making a ULV application of undiluted spray formulation. Applications should be made when little or no wind (less than 5 mph) is present at the same target application rates as for ground based ULV. 'Aerial application not authorized in the State of Florida CITY OF RENTON PANTHER CREEK WETLANDS MOSQUITO ABATEMENT PROGRAM MOSQUITO CONTROL ALTERNATIVES REPORT Prepared for The City of Renton Planning/Building/Public Works Department Prepared by Terry Whitworth, PhD. Entomologist Whitworth Pest Control, Inc. TABLE OF CONTENTS Page Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Problem Statement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 Review of Mosquito Control Tactics in other Areas. . . . . . . . . . . . 7 Comparison of Mosquito Control Options. . . . . . . . . . . . . . . . . . . . . . 11 Biological Control Alternatives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Chemical Control Alternatives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Biorational Chemicals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Synthetic Chemicals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Citizen Mosquito Control Options. . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 DOE Mosquito Control Policy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Conclusions and Recommendations. . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23 Appendix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24 2 A Phil-OiCLY INDEX TO APPENDICES N07- A77 j�q APPENDIX#1 HYDROLOGICAL FACTORS APPENDIX#2 BEST MANAGEMENT PRACTICES FOR MOSQUITO CONTROL AND FRESHWATER WETLANDS MANAGEMENT APPENDIX#3 MOSQUITO MONITORING AND CONTROL PANTHER CREEK MARSH 1991 REPORT APPENDIX#4 DEPARTMENT OF ECOLOGY DRAFT POLICY FOR APPLICATION OF MOSQUITO CONTROL INSECTICIDES. APPENDIX#5 CITY OF RENTON MOSQUITO ABATEMENT PROGRAM 1991 WILDLIFE SURVEY(Includes a summary of the 1989 and 1990 wildlife surveys for comparison) INTRODUCTION This report is to satisfy a condition of a determination of non-significance issued by the hearing examiner on February 27, 1989 . The City was required to explore mosquito control options for the Panther Creek Wetlands with a review of positive and negative impacts of various mosquito control alternatives . The City has made a variety of mosquito abatement efforts in and around the Panther Creek Wetlands since the mid-1970 's . The author has been involved in these efforts since 1979 . Control efforts were begun in response to complaints from homeowners in the Talbot Hill area above the wetlands. Early measures which involved misting wetland borders with pesticides, did little to abate the problem. In the early 1980 's the dominant species of mosquitoes were identified and several aerial applications of residual synthetic pesticides were made. These treatments appeared to be effective, but environmental concerns eliminated this approach by the mid-1980 's. Since then, the city has directed its efforts toward solving the mosquito problem, while also addressing citizen and governmental concerns about protecting the fragile wetland environment. Historically mosquito-borne diseases have caused more human illness and death than all other diseases combined. As a result, 3 mosquitoes have probably been studied more than any other insect. Mosquito control principles have been long-established and remained virtually unchanged for the past 40 years. The most effective, and long lasting form of mosquito control is the elimination of mosquito breeding habitat, by filling, dredging, channelizing or water level manipulation. Other options include biological, and chemical control. The value of preserving large rural wetlands as sites for waterfowl breeding and feeding has been recognized for decades, but small urban wetlands like the Panther Creek site, until recently, were considered to be of little value. However, as urban wetlands have been eliminated, with expanded construction of parking lots, driveways, and buildings, flooding problems have increased. This has lead to an increased awareness of the value of urban wetlands and growing political and regulatory requirements to protect them. THE PROBLEM In 1991 the author conducted a detailed study of the mosquito problem in the Panther Creek Wetlands ( see attached 1991 mosquito monitoring report) . There are three common genera of mosquitoes which occur in the Panther Creek Marsh, Coquillettidia, Culex, and Aedes . 4 Coquillettidia includes only a single species, (C. preturbans) while Culex and Aedes include several species each. Also found occasionally in the area were Culiseta sp. and Anopheles sp. Coquillettidia preturbans have been the most serious pest in the marsh. It thrives in this environment because its larvae attach to rooted aquatic vegetation such as cattails, one of the dominant plants in the marsh. This species has only a single generation per year unlike most mosquitoes . Eggs may hatch as early as March and adults usually begin emerging in early May. Adult emergence can occur over a 2-3 month period, though most adults will have emerged by mid-July. Incidentally, this species occurred in much lower numbers and much later (July) in 1991 than in past years. Culex species have free-floating larvae which thrive in stagnant pools throughout the swamp. They emerge later than Coquillettidia and are not nearly as pesky to humans, though they can carry disease. Members of this genus have multiple generations, but at the Panther Creek site, they tend to appear, from mid-summer until late September. Species of this genus favor warm, stagnant or polluted water. Aedes species are known as floodwater mosquitoes and also have free-floating larvae. They are serious pests where 5 fluctuating water levels occur. Species of this genus were responsible for the majority of complaints received in 1991 . The best defense against this pest is to have a water management plan which prevents frequent water level fluctuations. This species has multiple generations and under the right conditions (warm weather after rain or high water) produce new generations in as little as one week. This genus was rarely collected in past years, but it occurred in large numbers in 1991 from April to September. Aedes does not come to light traps as well as the other two groups and many were hand-collected during our monitoring effort. Perhaps they were abundant in previous years, but not collected because we relied almost exclusively on light traps for our samples in the past. The mosquito problem in the Panther Creek wetlands has resulted in a classical dilemma which is also occurring throughout the nation wherever wetlands and human populations are in close proximity. Governmental regulations, backed by citizen support, require wetland preservation, but those same citizens have little tolerance for mosquitoes . Wetland protection efforts have limited many proven mosquito abatement tactics, such as filling, dredging, or draining wetlands . Until recently, conventional synthetic 6 pesticides such as Dursban 2G provided economical, effective mosquito control. In the past few years "environmentalist" opposition to these pesticides has grown and resulted in regulatory changes which greatly limit aquatic insecticides that can be used at the Panther Creek site. The result is the only pesticides allowed at this site are the "biochemical" materials which include Altosid and Bacillus thuringiensis israelensis (Bti) . These products can be effective when used properly, but they are much more expensive. A cost comparison example which includes only material cost is mosquito treatment with Dursban 2G costs about $5 . 00/acre while Altosid XR costs $550.00/acre. The Panther Creek site has up to 65 acres of wetlands ( see June 1991 wetlands inventory) so the total chemical cost for Dursban 2G would be $300 . 00, while the cost of Altosid XR would be $33, 000 . 00 , a hundred fold difference. Bti is much less expensive, but is very short-lived (about 24 hours) and must be reapplied regularly to be effective. It also will not control Coquillettidia, which lives underwater attached to the roots and stems of plants (most larvae float at the surface) . A REVIEW OF MOSQUITO CONTROL TACTICS IN OTHER AREAS In an effort to develop an overview of mosquito control options, I interviewed a number of mosquito control experts statewide and 7 nationwide. Names were obtained from the membership rolls of the American Mosquito Control Association. Most experts on mosquito control manage mosquito abatement districts in areas where mosquitoes pose a human disease threat. These managers are invariably publicly funded, with limited budgets, and usually use proven control techniques. Until recently, proven techniques meant, where possible and economically feasible, to fill, dredge, or drain mosquito breeding sites. In areas where this was not feasible, long lasting synthetic larvacides and adulticides were used. They were relatively inexpensive, and effective. However, environmental concerns grew about the effect of these pesticides on non-target organisms, and the public has demanded safer alternatives. Unfortunately, "safer" has often meant more expensive and less effective. Districts on the East Coast and California are ahead of those in the Northwest, because they were pressured to change their tactics many years ago. This pressure has developed only recently in the Northwest. The following is a summary of mosquito control programs I investigated throughout the United States . Within Washington Jim Thompson, head of the Grant County Mosquito Abatement district and Executive Director of the Northwest Mosquito Control Association is probably one of the most innovative mosquito 8 managers in the state. Other active managers I interviewed were Dick Morton (Benton County) , and Al Huber (Yakima County) . Each of these individuals are responsible for mosquito problems in eastern Washington, where disease transmission is a major concern. They have recently begun moving away from hard chemicals and are increasing the use of products like Altosid and Bacillus thuringiensis. However synthetic larvacides and fogging of adults is still a major part of their programs. Limited funds have kept them from researching much new technology. In Portland, Oregon, Peter DeChant is in charge of the Multnomah County Mosquito Abatement Program. As in Washington, the program has minimal funds and creative research opportunities are very limited. In California Dr. Bruce Eldridge is director of mosquito research at University of California, at Davis. He is an acknowledged mosquito expert and is pursuing a variety of creative mosquito control approaches. I discussed the Panther Creek Wetland problem with him in detail, but he could add little to what we already know. He provided me with names of several other experts including Dr. William Hazelltine, Manager of Butte County, California, Mosquito Abatement District, Cy Lesser Maryland Department of Agriculture, and Judy Hansen, Cape May, New Jersey. I called each 9 of these persons and found that, though they have different mosquito problems, they are also dealing with the same small pool of solutions. Their districts also suffer from underfunding which makes it difficult to research new mosquito control options . In California and on the East Coast the use of Gambusia (top-feeder minnows) to control mosquito larvae is one of the most effective alternatives to pesticides. The use of biological control agents will be discussed in more detail later. In the process of preparing this document, I reviewed many articles and texts. One of the best is titled, "Guidelines for the Ecological Control of Mosquitoes in Non-Tidal Wetlands of the San Francisco Bay Area" . Research for this document was supported by the California Mosquito and Vector Control Association and the University of California Mosquito Research Program. Ecological control is defined as "the exploitation of ecological relationships to reduce population size or production rate of a disease vector or pest organism" . This method leads to reduced average and peak mosquito densities and is useful where environmental concerns require a reduction in the use of pesticides. It is also useful to consider ecological factors when restructuring wetlands to ensure you don't create new mosquito habitat. In general, this control method alone, is not acceptable 10 to citizens who want to preserve wetlands while having no mosquitoes. It appears that, if ecological controls are to be used in the Panther Creek Wetlands site, some major changes must be made. To determine what changes would be most likely to provide the desired results, many hydrological factors must be taken into account ( see Hydrological Factors, Appendix #1) . Wetlands typically experience extreme changes in quantity and quality of water supplies. A major rainstorm may introduce sediments, oils, and other pollutants to the wetland. An extended drought may cause it to go dry. Pollutants like oil wastes are toxic to surface-breathing species of mosquito larvae, as is drought, since water is essential for larval development. Pollutants like fertilizers and sewage lead to increased plant and microbial development and may actually increase mosquito populations. Detailed studies by the city are underway to determine the hydrology and hydraulics of the Panther Creek Wetland site. There studies are important to understand the effects on mosquito populations. COMPARISON OF MOSQUITO CONTROL OPTIONS The following is a review of the Cities choices with the Panther Creek Wetlands, as I see it: 11 Option 1 . Suspend city mosquito control efforts and let homeowners handle the problem individually. Pros - Saves the city money. - Does not disturb the wetland/wildlife water quality. Cons - May anger residents above wetlands. - May lead to homeowner remedies which are hazardous to the environment. Since state law ( see RCW 17 .28 . 170 ) mandates that property owners must control mosquitoes on their property, the City may be obligated to control mosquitoes originating on their property. Option 2 . Continue treating water with Altosid Briquets and fogging upland areas with Scourge, make no habitat changes. Pros - Does not require large up-front dollars . - Wetland is preserved. Cons - Mosquito control success will vary depending on water levels, etc. - Pesticide usage will remain the same or higher depending on water levels. - Would cause continuing concerns about impact of treatments on environmental quality. This approach is probably the best choice until effective, acceptable alternatives have been clearly identified. Option 3 . Make habitat changes to improve mosquito control efforts such as access paths through vegetation or small ponds. Improve paths along edge. Pros - Relatively inexpensive. - Would allow more consistently effective mosquito control. - Would not change the present wetland. 12 Cons - Channels would have to be kept open. - The program relies primarily on the use of pesticides. This approach is similar to option 1 and should be considered, if the final decision is no major habitat modification will be done. Option 4 . Provide wetland outflows with gates to allow manipulation of water levels in the wetland. Pros - Would be relatively inexpensive. - Would not require extensive changes in the wetlands. - Would provide a method of environmental control of mosquitoes. Cons - Altering water levels will have a negative impact on some marsh inhabiting plants and animals. - Without channels, it is not clear how well the wetlands would drain if gates were opened. Option 5 . Channelize the wetlands to prevent standing water. Pros - Would reduce mosquito breeding sites. - Would reduce size of areas that need to be treated, and reduce pesticide use. Cons - Could reduce size of wetlands. - Would require periodic maintenance to prevent channels from filling. - Could cause downstream flooding. - Would be relatively expensive. This proposal and the ones that follow may invoke the "no net loss of wetlands" policy of the City, State and Federal government. These changes would certainly change the nature of the wetlands, but whether it would cause a net loss would have to be determined by regulatory officials. Option 6 . Build a series of ponds connected by channels with water levels controlled by flood control gates . 13 Pros - Wetlands nature is retained. - Open water would encourage fish, ducks, geese. and other wildlife, while reducing mosquitoes. - Mosquito predators such as Gambusia may survive and breed in this situation. - Would reduce size of mosquito breeding sites and amount of pesticides needed. - Water levels could be manipulated to control mosquitoes. - Could make the area attractive to the public for fishing; bird watching; etc. Cons - Ponds would have to be dredged periodically to keep silt out. - Application of aquatic herbicides may be needed to control floating weeds and rooted vegetation. - Could be expensive to develop and maintain. Option 7 . Construct a large lake with a flood gate. Pros - Would reduce mosquito breeding sites. - Could open the area up for public recreation. - Would allow water level manipulation which would help control mosquitoes. Cons - Would be expensive to construct. - Would eliminate wetlands, as such. - Would require aquatic weed control. - Could contribute to downstream flooding. Option 8 . Utilize a combination of these options . Construction of a series of ponds or a lake, creates open water which reduces survival of larval mosquitoes because of wind and wave action. To minimize mosquito and weed production these water bodies need steep sides, and around 1 foot drop for every 3 feet from shore. The water needs to be as deep as possible, at least 6 14 feet deep at low water levels to minimize rooted aquatic vegetation and maximize fish survival. This option comes with its own share of problems. Ponds or lakes will tend to fill with silt from runoff if they are not dredged periodically. If they are allowed to fill, another swamp will be created. Open water can also develop problems with Eurasian milfoil and algae. These problems can be treated with aquatic herbicides, but there many associated expenses and environmental concerns. Equipping the outlet with a gate will allow manipulation of water levels and provide a means of controlling mosquito larvae by desiccation. Fluctuating water levels have been used successfully in California and on the East Coast to control many species of mosquitoes. Once eggs have hatched, many larvae will die when water levels drop suddenly. This approach risks aggravating Aedes problems if previously dry areas are re-wet for a week or more. Another solution would be to construct a series of ditches which would keep the wetlands free of standing water. When water accumulates after rains, it would be drain out rapidly and provide little mosquito breeding habitat. However, this would also change the nature of the wetlands . For some ideas on how to modify mosquito breeding habitat see New Jersey's recommendations, Appendix 2 , on "Best Management Practices for Mosquito Control" . 15 BIOLOGICAL CONTROL ALTERNATIVES The Panther Creek Wetlands contain a variety of vertebrates which can reduce mosquito populations (see 1991 Wildlife Survey) . The wetland is populated with three-spined sticklebacks, and several species of frogs which will feed on mosquitoes. It also has several species of swallows which feed almost exclusively on flying insects. Though bats were not inventoried in the wetlands, it is likely that some inhabit the area and they feed nocturnally on flying insects like mosquitoes. Studies have shown that three-spined sticklebacks feed extensively on mosquito larvae and pupae. However they rarely occur in sufficient numbers to cause a major reduction in mosquito populations (Chapman, 1985 ) . Since these fish are already present in the Panther Creek Wetlands, its apparent that they alone cannot keep breeding mosquitoes under control . There are a variety of insectivorous birds inhabiting the wetlands. Birds such as tree swallows could be encouraged by the installation of nest boxes along the wetland borders. It is generally believed that, while animals like birds and bats can reduce mosquito populations, they cannot control them. The use of stocked Gambusia sp (mosquito fish) to reduce mosquito populations has been well-documented (Chapman, 1985 ) . Under ideal 16 circumstances, this minnow can substantially reduce populations of mosquito larvae and pupae. It is a hardy and adaptable fish which can be quite prolific. It cannot be considered a panacea for mosquito problems and there are many records of control failures with Gambusia. It is best used as part of an integrated pest management (IPM) program. This fish has been implicated in the elimination of rare and endangered minnows (through habitat destruction) and will eat eggs of desirable fish species . Any decision to stock Gambusia would require prior permission from the Washington State Department's of Wildlife, and Fisheries. CHEMICAL CONTROL ALTERNATIVES Chemical applications to water for mosquito control are regulated by the Department of Ecology (see attached DOE mosquito control policy, September 1991) . Normally only Bacillus thuringensis israelensis (Bti) and methoprene liquid (Altosid) are allowed for use on mosquitoes by Department of Ecology in the state of Washington. To justify the use of "stronger" chemicals it must be shown that Bti or Altosid would be ineffective or fail to abate a public health problem. BIORATIONAL CHEMICALS Bacillus thuringensis israelensis (Bti) (Teknar and Bactimos) is an endospore forming bacterium which when ingested by early instar 17 larvae can kill them. It has the advantage of being relatively host specific, but it must be reapplied frequently to be effective, and as a result is very expensive. It also does not control some mosquitoes, such as Coguillettidia which attach to vegetation below the water surface. Methoprene (Altosid) is a growth regulator which prevents the emergence of normal adult mosquitoes. It is available in liquid, pellet, and briquet form. The advantage of this product is that it does not remove immature mosquitoes from the food chain and it tends to have minimal impact on non-target organisms. It is also available in a long lasting briquet form which reduces the frequency of treatments needed. All biological chemicals tend to be much more expensive than synthetic chemicals. SYNTHETIC CHEMICALS Larvacides The DOE mosquito control policy (as of September 1991 ) lists acceptable synthetic mosquito control larvacides. The list is in order of perceived hazard to the aquatic environment. Monomolecular surface film (Aerosurf MSF) leads the list along with Golden Bear Oil. Products such as temephos, fenthion, and chlorpyrifos are at the end of the list because they tend to be broad spectrum and eliminate many non-target invertebrates from the aquatic environment. 18 Adulticides Mosquito adulticides are applied to upland areas only and therefore are regulated by the Washington Department of Agriculture. There are no special restrictions on adulticides and therefore any product registered in Washington State and labeled for outdoor misting of mosquitoes can be used. In environmentally sensitive areas, products like Scourge (SBP 1382 ) , a synthetic pyrethroid, are preferred. This product is short-lived (about 4 hours) and is safe around birds and mammals. In heavy mosquito infestations it must be reapplied frequently to achieve control. A newly registered product for adult mosquito control, in brush away from water, is permethrin (also a synthetic pyrethroid) which can last up to 7 days after application. The manufacturer is presently seeking registration of this product in Washington State. Products like Dursban (chlorpyrifos) are also long lasting and effective but there is more concern about its effect on non- target organisms . CITIZEN MOSQUITO CONTROL OPTIONS There are a variety of things homeowners can do to reduce mosquito breeding on their property. Standing water anywhere outdoors will provide mosquito breeding sites. Things like bird baths and wading pools should be emptied weekly to keep larvae from reaching the 19 adult stage. Other possible breeding sites include old tires, plugged gutters, and mud puddles. These tactics will reduce Culex populations, but would not effect Aedes or Coquillettidia which breed in wetlands. Homeowners can also go indoors to avoid mosquitoes and equip doors and windows with screens. When outdoors they can wear protective clothing and mosquito repellent. Many people resent the fact that they can't enjoy their property at certain times of year, without protecting themselves. They tend to blame the city for the mosquitoes, since the city owns some of the property where the mosquito populations are originating. DEPARTMENT OF ECOLOGY MOSQUITO CONTROL POLICY In September 1991, DOE issued a final draft of a mosquito control policy (DOE Mosquito Control Policy, Appendix) . This policy was developed by a committee of state regulators (DOE, Department of Health, and Department of Agriculture) and industry representatives, including the author. To apply pesticides to water for mosquito control a short-term modification permit must be obtained from DOE. To obtain this permit the applicator must: 1 . Present a treatment plan, 2 . Comply with the State Environment Policy Act (SEPA) checklist requirements and 3 . Get a determination of nonsignificance (DNS) . The DOE must be informed 20 of the time period when treatments will occur and have access to the results of any monitoring program available. The public must be notified at least 24 hours in advance of any major treatment. DOE regulates only pesticide applications to water while the Department of Agriculture regulates upland treatments. No state permit requirements exist for applications to upland areas. CONCLUSIONS AND RECOMMENDATIONS The solution to this mosquito problem must be left to the citizens and the political entities governing the Panther Creek Wetlands. In my opinion, the approach which would provide the most reduction in mosquito populations, while retaining the wetland character, is the construction of a series of ponds with water control gates . This would result in improved fish and waterfowl habitat and the open water would greatly reduce mosquito breeding. However, this approach would be expensive to develop and might be costly to maintain. Individuals or special interest groups who insist on preserving wetlands need to recognize that preservation comes with a price tag. A wetland so close to an urban area will be a continuing source of citizen complaints about mosquitoes and require ongoing city expenditures to keep them in check. If the site were to become a public recreation area, perhaps better funding to maintain 21 the area would follow. In Washington State the Centennial Clean Water Act, managed by the Department of Ecology, provides grants to local communities to preserve and manage wetlands. The city may want to consider pursuing assistance through this avenue to improve the wetlands. Before initiating expensive changes in the Panther Creek site, the City should recognize that mosquitoes are breeding throughout the Highway 167 corridor and adults can fly up to 7 miles from where they breed. The brushy hillside between Talbot Hill and the wetlands will continue to harbor some adult mosquitoes from elsewhere, even if they are controlled in the wetlands. 22 REFERENCES Chapman, H.C. Editor. 1985. Biological Control of Mosquitoes. American Mosquito Control Association, Fresno, CA. 218 P. Collins, J.N. & V.H. Resh. 1989. Guidelines for the Ecological Control of Mosquitoes in Non-tidal Wetlands of the San Francisco Bay area. California Mosquito and Vector Control Association. 93 P. Mulhern, T.D. 1980. A Training Manual for California Mosquito Control Agencies. CMCA Press, Visalia, CA. O'Carroll, G. 1988. Best Management Practices for Mosquito Control & Freshwater Wetlands Management. New Jersey Department of Environmental Pretection. 74 P. 23 r Feature Mythical Mosquito Control Lee Mitchell Economics and science play impor- mosquitoes bitin ale in the v rds. a zapper 14 hrs a day, in good weather tant roles in every mosquito control Biologists are concerned about the and bad, from the time of the first mos- program. By virtue of common sense high number of non-pest insects such quito hatch in the spring until the end and public overview we utilize person- as beetles and moths that are attracted of November. nel, equipment and insecticides in an and killed by bug zappers. Some of Even though we attempt to mosquito efficient manner to guide our pro- these insects are beneficial as natural adulticiding with insecticides as grams.We wisely encourage citizen in- biological controls on other insect specific as possible in terms of flow put and participation in our communi- pests and others are important in the rates,droplet size and time of applica- ty activities. How then do we respond food chain. Some people will operate Continued on page 19 to requests and comments regarding mosquito control methods that have lit- ` Nature was a powerful opponent in tle scientific support? ba P PP f 'Naturalists often claim that bats,pur those days, and not least among her s A pie martins and other insect-eating dangers were the hordes of insects that Wi birds can adequately control mosquito � '' � £� plagued area residents. populations. Homeowners purchaser` 7 fi. Campbell's bat tower was intended to combat mosquito swarms for the early electrocuting insect traps and elec '. LFk +' developers of Temple Terrace,who were tronic insect re ellers b the P Y e attempting to transform the groves of thousands. Industries advertise the in- Temple(of course)oranges into a posh sect repelling qualities of all-purpose ? ' surburban community.The Tower was lotions such as Skin-So-Soft° and the designed to house more than 1,000 bats, hybrid Citrosa plant. Your response to imported from Texas, who were each such inquiries may cost you either supposed to devour some 3,000 mos- pub)ic support or precious operating quitoes per night. funds as you sink money into a losing Despite a cavelike interior, nurseries proposition. for baby bats,and ribbed hanging racks, the bats never took to Campbell's tower. ELECTROCUTORS Instead they flew south, or wherever y ' . � `'" bats go, after being terrorized by local ' teen-agers--leaving the developers of The ultraviolet or black lightele Temple Terrace with a $10.000 failure trocut9l-_1La s, also known as I n (in 1924 dollars, mind you). Zappers° , Bug Blasters© and Big iF Abandoned,the tower stood in a state Wackersl�l are probably the most L � ', t1:- ;;t of disrepair until historic interest was popular choice by homeowners for 7 1 revived in 1976, and plans were made mosquito control.One industry official Bat tower on Sugarloaf Ky in South Florida.Photo by the city to purchase the tower's land estimates that up to 1.75 million bug by Doug wassiner and refurbish the strange landmark. zappers are sold annually in this coun- Fifteen thousand dollars was granted try at upwards of$100 each These traps Nature, Man gang up to bring that year by the federal Department of down bat tower Housing and Urban Development to do attract and kill thousands of insects, restore the tower, but confusion over but often, as Gord Surgeoner and who owned the land delayed the pro- Blair Helson showed in Canada 15 by J. P. Faber, Staff Writer jest until a 1979 arsonist's fire that gut- years ago and Roger Nasci confirmed Precariously balanced on the muddy ted the structure put an end to the idea. in Indiana nearly a decade ago, mos- edge of the Hillsborough River just east quitoes cotupris_e less than 5 percent of Tampa lie the ruins of a bizarre ex- (This article appeared in the July 11, 1981 of the catch. Of even greater impor- periment. Here, 57 years ago, Dr. issue of the Tampa "Times. Reprinted tance was the finding that these Charles Campbell's 36-foot bat tower here by permission of the Tampa devices did not reduce the number oT failed to beat back the forces of nature. Tribune.) 18 WING BEATS, SUMMER 1992 Continued from page 18 ty to release the fresh aromatic are also some attractants in the com- citronella oil. The Citrosa plant does mercially available product and that tion, many people still prefer the non- not bloom or reproduce naturally but the primary repellent component in discriminatory electrocutor traps and may be started with leaf cuttings. Skin-so-soft is better than DEET. The then blame the decline of favored Although there are numerous anec- mechanisms of how repellents work backyard songbirds on the use of dotes about the effectiveness of Citrosa are not know. pesticides. Dr.George Craig,Jr.,of the t ere are no scientific studies that sun- Most of us are well aware that the University of Notre Dame goes so far port the idea that the Citrosa plant are public expects and in some cases even as to call bug zappers a "fraud on the effective repellents. The plant leaves demands that insecticides should be public" must be touched or disturbed to very specific in their action. It is release the citronella aroma. As a humorous to note that Skin-So-Soft can REPELLING DEVICES house plant the lemony fragrance is also be used for 31 purposes, including quite pleasing, although the plant will removing chewing gum from hair, The word fraud can also be used to spread and grow to a height of several skin, and most-non-porous surfaces; describe a variety of mosquito repell- feet if it is not pruned. Plants sell for cleaning ink from skin and most-non- ing devices. At least ten studies in the about $12 and is tender below 45F. porous surfaces; cleaning ink from past 15 years have unanimously de- The proprietary bath oil Skin-So-Soft skin and most vinyl and painted sur- nounced these devices as having no will repel mosquitoes in the lab but, faces; cleaning paint brushes; remov- value whatsoever. Eadly_ BrsianG of like citronella,it may or may not be ef- ing tar from car finishes without mosquito repelling devices use elec- fective on individual humans. The damaging paint and as a suntan oil. tromagnetic energy while more recent same applies to Culicoides biting designs produce high frequency midges. In laboratory trial, Rutledge PURPLE MARTINS D nd• Some of these devices are and coworkers estimated that Aedes capable of being "fine tuned" by the oegypti was about 30 times more sen- An appraisal of the benefits of utiliz- purchaser,with instructions indicating sitive to the most commonly used in- ing purple martins and bats for mos- that the device can be adjusted until sect repellent DEET IN, N-diethyl-m- quito control offers fewer oppor- the correct frequency is found to repel toluamide)than to Skin-So-Soft. Jerry tunities for humor and may lead to mosquito pests. None of these devices Butler, however, has found that there Continued on page 20 have proven effective in repelling mos- quitoes when evaluated scientifically. COMPLETE SPRAY T ere are many instances in which devices have been marketed that have little or no testing to support their ef- i The CC145 is the perfect.sprayspraying ' '' pesticides ficacy claims. It may also be noted that I tem for aquatic ' managementand and'other corrosives. Order ' ur contrlCall us toll free: in some of the product advertising, ' 'uitd y.the built-in tote' It's ' and CCI-15ht �' tray makes it easy to 1-800-346-7867:. homeowners are urged to use these devices to rid their home of pests handle. Thousands of these units are in without the need to inhale "even one sprayuse,...it's field proven! And you won't er CHEMICAL breath of poisonous spray." Such featuresand quality-for this low price. C01CONTAINERS91NC. statements play on public fears that in- , , •, P.O. ' ' secticides are harmful to humans and should be avoided. Weighs Less Than 28 lbs. Can Be Shipped Via UPS CITROSA MOSQUITO FIGHTER° AND SKIN-SO-SOFT° Tote Tray With Handles The Citrosa "Mosquito Fighter" Poly Tank r = 4 plant and Avon's Skin-So-Soft bath oil are also marketed for their mosquito . repelling qualities. Citrasa_was genetically created by crossing tissue � _ ". s � cultures o an rtcan geranium wt ' the Grass o hina.The grass contains ', k citronella oil,which has been used for ' Gw many years as the active ingredient in 18,Blass Wand&Nont mosquito repellent coils and candles. Also available in 35, 50 and 100 gallon models The geranium gives the plant the abili- TOTALLY PORTABLE! ORDER TODAY! WING BEATS, SUMMER 1992 19 Continued from page 19 houses for insectivorous birds to be safe and effective. Although specifically for the purpose of mos- ultraviolet electroculor traps will at- quite heated debates. It has been quito control, we should build them tract and kill mosquitoes,they are often known for many years that purple mar- simply to attract these interesting birds misused and kill large numbers of in- tins consume large numbers of flying for their esthetic and educational, nocuous insects. Vertebrate predators 'nsects. Proponents of the value of pur- value. it is a mistake to promote the such as purple martins and bats will ple martins have often used the state- welfare of those wildlife species that ment by Wade that "a purple martin only seem,beneficial to man in some will eat 2,000 mosquitoes in a clay." He obvious way also stated that. 10,000 to 14,000 mos- ,l uitoes could be consumed per day BATS when mosquitoes are plentiful. All of Wade's values were non-scientific More recently some naturalists have estimates based on his belief that mar- become interested in the welfare of tins had an extremely rapid digestive bats and have noted the value of insec- process and metabolism. He reasoned tivorous species in controlling mos- that an adult purple martin would have quito populations. They have subse- to consume its body weight each day quently recommended the construc- in flying insects in order to survive. tion of bat houses for the protection Thus, if an average adult martin and propagation of those species that weighted 4 oz., this would be the have been evicted from caves or human equivalent of 14,000 mosquitoes.Ac- residences."Chat such an idea is a new tually. Wade's math was faulty because one may be quickly refuted by referr- he greatly overestimated the weights of ing to the literature. During the 1920's an individual mosquito and martin several large bat towers were con- and many more would have to be con- strutted near San Antonio, Texas and 6 sumed to provide the necessary Key West and Tampa, Florida with the Purple Martin with preferred prey. nutrition. intent of controlling malarial mos- Wade did not analyze the stomach quitoes with high numbers of insect- consume mosquitoes and should he contents of martins but did recognize eating bats. Mosquito populations considered as part of an integrated that their diet included flies, were not reduced but the large ac- pest management program. A public dragonflies,beetles, moths, locusts and cumulations of guano was sold at a education program should accompany other bugs in addition to mosquitoes. profit. the use of artificial cavity-type houses Unfortunately, mam naturalists have The bats of temperate regions re- for the promotion of insectivorous bats failed to differentiate hetween Wade's main almost exclusively insectivorous. and purple martins. Predators can not theories and scientific: fact. As with martins, bat food consists totally replace source reduction and Exhaustive studies of the diet o1pur- mainly of beetles, wasps, ants, flies, chemical control. Electronic mosquito pie martins several ornithologist in- stoneflies. mayflies, moths and repellers have a dismal performance dicate that while mosquitoes are a part grasshoppers. Mosquitoes rnak record and should be vigorously of the diet they eat many more wasps, less than 1 percent of their diet discouraged. The Citrosa Mosquito �—---—— ants, house flied crane flies, stinkbugs, aiih—oug the percentage may e ig per Fighter plant has no proven merit and tree hoppers,beetles, butterflies, moths when mosquitoes are abundant. The research is needed to demonstrate any and dfagonflres.—Mosgiut e-s make up evidence from stomach analysis and mosquito repelling qualities that it may less than three percent oTtheir diet. feces examination show that inset- possess. Personal protection from mos After all it takes a lot of mosquitoes to tivorous bats do help regulate some in- quitoes is best gained by the proper use add up to one dragonfly. sect populations, both beneficial and of DEFT and other topical-repellents. Ornithologist James Hill is founder pest species — but not mosquitoes. including Skin-So-Soft. and director of the Purple Martin Con- However, bats are worthy of our pro servation Association. He is especial- tection regardless of their capacity or ly anxious to dispel the longstanding proclivity to consume pest or vector Lee Mitchell is a Biologist notion that a single martin eats populations of mosquitoes. with the Ibledo Area Sani- thousands of mosquitoes in one day t9 y District, 5015 Stickney According to Hill. "The number of SUMMARY Avenue, Toledo,Ohio 43612; mosquitoes that martins eat is extreme 419/726-7891; FAX: 419/ ly insignificant, and they certainly it is our responsibility to educate the � ' 726-7721. don't control them" Rather than erect puhlic about mosquito control and to martin houses and other cavity-type utilize those methods that are known 20 WING BEATS, SUMMER 1992 Fairfield American Corporation is committed to the development of a comprehensive range of Public Health insecticide products. Our parent company,The Wellcome Foundation Ltd., is a recognized leader in the discovery and development of pharmaceutical and public health products. Our aim is the pro- tection of man and his environment through the creation and integrated use of quality public health products. This brochure has been written to answer PERMANON E° your questions about Permanone 31-66. We 31-66 welcome any additional questions you may have about this product and invite you to A write us at the address on this brochure. FOR PUBLIC HEALTH PROGRAMS ANSWERS TO COMMONLY ASKED QUESTIONS Permanone is a registered trademark of Fairfield American corporation. Fairfield American Corporation Orchexc is a registered trademark of Exxon Corporation. 201 Route 17 North Rutherford, NJ 07070 (201) 507 4880 What is Permanone 31-66? How is Permanone 31-66 used? synergized permethrin to be at least 2 times t more effective than the commonly used OP adulticides against Aedes taeniorhynchus, Q, Q. Aedes albopictus,Anopheles quadrimaculatus, Permanone 31-66 is a synergized pyrethroid Permanone 31-66 is an oil-based concentrate. Culex species,and other troublesome species. insecticide. It has been specially formulated It can be diluted with commonly used oils for use as a mosquito adulticide for Public for use through ground based ULV machines What are the chances of increasing Health Programs. and other conventional spray equipment. g Permanone 31-66 is labeled for use as a ground mosquito resistant problems based space spray or can be applied undiluted A through the use of Permanone What are the active ingredients in as an aerial ULV. Suitable solvents include 31-66? Permanone 31-66? but are not limited to Orchex 796, HAN, light There is no reason to anticipate high mineral oils and kerosene. permethrin resistance levels among U.S. - --_- - mosquitoes.To date, U.S. mosquitoes tested Permanone 31-66 contains permethrin, a ! Is Permanone 31-66 safe to use? have not shown any field resistance, even pyrethroid insecticide, and piperonyl butox- when there has been a history of high levels Q;z ide, a synergist. Worldwide, permethrin is an of resistance to other insecticides. Recent " " `"adulticide of choice due to its quick insecti- Both permethrin and i eron I butoxide studies have shown that the risk of cross cidal activity and its effectiveness against a p p p Y resistance between pyrethroids and other in- have an excellent record of safety. Permethrin, secticides may have been over-emphasized broad range of insects including many OP Y P resistant strains. The use of permethrin in though synthetic,retains many s.the favorable since different resistance mechanisms appear public health programs is documented by properties of natural pyrethrins.This to be involved.Also, piperonyl butoxide is insecticide has high activity while maintaining known to delay or reduce pyrethroid resistance the World Health Organization and Pan Y PY American Health Organization. Piperonyl low acute and chronic toxicity to mammals in insect strains where the resistance is due butoxide has been known as an effective and birds. y in sunlight and also has a very butoxide breaks down to increased mfo activity. synergist for many years, originally for very quickly n s pyrethrins. low toxicity to mammals and birds.Permanone 31-66 is a non-irritant and virtually odorless What is the fate of Permanone in use.These properties coupled with the low 31-66 in the environment? What is a synergist? application rates required give this insecticide a high safety margin in use. Q, Permethrin is rapidly degraded in soil, and What are the effective use rates piperonyl butoxide breaks down in sunlight A synergist is an active ingredient that b Qwhen applied as a space spray? within 30 minutes. Permethrin binds strongly to soil,so the deposits are not readily leached. g Y itself has no toxic properties, but enhances Degradation of permethrin in the soil occurs the toxicity of an insecticide. PipergnyJ` Use as a ground based or aerial space spray by a combination of microbial and chemical butoxide inhibits mixed function.�Qxidases r at levels up to 0.007lbs of permethrin per actions. In water courses the compound is (mfos), enzyrhes'that metabolize foreign acre. Flow rates and vehicle speeds may be rapidly absorbed onto organic matter and compounds, in this case permethrin. varied to deliver the recommended dosage sediments to be degraded, resulting in very rate and swath width of 300 feet. Optimal low aqueous concentrations.The field half-life droplet size is approximately 20 microns. of permethrin, like all pesticides, will vary What is unique about Permanone greatly depending on rainfall,temperature, 31-66? Is Permanone 31-66 effective sunlight and amount of organic matter present. against OP resistant strains? Permethrin is not a persistent insecticide. This is the only highly concentrated synergized pyrethroid specifically formulated for dilution Synergized permethrin has often shown with oil. Permanone 31-66 forms stable clear superior killing properties when used to dilutions and is convenient for a range of control OP resistant strains.Recent laboratory adulticide application parameters. wind tunnel tests and field trials have shown Code 72682 Permanone® 31 ,66 Public Health Adufticide "A Y -Highly concentrated -Quick knockdown -Quick knockdown -Oil dilutable -Contains synergized permethrin k Permanone"' 31-66 is a highly Permanone 31-66 has been designed concentrated synthetic pyrethroid for use as a ground based or aerial adulticide. I, has been specifically space spray for application through formulated for use in Public Health conventional spray equipment. Flow programs. Permanone 31-66 rates and vehicle speeds may be contains permethrin, a pyrethroid varied to deliver up to 0.007 lbs. of insecticide, and piperonyl butoxide, a permethrin per acre. A swath width synergist. This combination of active of 300 ft. and optimal droplet size of ingredients provides quick insecticidal approximately 20 microns is c action. It is effective against a broad recommended. spectrum of insects, including OP resistant strain. Permanone 31-66 is a non-irritant and virtually odorless in use. These Permanone 31-06 effectively controls p,operties, combined with the low mosquitoes and other biting insects in application rates required, give this a variety of tr,;atment areas. insecticide a high safety margin in use. Permanone 31-66 is convenient to use for a broad range of adulticide Technical data on Permanone 31-66 appiication parameters. i he product provided on the back of this sheet. may be used undiluted. It may also be mixed with commonly used oils to form clear s,,able dilutions. Suitable solvents include, but are not limited to, Orchex 706, HAN, light mineral oils, and kerosene. ® Permanone is a registered Trademark of Fairfield American Corporation Fairfield American Corporation 201 Route 17 North Rutherford, NJ 07070 (201)507-4880 Code 72682 t' t µ Technical data Ingredients F- Active Ingredients %w/w Z" k;. *Permethrin 31.28 F` **Piperonyl Butoxide, Technical 66.00 ,;` 4 Inert Ingredients 2.72 100.0% n ` (3-phenoxyphenyl) methyl (t)cis/trans 3-(2,2 dichloroethenyl) 2,2 di met hylcycloprnoanecarboxylate t cisltrans ratio: Max 65% (t) trans and min. 35% (t) cis. " Equivalent to 52.8% (butylcarbityl) (6-prrspylpiperonyl) ether and 13.2% related compounds w Physical data . Specific Gravity (20/20°C) 1.107 Color Dark Amber Brown ' Weight/Gallon 9.23 _ Flash Point (TCC), OF >200 Active Ingredient Content 2.86 lbs. permethrin/gal. 6.09 lbs. Pbo, Tech./gal. Available sizes Container Size Net Weight 4 x 1 gal. 36.8 lbs. G: plastic container 30 gal. drum 275.7 lbs. ' t` 1,� Material Safety Data Sheet Permanone@ 31w ..................................................................................................................................................................................................................................... SECTION I-IDENTIFICATION OF PRODUCT g ........................................................................ ---............................................................................... ................................................... �R MANUFACTURER'S NAME: FAIRFIELD AMERICAN CORPORATION gat 201 ROUTE 17 NORTH RUTHERFORD,NJ 07070 PRODUCT CODE:72682 NAME:PERMANONE 31-66 CHEMICAL NAME:See Section II C.A.S.NAME:See Section II C.A.S.NUMBER:See Section II CHEM.FORMULA:N/A MOLECULAR WGT.:N/A CHEM.FAMILY:Mixture E.P.A. REG.NO.:4816-740 E.P.A. EST. NO: 279-NY-1 HAZARDOUS MAT'L.DESC.: N/E HAZARD CLASS:None ....................................... ..... ................................. SECTION II-HAZARDOUS COMPONENTS OF MIXTURES ............................................................................................................................................................... MATERIAL PERCENT Permethrin i(3-ptrerioxyphe.iyl)mcthyl(+/-)cis/trans 3-(2,2 dich1oroethcnyl)2,2 .N' dimethyl cyclopropanecarboxylatel CAS#52645-53-1 31.28 Piperonyl Butoxide,Technical[(butylcarbityl)(6-propylpiperonyl)ether and related compounds) CAS#51-03-6 66.00 ..................................................................................................................................................................................................................................... SECTION III-PHYSICAL DATA ......................................................................................................................................................................................................... ...................... ODOR:Mild sassafras&type odor MELTING PT.:N/A LBS/GAL:9.23 PARTICLE SIZE: N/A COLOR(G-H): 16-Da0:amber CLOUD PT.: N/A BOILING PT.:N/A PERCENT VOLATILE:N/A VAPOR PRESSURE:N/A EVAPORATION RATE:N/A VAPOR DENSITY: N/A �FLASHPOINT:>200°F REFRACTIVE INDEX:N/E SPECIFIC GRAVITY. 1.107 BULK DENSITY(FLUFFED):N/A BULK DENSITY(SETTLED):N/A SOLUBILITY(OIL):miscible SOLUBILITY(WATER):insoluble APPEARANCE:thick,bark amber liquid ..................................................................................................................................................................................................................................... SECTION IV-FIRE&EXPLOSION HAZARD DATA ..................................................................................................................................................................................................................................... ' FLASH POINT(METHOD USED):>200°F(TCC) AlFLAMMABLE LIMIT(LOWER):N/E FLAMMABLE LIMIT(UPPER):N/E `- FIRE EXTINGUISHING AID`Foam,Water Fog,Dry Chemical,CO2 foam £r. SPECIAL PROCEDURES: Use self-contained breathing apparatus,cool fire-exposed areas and equipment. „. UNUSUAL FIRE /EXPLOSION HAZARDS: None 4 : ..................................................................................................................................................................................................................................... d SECTION V-HEALTH F�DATA . .... .......................................................... TOXICITY CATEGORY:III ORAL LD50:>500 mg/kg DERMAL LD50: >2.02 g/kg INHALATION LD50:>4.39 mg/L EYE.EFFECTS:Slightly Irritating SKIN EFFECTS:Irritating �? THRESHOLD LIMIT VALUE:N/E �) ADDITIONAL COMMENTS:None CHEMICALS LISTED AS CARCINOGENS OR POTENTIAL CARCINOGENS: NATL.TOXICOLOGY PROGRAM:None IARC MONOGRAPHS:None OSHA:None SECTION VI- SPECIAL PROTECTION =t EYE PROTECTION:Safety goggles or glasses SKIN PROTECTION:Rubber or impervious gloves RESPIRATORY PROTECTION:None necessary for normal use OM ER PRECAUTIONS:General(mechanical)exhaust PERMANONE 31-66 Fairfield American Corporation 201 Route 17 North Rutherford, NJ 07070 (2(1)507-4860 FAIRFIELD AMERICAN CORPORATION MATERIAL SAFETY DATA SHEET- 72682 .................................................................................................................................................................................................................................................... SECTION VII-EMERGENCY&FTRST AID PROCEDURES ................................................................................................................................................................................................................................................... IF SWALLOWED: Call physician or Poison Control Center. Drink one or two glasses of water and induce vomiting by touching back of throat with finger. Do not Induce vomiting or give anything by mouth to an unconscious person. IF IN EYES: Flush eyes with plenty of water. Get medical attention If irritation persists. IF ON SKIN:Wash with plenty of soap and water and get medical attention. IF INHALED: Remove affected person to fresh air. If not breathing,give artificial respiration. Get medical attention. .................................................................................................................................................................................................................................................... SECTION VIII-EFFECTS OF OVER EXPOSURE ..........................................................................................I.......................................................................................................................................................... NOT ESTABLISHED .................................................................................................................................................................................................................................................... SECTION LY- SPILLAGE OR LEAKAGE PROCEDURES .........................................................................................I.............................................................. ...................................... PESTICIDE STORAGE AND SPILL PROCEDURES: Do not store at temperatures below 40°F. If this material has been exposed to temperatures below 40°F, there may be precipitation. Check for crystallization. If evident,warm to 80OF and thoroughly mix before using. DO NOT USE OPEN FLAME. Keep container tightly scaled In case of spill or leakage,soak up with an absorbent material such as sand, sawdust,fuller's earth,etc. Dispose of with chemical waste. .................................................................................................................................................................................................................................................... SECTION X- WASTE DISPOSAL METHODS .................................................................................................................................................................................................................................................... PESTICIDE DISPOSAL Wastes resulting from the use of this product may be disposed of on site or at an approved waste disposal facility. CONTAINER DISPOSAL Triple rinse(or equivalent). Then offer for recycling or reconditioning,or puncture and dispose of in a sanitary landfill or by other procedures approved by State and local authorities. .................................................................................................................................................................................................................................................... SECTION M-ADDITIONAL PRECA UI70NS .................................................................................................................................................................................................................................................... Do not contaminate food, feed or water by storage or disposal. Harmful If swallowed,absorbed through skin or inhaled. Prolonged or frequently repeated skin contact may cause allergic reactions in some Individuals. Avoid contact with skin, eyes or clothing. Avoid breathing vapors. Wash thoroughly with soap and water after handling. Remove contaminated clothing and wash before reuse. This pesticide is extremely toxic to fish and aquatic invertebrates. Do not discharge effluent containing this product Into lakes, streams, ponds, estuaries, oceans, or public waters unless this product is specifically identified and addressed in an NI'DES pennit. Do not discharge effluent containing this product to sewer systems without previously notifying the sewage treatment plant authority. For guidance contact your State Water Board or Regional Office of the EPA. ................................................................................................................................................................................................................................................... SECTION MI- SARA TITLE III HAZARDS .................................................................................................................................................................................................................................................... This product has been reviewed according to the EPA'Hazard Categories'promulgated under Section 311 and 312 of the Superfund Amendment and Reauthorization Act of 1986(SARA Title 111)and is considered,under applicable definitions, to meet the following categories: Fire —Sudden Release of Pressure —Reactivity —Immediate Health Hazard (acute) —Delayed Health Hazard(chronic) _2LNot a SARA Title III Hazard HMIS Ratings: I -Health I -Flammability 0-Reactivity B-Personal Protection ................................................................................................................................................................................................................................................... SEG`Fi ON MH- COMMENTS .................................................................................................................................................................................................................................................... The information contained herein is believed to be accurate whether originating with Fairfield American Corporation or not. Fairfield American Corporation provides no warranties, either expressed or implied, and assumes no responsibility for the accuracy or completeness of the data.Recipients are advised to confirm any data, in advance of need, that it is current,applicable and suitable to their circumstances. .....................................................................................................................................................................................................t.............................................. SECTION MV-APPENDIX .................................................................................................................................................................................................................................................... MATERIAL SAFETY DATA SHEET PREPARED BY: REGULATORY DEPARTMENT DATE PREPARED: 2/12/91 EMERGENCY PHONE NUMBER: 201 -669-3696 I IMIS Hazard Index: Hazardous 4-Severe I -Slight Materials 3-Serious 0-Minimal Identification 2-Moderate System N/E NOT ESTABLISHED N/A *'**NOT APPLICABLE PERMANONE 31-66 70.12.070 Title 70 RCW: Public Health and Safety 70.12.070 Fund subject to audit and check by sta 0.14.040 Review of prospective rate setting m h- public health pool fund shall be subject to audit by a ods. he state agencies listed in *RCW 70.14.010 hall divi 'on of departmental audits and shall be subject to ch k review a feasibility of establishing prospective p ment by th state department of health. [1991 c 3 § 316; 19 c approach s within their health care programs. Wo plans 141 § 7; 1943 c 190 § 5; Rem. Supp. 1943 § 6099-5 or timeta les shall be prepared for the develo ment of prospectiv rates. The agencies shall identify egislative actions that ay be necessary to facilitate the doption of Chapter 70.14 prospective ra setting methods. [1986 c 30 § 9.] HEAL CARE SERVICES PURCHASE BY *Reviser's n e: RCW 70.14.010 was repealed b 1988 c 107§35, STATE AGENCIES effective October 1, 988. Sections 70.14.050 rug purchasing st controls- 70.14.020 State a encies to identify alternative health c providers. Establishment of d g formularies. (1) ach agency listed 70.14.030 Health a utilization review procedures. 70.14.040 Review prospective rate setting methods in *RCW 70.14.010 all individually o in Cooperation with 70.14.050 Drug purc sing cost controls—Establis nt of drug for- other agencies take a necessary ac ons to control costs mularie without reducing the q ity of care w en reimbursing for or State health care cost con inment Policies: RCW a .a1.i6o. purchasing drugs. To a omplish t purpose, each agency �' shall investigate the fear ility of d may establish a drug 70.14.020 State gencies to identify alternative formulary designating wlu h dru may be paid for through health care providers Each of th agencies listed in their health care programs. For urposes of this section, a *RCW 70.14.010, with th exception, of the department of drug formulary means a li o drugs, either inclusive or labor and industries, which xpends�flore than five hundred exclusive, that defines whic drugs are eligible for reim- thousand dollars annually f stato funds for purchase of bursement by the agency. health care shall identify the vail�6ility and costs of nonfee (2) In developing the d g ormulary authorized by this for service providers of hea h are, including preferred section, agencies: provider organizations, health aintenance organizations, (a) Shall prohibit r mburs ment for drugs that are managed health care or case a agement systems, or other determined to be ineffec ve by th United States food and nonfee for service alternative. I each case where feasible drug administration; in which an alternative heal, care rovider arrangement, of (b) Shall adopt ru s in order to nsure that less expen- similar scope and quality, ' availa a at lower cost than fee sive generic drugs wi be substituted r brand name drugs for service providers, s h state a encies shall make the in those instances w ere the quality care is not dimin- services of the alterna ve provide available to clients, ished; consumers, or employe s for whom s to dollars are spent to (c) Where po sible, may authorize imbursement for purchase health care As consistent ith other state and drugs only in ec omical quantities; federal law, require ents for copaym ts, deductibles, the (d) May li t the prices paid for dru by such means scope of available rvices, or other inc tives shall be used as central purc asing, volume contracting, setting maxi- to encourage clie Is, consumers, or em loyees to use the mum prices t be paid; lowest cost provi ers, except that copaym nts or deductibles (e) Shal consider the approval of drug with lower shall not be re ired where they might h ve the impact of abuse pote ial in substitution for drugs wit significant denying acces to necessary health care in timely manner. abuse pote tial; and [1986 c 303 7.1 (f) y take other necessary measures to co trol costs *Reviser' note: RCW 70.14.010 was repealed 1988 c 107§35, of drugs ithout reducing the quality of care. effective Octo er 1, 1988. (3) gencies may provide for reasonable exce ions to Medical assi ance Agreements with managed health ca systems: RCW the d formulary required by this section. 74.09. z. ( Agencies may establish medical advisory co mit- tees, r utilize committees already established, to assl t in 70. 4.030 Health care utilization review ocedures. the evelopment of the drug formulary required by is Plans r establishing or improving utilizati review se 'on. [1986 c 303 § 10.1 proce ures for purchased health care services shall be *Reviser's note: RCW 70.14.010 was repealed by 1988 c 107§3 devel ped by each agency listed in *RCW 70.14.0 0. The fective October 1, 1988. plan shall specifically address such utilization eview pro edures as prior authorization of services, h pital Chapter 70.22 in tient length of stay review, requirements for e of o atient surgeries and the obtaining of second opinion for MOSQUITO CONTROL s rgeries, review of invoices or claims submitted by se 'ce roviders, and performance audit of providers. [1986 c 3 sections 8 ] 70.22.005 Transfer of duties to the department of health. 70.22.010 Declaration of purpose. *Reviser's note: RCW 70.14.010 was repealed by 1988 c 107§35, 70.22.020 Secretary may make inspections, investigations, and determi- effective October 1, 1988. nations and provide for control. 70.22.030 Secretary to coordinate plans. [Title 70 RCW—page 16] (1992 Ed.) PIP- Title 70 RCW: Public Health and Safety Chapter 70.22 70.22.040 Secretary may contract with,receive funds from entities and 70.22.050 Powers and duties of secretary. To Carry individuals—Authorization for governmental entities to out the purpose of this chapter, the secretary of health may: contract,grant funds,levy taxes. (1) Abate as nuisances breeding places for mosquitoes 70.22.050 Powers and duties of secretary. 70.22.060 Governmental entities to cooperate with secretary. as defined in RCW 17.28.170; 70.22.900 Severability-1961 c 283. (2) Acquire by gift, devise, bequest, lease, or purchase, real and personal property necessary or convenient for 70.22.005 Transfer of duties to the department of carrying out the purpose of this chapter; health. The powers and duties of the secretary of social and (3) Make contracts, employ engineers, health officers, health services under this chapter shall be performed by the sanitarians, physicians, laboratory personnel, attorneys, and secretary of health. [1989 1st ex.s. c 9 § 246.1 other technical or professional assistants, Effective date—Severability-1989 1st ex.s. c 9: See RCW (4) Publish information or literature; and 43.70.910 and 43.70.920. (5) Do any and all other things necessary to carry out the purpose of this chapter: PROVIDED, That no program 70.22.010 Declaration of purpose. The purpose of shall be permitted nor any action taken in pursuance thereof this chapter is to establish a state-wide program for the which may be injurious to the life or health of game or fish. control or elimination of mosquitoes as a health hazard. [1991 c 3 § 320; 1989 c 11 § 25; 1979 c 141 § 91; 1961 c [1961 c 283 § 1.1 283 § 5.1 Mosquito control districts: Chapter 17.28 RCW. Severability-1989 c 11: See note following RCW 9A.56.220. 70.22.020 Secretary may make inspections, investi- 70.22.060 Governmental entities to cooperate with gations,and determinations and provide for control. The secretary. Each state department, agency, and political secretary of health is hereby authorized and empowered to subdivision shall cooperate with the secretary of health in make or cause to be made such inspections, investigations, carrying out the purposes of this chapter. [1991 c 3 § 321; studies and determinations as he or she may from time to 1979 c 141 § 92; 1961 c 283 § 6.] time deem advisable in order to ascertain the effect of mosquitoes as a health hazard, and, to the extent to which 70.22.900 Severability-1961 c 283. If any provision funds are available, to provide for the control or elimination of this act, or its application to any person or circumstance thereof in any or all parts of the state. [1991 c 3 § 317; is held invalid, the remainder of the act, or the application of 1979 c 141 § 88; 1961 c 283 § 2.] the provision to other persons or circumstances is not affected. [1961 c 283 § 7.] 70.22.030 Secretary to coordinate plans. The secretary of health shall coordinate plans for mosquito \Trans hapter 70.24 control work which may be projected by any county, city or i town, municipal corporation, taxing district, state department L AND TREATMENT OF SEX LLY i or agency, federal government agency, or any person, groupTRANSMITTED DISEASES or organization, and arrange for cooperation between any : Control and treatment of venerea diseases) i such districts, departments, agencies, persons, groups or Se organizations. [1991 c 3 § 318; 1979 c 141 § 89; 1961 c 70ns r of duties to the department health. 283 § 3.] 70islat a finding.70finition70.22.040 Secretary may contract with, receive 70rviews, amination,couns ng,or treatment of infected persons or rsons believ to be infected— funds from entities and individuals—Authorization for Disseminatio of false" formation—Penalty. governmental entities to Contract, grant funds, levy taxes. 70.24.024 Orders for examina ons d counseling—Restrictive mea- 1 The secretary of health is authorized and empowered to sures—Investigat Issuance of order Confidential receive funds from any county, city or town, municipal notice and heann xception. corporation, taxing district, the federal government, or any 70.24.034 Detention—Ground r r—Hearing. 70.24.050 Diagnosis of sexu y trans tted diseases--Confirmation— person, group or organization to carry out the purpose of this Anonymous revalence r orts. chapter. In connection therewith the secretary is authorized 70.24.070 Detention and eatment faciliti and empowered to contract with any such county, city, or 70.24.080 Penalty. town, municipal corporation, taxing district, the federal 70.24.084 Violations chapter—Aggrieved rsons—Right of action. 70.24.090 Pregnant omen—Test for syphilis. government, person, group or organization with respect to 70.24.095 Pregna women—Drug treatment pro to participants— the construction and maintenance of facilities and other work A S counseling. for the purpose of effecting mosquito control or elimination, 70.24.100 Syp is laboratory tests. and any such county, city or town, municipal corporation, or 70.24.105 Di losure of HIV antibody test or testing o reatment of sexually transmitted diseases—Exchange medical taxing district obligated to carry out the provisions of any information. such contract entered into with the secretary is authorized, 70.24.110 Minors—Treatment,consent, liability for paymen or care. empowered and directed to appropriate, and if necessary, to 70.24.1 Sexually transmitted disease case investigators—A ority to levy taxes for and pay over such funds as its contract with withdraw blood. the secretary may from time to time require. [1991 C 3 § 70.2 .125 Reporting requirements for sexually transmitted disease Rules. 319; 1979 c 141 § 90; 1961 c 283 § 4.] .24.130 Adoption of rules. (1992 Ed) [Title 70 RCW—page 171 17.24.210 Title 17 RCW: Weeds, Rodents and Pests 7.24.200 shall be identified on a list app ed by the 17.28.330 Annexation of territory authorized—Petition—Hearing— ! dir .or. For the purposes of this section, person on the Boundaries. (F 17.28.340 Annexation of territory authorized—Order of annexation— list s la a known, for the duration of person's services Ii Election. C` under the p ram, as "an emerge measures worker." 17.28.350 Annexation of territory authorized—Filing of order— (1982 c 153 § Composition of board. 'Reviser's note: W 17.24.2 was repealed by 1991 c 257§23. 17.28360 Consolidation of districts—initial proceedings. 17.28.370 Consolidation of districts—Concurrent resolution. Severability-1982 53• If any provision of this act or its 17.28.380 Consolidation of districts—Election. application to any person or cir tance is held invalid,the remainder of 17.28.390 Consolidation of districts--0rder of consolidation. the act or the application of pro 'on to other persons or circumstances 17.28.400 Consolidation of districts—Composition of board. is not affected." [1982 c 1 § 5.1 17.28.410 Consolidation of districts—Powers of consolidated district— Effective date-1 c 153: "This ac ' necessary for the immediate Indebtedness of former districts. preservation of the p lic peace, health, or sa or support of the state 17.28.420 Dissolution—Election. government and i xisting public institutions,an hall take effect April 17.28.430 Dissolution—Result of election to be certified--Certificate 1, 1982." [1982 153 § 7.] of dissolution. 17.28.440 Dissolution—Disposition of property. 17.28.450 Dissolution—Collection of taxes to discharge indebtedness. 17 .900 Captions not law-1991 a 257. tions 17.28.900 severabiliry-1957 c 153. as use in RCW 17.24.005 through 17.24.171 constit no Special purpose districts, expenditures to recruit job candidates: RCW i part f the law. [1991 c 257 § 24.] 42.24.170. ` Chapter 17.28 17.28.010 Definitions. When used in this chapter, the MOSQUITO CONTROL DISTRICTS following terms, words or phrases shall have the following meaning: Sections (I) "District" means any mosquito control district 17.28.010 Definitions. formed pursuant to this chapter. 17.28.020 Districts may be organized in counties—Petition,present- (2) "Board" or "district board" means the board of l ment,signatures. trustees governing the district. 17.28.030 Petition method—Description of boundaries—Verification of (3) "County commissioners" means the governing body signatures—Resolution to include city. Of the COUrity. 17.28.040 Petition method—Publication of petition and notice of meet- ing. (4) "Unit" means all unincorporated territory in a 17.28.050 Resolution method. proposed district in one county, regarded as an entity, or 17.28.060 Hearing—Defective petition—Establishment of boundaries. each C1[y in a proposed district, likewise regarded as an 17.28.070 Procedure to include other territory. entity. +' 17.28.080 Determination of public necessity and compliance with y chapter. (5) "Territory" means any city or county or portion of 17.28.090 Declaration establishing and naming district—Election to either or both city or county having a population of not less form district—Establishment of district. than one hundred persons. 17.28.100 Election on proposition to levy tax. (6) "Person" means any individual, firm, partnership, 17.28.110 Board of trustees—Composition. corporation, company, association, or joint stock association, 17.28.120 Board of trustees—Name of board—Qualification of mem- bers. and the legal successor thereof. [1957 c 153 § 1.1 17.28.130 Board of trustees—Terms—Vacancies. 17.28.140 Board of trustees—Organization--Officers— 17.28.020 Districts may be organized in counties— Compensation—Expenses. y 17.28.150 Board of trustees—Meetings—Rules—Quorum. Petition, presentment,signatures. Any number of units of j� 17.28.160 Powers of district. a territory within the state of Washington in Adams, Benton, 17.28.170 Mosquito breeding places declared public nuisance— Franklin, Grant, Kittitas, Walla Walla and Yakima counties Abatement. or any other county may be organized as a mosquito control 17.28.175 Control of mosquitos—Declaration that owner is responsi- ble. district I n v' S under the provisions of this chapter. 17.28.185 Control of mosquitos—Noncompliance by landowner with A petition to form a district may consist of any number regulations. of separate instruments which shall be presented at a regular 17.28.250 Interference with entry or work of district—Penalty. meeting of the county commissioners of the county in which 17.28.251 Borrowing money or issuing warrants in anticipation of the eater area of the proposed district is located. Petitions revenue. P Po r 17.28.252 Excess levy authorized. shall be signed by registered voters of each unit of the 17.28.253 District boundaries for tax purposes. proposed district, equal in number to not less than ten 17.28.254 Abatement,extermination declared necessity and benefit to percent of the votes cast in each unit respectively for the i, land. office of governor at the last gubernatorial election prior to ill 17.28.255 Classification of property—Assessments. 17.28.256 Assessments—Roll,hearings,notices,objections,appeal, the time of presenting the petition. [1969 c 96 § 1; 1957 c etc. 153 § 2.1 17.28.257 Assessments—Payment,lien,delinquencies, foreclosure,etc. 17.28.258 County treasurer—Duties. 17.28.260 General obligation bonds—Excess property tax levies. 17.28.030 Petition method—Description of bound- 17.28.270 Collection,disposition,of revenue—Depository. aries—Verification of signatures—Resolution to include 17.28.280 Withdrawal of funds. city. Before a city can be included as a part of the proposed 17.28.290 Matching funds. district its governing body shall have requested that the city 17.28.310 Expenses of special elections. be included by resolution, duly authenticated. 17.28.310 Annual certification of assessed valuation. 17.28.320 Annexation of territory authorized—Consent by city. [Title 17 RCW—page 361 (1992 Ed.) Title 17 RCW: Weeds, Rodents and Pests 17.28.030 The petition shall set forth and describe the boundaries No defect in the contents of the petition or in the title of the proposed district and it shall request that it be orga- to or form of the notice or signatures, or lack of signatures nized as a mosquito control district. Upon receipt of such a thereto, shall vitiate any proceedings if the petition has a petition, the auditor of the county in which the greater area sufficient number of qualified signatures. of the proposed district is located shall be charged with the On the final hearing the county commissioners shall responsibility of examining the same and certifying to the make such changes in the proposed boundaries as are sufficiency of the signatures thereon. For the purpose of advisable, and shall define and establish the boundaries. examining the signatures on such petitions, the auditor shall [1957 c 153 § 6.] be permitted access to the voters' registration books of each city and county located in the proposed district and may 17.28.070 Procedure to include other territory. If appoint the respective county auditors and city clerks thereof the county commissioners deem it proper to include any as his deputies. No person may withdraw his name from a territory not proposed for inclusion within the proposed petition after it has been filed with the auditor. Within thirty boundaries, they shall first cause notice of intention to do so days following the receipt of such petition, the auditor shall to be mailed to each owner of land in the territory whose transmit the same to the board of commissioners of the name appears as owner on the last completed assessment roll county in which the greater area of the proposed district is of the county in which the territory lies, addressed to the located, together with his certificate as to the sufficiency owner at his address given on the assessment roll, or if no thereof. [1957 c 153 § 3.] address is given, to his last known address; or if it is not known, at the county seat of the county in which his land 17.28.040 Petition method—Publication of petition lies. The notice shall describe the territory and shall fix a and notice of meeting. Upon receipt of a duly certified time, not less than two weeks from the date of mailing, petition, the board of commissioners shall cause the text of when all persons interested may appear before the county the petition to be published once a week for at least three commissioners and be heard. consecutive weeks in one or more newspapers of general The boundaries of a district lying in a city shall not be circulation within the county where the petition is presented altered unless the governing board of the city, by resolution, and at each city a portion of which is included in the consents to the alteration. [1957 c 153 § 7.] proposed district. If any portion of the proposed district lies in another county, the petition and notice shall be likewise 17.28.080 Determination of public necessity and published in that county. compliance with chapter. Upon the hearing of the petition Only one copy of the petition need be published even the county commissioners shall determine whether the public though the district embraces more than one unit. No more necessity or welfare of the proposed territory and of its than five of the names attached to the petition need appear inhabitants requires the formation of the district, and shall in the publication of the petition and notice, but the number also determine whether the petition complies with the of signers shall be stated. provisions of this chapter, and for that purpose shall hear all With the publication of the petition there shall be competent and relevant testimony offered. [1957 c 153 § 8.] published a notice of the time of the meeting of the county commissioners when the petition will be considered, stating 17.28.090 Declaration establishing and naming that all persons interested may appear and be heard. [1957 district—Election to form district—Establishment of c 153 § 4.] district. If, from the testimony given before the county commissioners, it appears to that board that the public 17.28.050 Resolution method. Such districts may necessity or welfare requires the formation of the district, it also be organized upon the adoption by the county commis- shall, by an order entered on its minutes, declare that to be sioners of a resolution of intention so to do, in lieu of the its finding, and shall further declare and order that the procedure hereinbefore provided for the presentation of territory within the boundaries so fixed and determined be petitions. In the event the county commissioners adopt a organized as a district, under an appropriate name to be resolution of intention, such resolution shall describe the selected by the county commissioners, subject to approval of boundaries of the proposed district and shall set a time and the voters of the district as hereinafter provided. The name place at which they will consider the organization of the shall contain the words "mosquito control district." district, and shall state that all persons interested may appear At the time of the declaration establishing and naming and be heard. Such resolution of intention shall be published the district, the county commissioners shall by resolution call in the same manner and for the same length of time as a a special election to be held not less than thirty days and not petition. [1957 c 153 § 5.] more than sixty days from the date thereof, and shall cause to be published a notice of such election at least once a 17.28.060 Hearing—Defective petition— week for three consecutive weeks in a newspaper of general Establishment of boundaries. At the time stated in the circulation in the county, setting forth the hours during notice of the filing of the petition or the time mentioned in which the polls will be open, the boundaries of the proposed the resolution of intention, the county commissioners shall district as finally adopted, and the object of the election. If consider the organization of the district and hear those any portion of the proposed district lies in another county, a appearing and all protests and objections to it. The commis- notice of such election shall likewise be published in that sioners may adjourn the hearing from time to time, not county. exceeding two months in all. (1992 Ed.) [Title 17 RCW—page 37] 17.28.090 Title 17 RCW: Weeds, Rodents and Pests The election on the formation of the mosquito control ,ONE YEAR . . . . . . CENTS PER district shall be conducted by the auditor of the county in THOUSAND DOLLARS OF ASSESSED VALUE LEVY which the greater area of the proposed district is located in "Shall the mosquito control district, if formed, levy a accordance with the general election laws of the state and general tax of. . . . . . cents per thousand dollars of assessed the results thereof shall be canvassed by that county's value for one year upon all the taxable property within said canvassing board. For the purpose of conducting an election district in excess of the constitutional and/or statutory tax under this section, the auditor of the county in which the limits for authorized purposes of the district? greater area of the proposed district is located may appoint the auditor of any county or the city clerk of any city lying YES • • • • • • • • • • • • • • • • • • • • • • • • • • • wholly or partially within the proposed district as his NO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . deputies. No person shall be entitled to vote at such election Such proposition to be effective must be approved by a unless he is a qualified voter under the laws of the state in majority of at least three-fifths of the persons voting on the effect at the time of such election and has resided within the proposition to levy such tax in the manner set forth in mosquito control district for at least thirty days preceding the Article VII, section 2(a) of the Constitution of this state, as date of the election. The ballot proposition shall be in amended by Amendment 59 and as thereafter amended. substantially the following form: [1982 c 217 § 1; 1973 1st ex.s. c 195 § 2; 1957 c 153 § 10.1 "Shall a mosquito control district be established for the Severability—Effective dates and termination dates— area described in a resolution of the board of commissioners Constriction-1973 lst ex s.c 195: See notes following RCW 84.52.043. of . . . . . . county adopted on the . . . . day of . . . . . .. 19. . .? 17.28.110 Board of trustees—Composition. Within thirty days after the filing with the secretary of state of the YES • • . . . . . . . . . • . . • . . . . . . . . . • . . • . certified copy of the order of formation, a governing board NO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . of trustees for the district shall be appointed. The district If a majority of the persons voting on the proposition board shall be appointed as follows: shall vote in favor thereof, the mosquito control district shall (1) If the district is situated in one county only and thereupon be established and the county commissioners of consists wholly of unincorporated territory, five members the county in which the greater area of the district is situated shall be appointed by the county commissioners of the shall immediately file for record in the office of the county county. auditor of each county in which any portion of the land (2) If the district is situated entirely in one county and embraced in the district is situated, and shall also forward to includes both incorporated and unincorporated territory one the county commissioners of each of the other counties, if member shall be appointed from each commissioner district any, in which any portion of the district is situated, and also lying wholly or partly within the district by the county shall file with the secretary of state, a certified copy of the commissioners of the county, and one member from each order of the county commissioners. From and after the date city, the whole or part of which is situated in the district, by of the filing of the certified copy with the secretary of state, the governing body of the city; but if the district board the district named therein is organized as a district, with all created consists of less than five members, the county the rights, privileges, and powers set forth in this chapter, or commissioners shall appoint from the district at large enough necessarily incident thereto. additional members to make a board of five members. If a majority of the persons voting on the proposition (3)If the district is situated in two or more counties and shall vote in favor thereof, all expenses of the election shall is comprised wholly of incorporated territory, one member be paid by the mosquito control district when organized. If shall be appointed from each commissioner district of each the proposition fails to receive a majority of votes in favor, county or portion of a county situated in the district by the the expenses of the election shall be borne by the respective county commissioners; but if the district board created counties in which the district is located in proportion to the consists of less than five members, the county commission- number of votes cast in said counties. [1957 c 153 § 9.] ers of the county in which the greater area of the district is situated shall appoint from the district at large enough 17.28.100 Election on proposition to levy tax. At additional members to make a board of five members. the same election there shall be submitted to the voters (4) If the district is situated in two or more counties and residing within the district, for their approval or rejection, a consists of both incorporated and unincorporated territory, proposition authorizing the mosquito control district, if one member shall be appointed by the county commissioners formed, to levy at the earliest time permitted by law on all of each of the counties from that portion of the district lying taxable property located within the mosquito control district within each commissioner district within its jurisdiction; and a general tax, for one year, of up to twenty-five cents per one member from each city, a portion of which is situated in thousand dollars of assessed value in excess of any constitu- the district by the governing body of the city; but if the tional_or statutory limitation for authorized purposes of the board created consists of less than five members, the county mosquito control district. The proposition shall be expressed commissioners in which the greater area of the district is on the ballots in substantially the following form: situated shall appoint from the district at large enough additional members to make a board of five members. [1959 c 64 § 1; 1957 c 153 § 11.] [Title 17 RCW—page 381 (1992 Ed.) Title 17 RCW: Weeds, Rodents and Pests 17.28.120 17.28.120 Board of trustees—Name of board— (1)Take.all necessary or proper steps for the extermina- Qualification of members. The district board shall be tion of mosquitoes. called "The board of trustees of . . . . . . mosquito control (2) Subject to the paramount control of the county or district." city in which they exist, abate as nuisances all stagnant pools Each member of the board appointed by the governing of water and other breeding places for mosquitoes. body of a city shall be an elector of the city from which he (3) If necessary or proper, in the furtherance of the is appointed and a resident of that portion of the city which objects of this chapter, build, construct, repair, and maintain is in the district. necessary dikes, levees, cuts, canals, or ditches upon any Each member appointed.from a county or portion of a land, and acquire by purchase, condemnation, or by other county shall be an elector of the county and a resident of lawful means, in the name of the district, any lands, rights that portion of the county which is in the district. of way, easements, property, or material necessary for any Each member appointed at large shall be an elector of of those purposes. the district. [1957 c 153 § 12.1 (4) Make contracts to indemnify or compensate any owner of land or other property for any injury or damage 17.28.130 Board of trustees—Terms—Vacancies. necessarily caused by the use or taking of property for dikes, The members of the first board in any district shall classify levees, cuts, canals, or ditches. themselves by lot at their first meeting so that: (5) Enter upon without hindrance any lands within the (1) If the total membership is an even number, the terms district for the purpose of inspection to ascertain whether of one-half the members will expire at the end of one year, breeding places of mosquitoes exist upon such lands; or to and the terms of the remainder at the end of two years, from abate public nuisances in accordance with this chapter; or to the second day of the calendar year next succeeding their ascertain if notices to abate the breeding of mosquitoes upon appointment. such lands have been complied with; or to treat with oil or (2)If the total membership is an odd number, the terms other larvicidal material any breeding places of mosquitoes of a bare majority of the members will expire at the end of upon such lands. one year, and the terms of the remainder at the end of two (6) Sell or lease any land, rights of way, easements, years, from the second day of the calendar year next property or material acquired by the district. succeeding their appointment. (7) Issue warrants payable at the time stated therein to The term of each subsequent member is two years from evidence the obligation to repay money borrowed or any and after the expiration of the term of his predecessor. other obligation incurred by the district, warrants so issued In event of the resignation, death, or disability of any to draw interest at a rate fixed by the board payable annually member, his successor shall be appointed by the governing or semiannually as the board may prescribe. body which appointed him. [1957 c 153 § 13.] (8)Make contracts with the United States, or any state, municipality, or any department of those entities for carrying 17.28.140 Board of trustees—Organization— out the general purpose for which the district is formed. Officers—Compensation—Expenses. The members of the (9) Acquire by gift, devise, bequest, lease, or purchase, first district board shall meet on the first Monday subsequent real and personal property necessary or convenient for its to thirty days after the filing with the secretary of state of purposes. (10) Make contracts, employ engineers, health officers, the certificate of incorporation of the district. They shall sanitarians, physicians, laboratory personnel, attorneys, and organize by the election of one of their members as president and one secretary. other technical or professional assistants; and publish The members of the district board shall serve without information or literature and do any and all other things compensation; but the necessary expenses of each member necessary or incident to the powers granted by, and to carry out the projects specified for actual traveling in connection with meetings or business in this chapter. [1981 c 156 § 1; 1957 c 153 § 16.] of the board may be allowed and paid. The secretary shall receive such compensation as shall be fixed by the district board. [1957 c 153 § 14.1 17.28.170 Mosquito breeding places declared public nuisance—Abatement. Any breeding place for mosquitoes 17.28.150 Board of trustees—Meetings—Rules— Which exists by reason of any use made of the land on Quorum. The district board shall provide for the time and Which it is found or of any artificial change in its natural place of holding its regular meetings, and the manner of condition is a public nuisance: PROVIDED,That conditions calling them, and shall establish rules for its proceedings. or usage of land which are beyond the control of the Special meetings may be called by three members, landowner or are not contrary to normal, accepted practices notice of which shall be given to each member at least of water usage in the district, shall not be considered a twenty-four hours before the meeting. public nuisance. All of its sessions, whether regular or special, shall be The nuisance may be abated in any action or proceed- open to the public. ing, or by any remedy provided by law. [1959 c 64 § 2; A majority of the members shall constitute a quorum for 1957 c 153 § 17.] the transaction of business. [1957 c 153 § 15.] 17.28.175 Control of mosquitos—Declaration that 17.28.160 Powers of district. A mosquito control owner is responsible. A board established pursuant to district organized under this chapter may: RCW 17.28.110 may adopt, by resolution, a policy declaring ] (1992 Ed.) [Title 17 RCW—page 39] 17.28.175 Title 17 RCW: Weeds, Rodents and Pests that the control of mosquitos within the district is the in excess of the constitutional and/or statutory limitations for responsibility of the owner of the land from which the any of the authorized purposes of such district, not in excess mosquitos originate. To protect the public health or welfare, of fifty cents per thousand dollars of assessed value per year the board may, in accordance with policies and standards when authorized so to do by the electors of such district by established by the board following a public hearing, adopt a a three-fifths majority of those voting on the proposition in regulation requiring owners of land within the district to the manner set forth in Article VII, section 2(a) of the perform such acts as may be necessary to control mosquitos. Constitution of this state, as amended by Amendment 59 and (1990 c 300 § 2.J as thereafter amended at such time as may be fixed by the board of trustees for the district, which special election may 17.28.185 Control of mosquitos—Noncompliance by be called by the board of trustees of the district, at which landowner with regulations. (1) Whenever the board finds special election the proposition of authorizing such excess that the owner has not taken prompt and sufficient action to levy shall be submitted in such form as to enable the voters comply with regulations adopted pursuant to RCW 17.28.175 favoring the proposition to vote "Yes" and those opposing to control mosquitos originating from the owner's land, the thereto to vote "No". Nothing herein shall be construed to board shall notify the owner that a violation of this chapter prevent holding the foregoing special election at the same exists. The notice shall be in writing and sent by certified time as that fixed for a general election. [1973 1 st ex.s. c j mail, or served by personal service. The notice shall provide 195 § 3, 1959 c 64 § 4.1 a reasonable time period for action to be taken to control Severability—Effective dates and termination dates— mosquitos. If the board deems that a public nuisance or Construction-1973 1st ex.s.c 195: See notes following RCW 84.52.043, threat to public health or welfare caused by the mosquito infestation is sufficiently severe, it may require immediate 17.28.253 District boundaries for tax purposes. For control action to be taken within forty-eight hours following the purpose of property taxation and the levying of property the time that notification is reasonably expected to have been taxes the boundaries of the mosquito control district shall be ! received by the owner or agent by certified mail or personal the established official boundary of such district existing on service. the first day of September of the year in which the levy is (2) If the owner does not take sufficient action to made, and no such levy shall be made for any mosquito control mosquitos in accordance with the notice, the board control district whose boundaries are not duly established on may control them, or cause their being controlled, at the the first day of September of such year. [1959 c 64 § 5.] expense of the owner. The amount of such expense shall constitute a lien against the property and may be enforced by 17.28.254 Abatement, extermination declared proceedings on such lien. The owner shall be liable for necessity and benefit to land. It is hereby declared that payment of the expenses, and nothing in this chapter shall be whenever the public necessity or welfare has required the construed to prevent collection of any judgment on account formation of a mosquito control district, the abatement or thereof by any means available pursuant to law, in substitu- extermination of mosquitoes within the district is of direct, tion for enforcement of the lien. Necessary costs and economic benefit to the land located within such district and expenses, including reasonable attorneys' fees, incurred by is necessary for the protection of the public health, safety the board in carrying out this section, may be recovered at and welfare of those residing therein. [1959 c 64 § 6.] the same time, as a part of the action filed under this section. The venue in proceedings for reimbursement of expenses 17.28.255 Classification of property—Assessments. brought pursuant to this section, including those involving The board of trustees shall annually determine the amount of governmental entities, shall be the county in which the real money necessary to carry on the operations of the district property that is the subject of the action is situated. [1990 and shall classify the property therein in proportion to the c 300 § 3.1 benefits to be derived from the operations of the district and in accordance with such classification shall apportion and 17.28.250 Interference with entry or work of assess the several lots, blocks, tracts, and parcels of land or district—Penalty. Any person who obstructs, hinders, or other property within the district, which assessment shall be interferes with the entry upon any land within the district of collected with the general taxes of the county or counties. any officer or employee of the district in the performance of [1959 c 64 § 7.] his duty, and any person who obstructs, interferes with, molests, or damages any work performed by the district, is 17.28.256 Assessments—Roll, hearings, notices, guilty of a misdemeanor. [1957 c 153 § 25.1 objections, appeal, etc. The board of trustees in assessing the property within the district and the rights, duties and 17.28.251 Borrowing money or issuing warrants in liabilities of property owners therein shall be governed, anticipation of revenue. A mosquito control district may, insofar as is consistent with this chapter, by the provisions prior to the receipt of taxes raised by levy, borrow money or for county road improvement districts as set forth in RCW issue warrants of the district in anticipation of revenue, and 36.88.090 through 36.88.110. [1959 c 64 § 8.] such warrants shall be redeemed from the first money available from such taxes. [1959 c 64 § 3.1 17.28.257 Assessments—Payment, lien, delinquen- cies, foreclosure, etc. The provisions of RCW 36.88.120, 17.28.252 Excess levy authorized. A mosquito 36.88.140, 36.88.150, 36.88.170 and 36.88.180 governing the control district shall have the power to levy additional taxes liens, collection, payment of assessments, delinquent assess- [Title 17 RCW—page 40] (1992 Ed_) Title 17 RCW: Weeds, Rodents and Pests 17.28.257 ments, interest and penalties, lien foreclosure and foreclosed district board settle with the district board and pay over to property of county road improvement districts shall govern the treasurer of the county where the district is organized all such matters as applied to mosquito control districts. [1959 money in their possession belonging to the district. The last c 64 § 9.1 named treasurer shall give a receipt for the money and place it to the credit of the district. [1957 c 153 § 27.] 17.28.258 County treasurer—Duties. The county treasurer shall collect all mosquito control district assess- 17.28.280 Withdrawal of funds. The funds shall ments, and the duties and responsibilities herein imposed only be withdrawn from the county treasury depository upon upon him shall be among the duties and responsibilities of the warrant of the district board signed by its president or his office for which his bond is given as county treasurer. acting president, and countersigned by its secretary. [1957 The collection and disposition of revenue from such assess- c 153 § 28.] ments and the depositary thereof shall be the same as for tax revenues of such districts as provided in RCW 17.28.270. 17.28.290 Matching funds. Any part or all of the [1959 c 64 § 10.] taxes collected for use of the district may be used for matching funds made available to the district by county, 17.28.260 General obligation bonds—Excess state, or federal governmental agencies. [1957 c 153 § 29.] property tax levies. A mosquito control district shall have the power to issue general obligation bonds and to pledge 17.28.300 Expenses of special elections. All expens- the full faith and credit of the district to the payment thereof, es of any special election conducted pursuant to the provi- for authorized capital purposes of the mosquito control sions of this chapter shall be paid by the mosquito control district, and to provide for the retirement thereof by excess district. [1957 c 153 § 30.] property tax levies whenever a proposition authorizing both the issuance of such bonds and the imposition of such excess 17.28.310 Annual certification of assessed valuation. levies has been approved by the voters of the district, at an It shall be the duty of the assessor of each county lying election held pursuant to RCW 39.36.050, by three-fifths of wholly or partially within the district to certify annually to the persons voting on said proposition at said election at the board the aggregate assessed valuation of all taxable which such election the total number of persons voting on property in his county situated in any mosquito control such bond proposition shall constitute not less than forty district as the same appears from the last assessment roll of percent of the total number of votes cast within the area of his county. [1957 c 153 § 31.] said mosquito control district at the last preceding county or state general election. Mosquito control districts may become indebted for capital purposes up to an amount equal 17.28.320 Annexation of territory authorized— to one and one-fourth percent of the value of the taxable Consent city. Any territory contiguous to a district may property in the district, as the term "value of the taxable be annexedd the district. property" is defined in RCW 39.36.015. If the territory itory to be annexed is in a city, consent to the Such bonds shall never be issued to run for a longer annexation shall first be obtained from the governing body of the city. An authenticated copy of the resolution or order period than ten years from the date of issue and shall be issued and sold in accordance with chapter 39.46 RCW. of that body consenting to the annexation shall be attached [1984 c 186 § 5; 1983 c 167 § 18; 1973 1st ex.s. c 195 § 4; to the annexation petition. [1957 c 153 § 32.] 1970 ex.s. c 56 § 5; 1969 ex.s. c 232 § 65; 1957 c 153 § 26.1 17.28.330 Annexation of territory authorized— Purpose-1984 c 186: See note following RCW 39.46.110. Petition—Hearing—Boundaries. The district board, upon receivinga written petition for annexation containing a Liberal construction—Severability-1983 c 167: See RCW 39.46.010 and note following, description of the territory sought to be annexed, signed by Severability—Effective dates and termination dates— registered voters in said territory equal in number to at least Construction-1973 1st ex.s.c 195: See notes following RCW 84.52.043. ten percent of the number of votes cast in the territory for Purpose-1970 ex.s.c 56: See note following RCW 39.52.020. the office of governor at the last gubernatorial election prior Validation— Saving—Severability-1969 ex.s.c 232: See notes to the time the petition is presented, shall set the petition for following RCW 39.52.020. hearing. It shall publish notice of the hearing along with a copy of the petition, stating the time and place set for the 17.28.270 Collection, disposition, of revenue— hearing, in each county in which any part of the district or Depository. All taxes levied under this chapter shall be of the territory is situated, and in each city situated wholly computed and entered on the county assessment roll and or in part in the territory. Not more than five of the names collected at the same time and in the same manner as other attached to the petition need appear in the publication, but county taxes. When collected, the taxes shall be paid into the number of signers shall be stated. the county treasury for the use of the district. At the time set for the hearing the district board shall If the district is in more than one county the treasury of hear persons appearing in behalf of the petition and all the county in which the district is organized is the depository protests and objections to it. The district board may adjourn of all funds of the district. the hearing from time to time, but not exceeding two months The treasurers of the other counties shall, at any time, in all. not oftener than twice each year, upon the order of the (1992 Ed) [Title 17 RCW—page 411 17.28.330 Title 17 RCW: Weeds, Rodents and Pests On the final hearing the district board shall make such The board of each district to which a proposal of changes as it believes advisable in the boundaries of the consolidation is sent shall consider said proposal and give territory, and shall define and establish the boundaries. It notice of its decision to the proposing board. [1957 c 153 shall also determine whether the petition meets the require- § 36.] ments of this chapter. [1957 c 153 § 33.] 17.28.370 Consolidation of districts—Concurrent 17.28.340 Annexation of territory authorized— resolution. Should it appear that two-thirds of the members Order of annexation—Election. If upon the hearing the of each of the boards of districts proposed to be consolidated district board finds that the petition and the proceedings favor consolidation each of said boards shall then, by a vote thereon meet the requirements of this chapter and that it is of not less than two-thirds of its members adopt a concurrent desirable and to the interests of the district and of the resolution in favor of consolidation, declaring its willingness territory proposed to be annexed that the territory, with to consolidate, specifying a name for the consolidated boundaries as fixed and determined by the district board, or district. Immediately upon the adoption of said concurrent any portion of it, should be annexed to the district, the board resolution a copy of same signed by not less than two-thirds shall order the boundaries of the district changed to include of the members of each board shall be forwarded to the the territory, or portion of the territory, subject to approval county commissioners of the county in which all of or a of the electors of the territory proposed to be annexed. The major portion of the land of all, the districts consolidated are election to be conducted and the returns canvassed and situated. [1957 c 153 § 37.] declared insofar as is practicable in accordance with the requirements of this chapter for the formation of a district. 17.28.380 Consolidation of districts—Election. The expenses of such election shall be borne by the mosqui- When the concurrent resolution for consolidation has been to control district regardless of the outcome of the election. adopted, each board of the districts proposed for consolida- The order of annexation shall describe the boundaries of tion shall forthwith call a special election in its district in the annexed territory and that portion of the boundary of the which shall be presented to the electors of the districts the district which coincides with any boundary of the territory. question whether the consolidation shall be effected. If necessary in making this order, the board may have any The election shall be conducted and the returns can- portion of the boundaries surveyed. vassed and declared insofar as is practicable in accordance If more than one petition for the annexation of the with the requirements of this chapter for the formation of a territory has been presented, the district board may in one district. order include in the district any number of separate territo- The board of each district shall declare the returns of ries. [1957 c 153 § 34.1 the election in its district, and shall certify the results to the county commissioners of the county in which all the dis- 17.28.350 Annexation of territory authorized— tricts, or the major portion of the land of all the districts, are Filing of order—Composition of board. The order of situated. [1957 c 153 § 38.] annexation shall be entered in the minutes of the board and certified copies shall be filed with the secretary of state and 17.28.390 Consolidation of districts—Order of with the county clerk and county auditor of each county in consolidation. Should not less than two-thirds of the votes which the district or any part of it is situated. of each of the respective districts proposed to be consolidat- From and after the date of the filing and recording of ed favor consolidation the county commissioners shall the certified copies of the order, the territory described in the immediately: order is a part of the district, with all the rights, privileges, (1) Enter an order on its minutes consolidating all of the and powers set forth in this act and those necessarily districts proposed for consolidation into one district with incident thereto. name as specified in the concurrent resolution. After the annexation of territory to a district, the district (2)Transmit a certified copy of the order to the county board shall consist of the number of members and shall be commissioners of any other county in which any portion of appointed in the manner prescribed by this chapter for a the consolidated district is situated. district formed originally with boundaries embracing the (3)Record a copy in the office of the county auditor of annexed territory. However, the members of the district each of the counties in which any portion of the consolidated board in office at the time of the annexation shall continue district is situated. to serve as members during the remainder of the terms for (4) File a copy in the office of the secretary of state. which they were appointed. [1957 c 153 § 35.] After the transmission, recording and filing of the order, the territory in the districts entering into the consolidation 17.28.360 Consolidation of districts—Initial pro- proposal forms a single consolidated district. [1957 c 153 § ceedings. Whenever in the judgment of the district board it 39.] is for the best interests of the district that it be consolidated with one or more other districts, it may, by a two-thirds vote 17.28.400 Consolidation of districts—Composition of its members, adopt a resolution reciting that fact and of board. After the consolidation, the board of the consoli- declaring the advisability of such consolidation and the dated district shall consist of the number and shall be willingness of the board to consolidate. The resolution shall appointed in the manner prescribed by this chapter for a be sent to the board of each district with which consolidation district originally formed. is proposed. [Title 17 RCW—page 421 (1992 Ed.) r k 4 Title 17 RCW: Weeds, Rodents and Pests 17.28.400 The terms of the members of the district boards of the ER, That any real property,easements,or rights of way vest several districts consolidated who are in office at the time of in the city in which they are situated or in the county in consolidation shall terminate at the time the consolidation which they are situated. [1957 c 153 § 44.1 becomes effective. [1957 c 153 § 40.] 17.28.450 Dissolution—Collection of taxes to 17.28.410 Consolidation of districts—Powers of discharge indebtedness. If, at the time of election to consolidated district—Indebtedness of former districts. dissolve, a district has outstanding any indebtedness, the vote The consolidated district has all the rights, powers, duties, to dissolve the district dissolves it for all purposes except the privileges and obligations of a district formed originally levy and collection of taxes for the payment of the indebted- under the provisions of this chapter. ness, and expenses of assessing,levying, and collecting such If at the time of consolidation there is outstanding an taxes. indebtedness of any of the former districts included in the Until the indebtedness is paid, the county commissioners consolidated district, that indebtedness shall be paid in the of the county in which the greater portion of the district was manner provided for the payment of indebtedness upon situated shall act as the ex offrcio district board and shall dissolution of a district. levy taxes and perform such functions as may be necessary A consolidated district shall not be liable for any in order to pay the indebtedness. [1957 c 153 § 45.1 indebtedness of any of the former districts included in it which was outstanding at the time of consolidation. 17.28.900 Severability-1957 c 153. If any part, or No property in any of the former districts shall be taxed parts, of this chapter shall be held unconstitutional, the to pay any indebtedness of any other former district existing remaining provisions shall be given full force and effect, as at the date of the consolidation. [1957 c 153 § 41.] completely as if the part held unconstitutional had not been included therein, if any such remaining part can then be 17.28.420 Dissolution—Election. The district may at administered in furtherance of the purposes of this chapter. any time be dissolved upon the vote of two-thirds of the [1957 c 153 § 46.] qualified electors in the district at a special election called by the district board upon the question. The question shall be Chapter 17.34 submitted as, "Shall the district be dissolved?", or words to PEST CONTROL COMPACT that effect. Notice of the election shall be published at least once a week for at least four weeks prior to the date of the election Section in a newspaper of general circulation in each county of the 17.34.01 Compact provisions. 17.34.020 Cooperation with insurance fund authori d. district. [1957 c 153 § 42.] 17.34.030 iling of bylaws and amendments. 17.34.040 ompact administrator. 17.28.430 Dissolution—Result of election to be 17.34.050 R uests or applications for assist from insurance fund. 17.14.060 A ncy incurring expenses to be dited with payments to certified—Certificate of dissolution. Should two-thirds or is state. more of the votes at the election favor dissolution the district 17.34.070 "Ex tive head"defined. board shall certify that fact to the secretary of state. Upon receipt of such certification the secretary of state shall issue 17.34.010 ompact pro isions. The pest control his certificate reciting that the district (naming it) has been compact is hereby acted into w and entered into with all dissolved, and shall transmit to and file a copy with the other jurisdiction leg ly joini therein in the form substan- county clerk of each county in which any portion of the tially as follows: district is situated. CLE I After the date of the certificate of the secretary of state, the district is dissolved. [1957 c 153 § 43.] INGS f t: find 17.28.440 Dissolution—Disposition of property. If The party states 1. In the abfindsenc of the igher degree of cooperation the district at the time of dissolution was wholly within among them possib under thi compact, the annual loss of unincorporated territory in one county, its property vests in approximately sev billion doll from the depredations of that county. pests is virtually ertain to contin , if not to increase. If the district at the time of dissolution was situated 2. Because f varying climatic, eographic and econom- wholly within the boundaries of a single city, its property is factors, eac state may be affecte ifferently by particu- vests in that city. lar species f pests; but all states s re the inability to If the district at the time of dissolution comprised only protect the selves fully against those p is which present unincorporated territory in two or more counties, its property serious d gers to them. vests in those counties in proportion to the assessed value of 3. a migratory character of pest infes tions makes it each county's property within the boundaries of the district necess for states both adjacent to and dis t from one as shown on the last equalized county assessment roll. anot r, to complement each other's activities hen faced If the district at the time of dissolution comprised both wi conditions of infestation and reinfestation. incorporated and unincorporated territory, its property vests 4. While every state is seriously affected by a stan- in each unit in proportion as its assessed property value lies al number of pests, and every state is susceptib of within the boundaries of the district: PROVIDED, HOWEV- (1992 Ed) [Title 17 RCW—page 431 Dr. Ned Walker's Biosynopsis of. . . TIie Eastern Treehole Mosquito Aedes . , Importance mid-summer. Aedes triseriatus has pile where they are produced. Aedes triseriatus is not the mosquito become an important urban mosquito "" - that you slap in the evening,or the one because of its association with scrap that has Joe Public on the phone all tires. ` : summer long with complaint calls. It just isn't all that abundant in most Associated Species places in its range. Aedes triseriatus In addition to the Asian tiger and never drew much attention until it was yellow fever mosquitoes,IHs larvae oc-cur with a variety of Culex and : found to be the vector of La Crosse encephalitis virus. La Crosse Anopheles mosquitoes.One mosquito, encephalitis is primarily a problem of Toxorhynchites,which preys upon'Ibis children in the upper Midwest and larvae can be a major factor regulating east.Symptoms can range from a mild the population dynamics of Tris in flu-like illness to seizures and coma. treeholes and tires. Ohio leads the nation in number of Oviposition cases, followed by Wisconsin, Min- One of the most interesting aspects ; nesota, Illinois and Indiana. Outside of Tris' biology is its diapause and this "LaCrosse encephalitis crescent," hibernation during the winter. Eggs ' a �♦' cases occur in Texas, North Carolina, ` are laid singly on the side of natural Michigan, Missouri, Iowa, West A g and man-made containers. In the Virginia and New York. north,'Ibis overwinters as eggs. Begin- Aedes triseriatus feeding on a mouse. Mus ning in mid August, eggs "sense"that musculus. Photo by: Leonard Munstermann Geographic Distribution Aedes triseriatus occurs from daylight is getting shorter. The eggs = Florida,north to Ontario and Quebec, then switch into diapause and will not Few mosquito species feed on and west to the Dakotas and Texas. hatch even if flooded. Diapause rodents. These mammals are usually From north to south, the species ex- Prevents eggs from hatching when lar- too jittery and quick to sit still for that. periences quite a range of vae will not have enough warm But Aedes triseriatus, even though it temperatures and conditions, and it weather to complete their develop- bites a wide variety of mammals, in- has successfully adapted to local ment. The eggs hatch in the spring cluding humans and sometimes birds, requirements. when temperatures rise and rains particularly likes chipmunks and draw up water levels.In the south,both squirrels. These woodland rodents are Adult DescripPoit eggs and larvae overwinter. active during the day when Aedes The tarsi and proboscis are uniform- triseriatus is seeking hosts in the ly dark. Silvery scales cover the sides = ' woods. Chipmunks and squirrels can of the thorax and are the most The amount of food available in con- become infected with LaCrosse virus diagnostic characteristic. The ab- tainers greatly influences the produc- and can infect other mosquitoes that dominal segments are dark and tion of Tris larvae. If plentiful, larvae feed on them. 'Ibis females can also unbanded. survive crowded conditions and withs- pass the virus on through the eggs to tand competition for food from other the next generation thus providing an Larval Habitat mosquitoes. In treeholes, food is overwintering mechanism for the Even though the accepted common deposited and mosquito waste pro- virus. Male Tris infected by the tran- name for"This" is the eastern treehole ducts are flushed out with rainfall that sovarial route can, in turn, infect mosquito, it also breeds in tires, main- flows over the trunk of the tree. In tires, females with the virus during mating, ly in shaded locations. It can be found the major food source is decomposing a kind of"mosquito venereal disease." in a single water-filled tire behind the leaves. garage or in a tire dump with Dr. Walker is an Assistant ht and Migration thousands of tires. In scrap tire yards, Professor of Entomology at adults reach incredibly high numbers, The flight range of adults is rather `' Michigan State University, as many as 60,000 females per acre in short and often ranges only a few hun- East Lansing. dred yards from the treehole or tire WING BEATS, SUMMER 1992 17 ENTOMOLOGY NEWSLETTER FOR CO-UNTY ' sept. 1987, No. 3, "For God so loved the entomologist that h e . . . . . Post•It"brand fax transmlltal memo 7671 w of P�aA. To rom Dept. Phone N aY O ��� axw rww D gave 4 out of every 5 creatures . . . . F, legs." 1 , i b / ), Washington State University Department of Entomology 1 - `�r -- - 31 AIDS and MOSQUITOS Lynden Baum Washington State Division of llealth Olympia, Washington r:.�n P�lrr .rlrri Lars 1-ransrni t AIDS? ;We known to tr•,insmit many different t. Pc nrd,niisms t:o t►uigans, inciudinq those that causepmalaria, plague, encephalitis, yellow fever and others, plaque• bIon(l-sucking arthropods can transmit disease: abiolo0 biologically which tw rilechall ica 1 ly. Kiotnglicdl tr.)risrnission occurs when the insect paras with a LCs parr,)site which must then multiply inside�tillesinsect. Tileected r,nl.errthen�host 'suF lrybodynWhenstiley in to insecttheg insect 's salivary and uF its feeding, secretes saliva during lthe scourse On p 9• 1t 'is probable that blood-sucking arthropods may feed peo le infected with AIDS virus and ingest infected blood. In fart, niosq�litoes have been allowed to feed through membranes on human blood thrit contained e co is 1 million times morg AIDS virus than an infected persgrn would have coursing through his body Fort r-e.searchors were able to find the virus in the mosquito hours later, Lhr: virus f,�ils to multiply or make its way4 put However, rlis•�ppg:'ars as the blood meal - digested b to the salivary glands and dcrc; nol: he(..orne infected. Therefore, transnlissiensof �tile AIDS virus t! scone, unlikely by this route, ► f You Cain Acquire the AIDS Virus From Using rr"nl t11e Contaminated Piercing Mouth Parts o a faCMosquitoted Needle, Wily Not o? This route of disease tranmission would be mechanical . The idea her i.liat a sinall amount of infected blood remains on the mosquito' proboscis p e is (Mouth arts after a bite. The insect bites a second person and the virus is passed on. Mechanical arthropod-borne virus irAnSrpission is not unknown. For example, Bovine leukemia virus a rotrovir►rs like the AIDS virus, has been shown experimentally to be rnr:chanically transmitted by horseflies. However, mechanical to' i.r,rnsmission of the AIDS virus by mosquitoes seems Impossible. rt•asryn is the volume of residual blood involved. The mouth e The m0r,gUILo do not hold enough residual blood to give an infectious dose. It has been estimated because of the low viraemic level f pal^ts of a virus In AIDS patients and the high virus numbers nePdedOf circulating i►rciividual that a mosquito would need to bite an individu to al in excess �'.oOD titres to eCt an generoliy do nott feed forreseveralldaysaord mot-e art to this that mosgUitoeS of ieeding. All of this makes mechanical transmissioncpleting a possibIIIty, n a very remote C� r 37. Whirl. !\bout. I.hQ high Prrcentage of AIDS Cases in Areas with Lots of Mosquitoes L il.r Africa and Florida? Arthropods have been hypothesized recently as a mode of t5ansmission of Lhr AIDS virus in Belle Glade, Palm Beach County, Florida . This area han one of the highest AIDS incidence in the united States and also has a frodit. ionally high mosquito population. The National Centers for Diseaso Control recently completed a study of Belle Glade residents . The studies in Belle Glade show that AiDS virus infection occurs primarily from sexual transmission among homosexuals and bisexuals, and from the use of contaminated needles by IV drug users, in the 18-49 ,year old arse group. Mosquitoes do not selectively bite 18-49 year old IV drug users , prostitutes, homosexuals, and bisexuals. Secondly, antibody presence to a number of common indigenous South Florida mosquito-borne arhoviruses was measured in community residents. - There was no significant difference among AIDS virus infected and non-infected individual , to the presence of antibodies from the five arboviruses. If [be AiDS virus were transmitted by mosquitoes, you would expect all ages to by equally infected. The vvidence against arthropod transmission of AiDS in Africa is also quii.e substantial , in those areas where AIDS is prevalent , so is malaria, We find approximately 90% of the children in some of these areas have had malaria; yet, AIDS virus infection is uncommon in children who were not born to infected mothers . The hypothesis that mosquitoes transmit the AIDS virus in the Belle Glade community, ar- olsewhore, is not supported by the AIDS surveillance data. Rpuerences i Booth, W. , "AIDS and Insects, " Science, 237 ( 1987) pp. 355.56. 2 Heniq, R.M. , "AIDS and Mosquitoes, " Washington Post, 1 July 7, p. 7. 3 "CDC Acquired Immunodeficiency SyndromeJAIUSI -Tn Western Palm Beach 4 County, Florida, " MMWR, 35 (1986) pp. 609-12. Pint, P. and Schofield, C. , "No Evidence for Arthropod Transmission of AIDS," Parasitolo Y_Toda 2 ( 1986) p �94 v p ' KILLER BEE ' DEFENSE PACT (Washington Times) -- The United States and Mexico will sign an agreement this summer to create a program that could delay by a , decade the arrival in Texas of Africanized honeybees , according to Don Husnik , associate deputy administrator for Plant Protection and Quarantine of APHIS. The agreement would set up a biological barrier at Mexico's narrowest point, the Isthmus of Tehuantepec . � -- - - - - --- -- - - - - - - -- - - -- - - -- -- -- - - - - - - - -- - -- -- - - -- - -- - - - - - - - - -- - - - - - - - - - - - - - - - - - rPGM:AG PESTICIDE r•1GMT TO:GP42919920653664G2 DEC 16. 1941 Mosquito Control Districts 17.28.259 17, 2-1 tl (9) Acquire by gift. devise, bequest, lease. or pur- Se,errblluv-- Ffre<the d41H Ond urmtnslloe 4010A .nnsrnw'- chase. real and personal property necessary or eonve- 1►on----191i 141 er.s.c 195:Set note: following MW 84.52.04). atone for its purposes. 17,28,25-1 District boundaries for tax purposes. For (10) Make contracts, employ engineers. health offi- the purpose of property taxation and the levying of cots, sanitarians, physicians, laboratory personnel, allot- property taxes (lie boundaries of the mosquito control neys, and other technical or professional assistants: and publish information or f!teraturc and do any and all district shall be the established official boundar}' of such other things accessary or incident to the powers granted- district existing on the first day of September of the year by, and to carry out the prvjccts specified in this chap- in which the levy is made, and no such levy shall be ter. (1981 c § I; t957 C 15J § 16.] made for any mosquito control district whose boundaries c r,�frr���i are not duly established on the first day of September of 17.28.17 Mosquito breeding places declared public such year. (1959 a 64 15.1 nit , rrccf�---Abatement. Any breeding place for mos- 17.28.254 Abatement, extermloolion deellsred nPce4- quitoes which exists by reason of any use made of the oily and benefit to land. It is hereby declared that when- land on which it Is found or of any artificial change in ever the public necessity or welfare has required the its natural condition is a public nuisance: Provided, That formation of a mosquito control distric(, the abatement conditions or usage of land which are beyond the control or extermination of mosquitoes within the district Is of of the landowner or are not contrary to normal, accepted direct, economic benefit to the land located within such practices of water usage in the district, shall not be con- district and is necessary for the protection of the public sidcred a public nuisance, health. safety and welfare of those residing therein. The nuisance may be abated in any action or pro- 11959 c 64 § 6.1 ceeding, or by any remedy provided by law, 11959 c 64 § 2; 1957 c 153 § 17.) 17.28.255 Classification of property As.seg+- ments. The board of trustees shall annually determine 17.28.250 interference with entry or work of dis- the amount or money necessary to carry on the opera- trict Penalty. Any person who obstructs, hinders, or tions of the district and shall classify the property interferes with the entry upon any land within the dis- therein in proportion to the benefits to be derived from trice of any officer or cmpio}ce of the district in the the operations of the district and in accordance with performance of his duty, and any person who obstructs, such classification shall apportion and assets the several interferes with, molests, or damages any work performed lots, blocks, tracts, and parcels of land or other property by the district, is guilty of a misdemeanor. 11957 c 153 § within the district. which assessment shall be collected . 25.1 with the general taxes of the county or counties. 11959 e 64 § 7.1 17.29.251 Borrowing monev or Issuing warrants In anticipation of revenue. A mosquito control district mnv, 17.28.296 Assessments Roll, hearings, notices, prior to the receipt of taxes raised by levy, borrow objections, appeal. etc. The board of trustees In assessing money or issue warrants of the district in anticipation of the property within the district and the rights, duties and revenue. and such warrants shall be redeemed from the liabilities of property owners therein shall be governed, first money available from such taxes. (1959 c 64 § 3.1 insofar as Is consistent with this chapter, by the provi- sions for county road improvement districts as set forth 11.28,252 Excess levy authorized. A mosquito con. in RCW 36.89.090 through 36,98.110, 11959 a 64 § 8.) trol district shall have the power to levy additional taxes 17.28 257 Assossments.—Pa yment, lien deHn -ten- in excess of the constitutional and/or statutory litnitu- Iles, foreclosure, etc. The provisions of RCW 36.88 120, tions for anv of the authorized purposes of such district, 36,88.140, 36,88.130. 36.88.170 and 36-88.180 govern- not in excess of fifty cents per thousand dollars of as• ing t11e liens, collection, payment of assessments, delin• :essed value per year when authorized so to do by the quent assessments, interest and penalties, lien electors of such district by a three-fifths majority of foreclosure and foreclosed property of county road im- those, noting on the proposition in the manner set forth in provenient districts shall govern such matters as applied Article VII, section 2(a) of the Constitution of this state, to mosquito control districts. (1959 a 64 19,1 as amended by Amendment 59 and as thereafter amended at such time as may be fixed by the board of 17.28.259 County treasurer---Vallee. The county trustees for the district, which special election may be Treasurer shall collect all mosquito control district as. called by the board of trusties of the district, ai which sessmenis, and the duties and responsibilities herein im• special election the proposition of authorizing such ex- posed upon him shall be among the duties and ccss Icvy shall be submitted in such form as to enable responsibilities of his office for which his bond is given the voters favoring the proposition to vote 'Yes' and tt:osc opposing thereto to vote 'No". Nothing herein is county treasurer. The collection and disposition of shall be construed to present holding the foregoing sae- revenue from such assessments and the depositary vial election at the same time as that fixed for a general thereof shall be the same as for tax revenues of sorb districts as provided 1n RCW 11.28.270. (1959 c 64 election. i1973 Ist ex.s, c 195 § 3: 1959 c 64 § 4.1 § 10.� 1j4v rd t (Title 17 RCW--p 391 SPIDERS ARE SPIDERS HARMFUL? Most spiders are beneficial.They feed on a variety of small insects including mosquitoes,moths and flies.Their intricate webs are usually built in stra- tegic locations like windows,ceilings and corners. Since the webs are highly visible,most homeowners choose to remove them.Except for a few danger- ous species,spiders should not be killed. ARE THERE ANY POISONOUS SPIDERS IN WASHINGTON? Yes. The aggressive house spider is common throughout the state and is quite common in and around homes in western Washington.It gets its name from its habit of biting with little provoca- tion when cornered or threatened. The black widow spider is common in eastern Washington. Contrary to popular belief,the brown recluse spi- der does not occur naturally in Washington. WHAT DO AGGRESSIVE HOUSE SPIDERS LOOK LIKE? These spiders are large with long hairy legs,and brown bodies about 1/2"long.They usually have whitish,parallel lines lengthwise on their backs. WHERE ARE AGGRESSIVE HOUSE SPIDERS FOUND? They are commonly found in unfinished base- ments, garages, crawl spaces or around houses where heavy shrubbery grows against the house. They often wander long distances and are swift runners.These spiders build funnel-shaped webs and can often be seen waiting for prey in the middle of the funnel. WILL SPIDER BITES HURT ANYONE? The initial bite of the aggressive house spider is like a very slight prick and is not painful.Reactions vary. In sensitive people, an insensitive hard area sur- rounded by a 2-6 inch reddened area may appear in less than 1/2 hour.The area later blisters revealing a 1/2"to 1" lesion that may take months to heal. The bite is often accompanied by a severe headache wluch lasts 2-7 days.Some victims also experience nausea,weakness,tiredness and vision impairment. Bites from these spiders rarely cause death,but the slow healing of the bite usually leaves a permanent scar. WHAT CAN I DO TO KEEP THESE SPIDERS OUT OF MY HOUSE? • Check doors and windows.Repair any holes large enough for spiders. • Check firewood for silk egg sacs and spiders before bringing inside. • Remove spiders and webs from dark corners with a vacuum cleaner.Empty bag immedi- ately after cleanup. • Don't allow heavy shrubbery to grow against the house. For those who really dislike spiders,a regular tree and shrub spraying program reduces spiders around the house.Spring and fall perimeter treatments and annual crawl space sprays can greatly reduce spider populations around the house. If you have been experiencing spider problems,call Whitworth Pest Control.We'll spray problem areas with a recommended dose of an effective insecti- cide.We'll also inspect your home to help you stop future invasions. WHITWORTH %0 PEST CONTROL 3707 96th St.E. Tacoma,Washington 98446 Terry Whitworth,Ph.D. 535-1818 Entomologist Aquatic Mosquito Insecticides Water Quality Program Manager Approval September 1991 GUIDELINES TITLE: Policy for Issuing Short-term Modifications to State Surface Water Standards for the Application of Mosquito Control Insecticides PURPOSE: This policy delineates the process and the regulations involved with obtaining a permit to apply insecticides for the purpose of mosquito control to the surface waters of Washington State. The application of any polluting substance - including insecticides - to the surface waters of the State requires a short-term modification permit (STM) from the Department of Ecology (Ecology) . Ecology is authorized to require STMs for the application of aquatic insecticides by Chapter 90.48 RCW, the State of Washington Water Pollution Control Act and Chapter 173-201 WAC, the State Surface Water Quality Standards. Ecology's Water Quality Program is responsible for establishing the STM permit process; for issuing or denying permits following an application review; for compliance monitoring and enforcement; and for developing and implementing public information and education activities regarding permit requirements. Ecology recognizes that mosquito control districts and local and state health jurisdictions have responsibility for protecting human health through mosquito abatement. This policy includes measures to incorporate the expertise of mosquito control professionals and health officials in making determinations concerning the proper aquatic treatments for mosquito control in situations where mosquitos represent a public health risk. SCOPE OF THIS POLICY There are three principal methods for the control of mosquitos. In order of preference they are 1) source reduction through habitat modification, 2) larva and pupa control, and 3) adult control. The principal concern of this policy is with the method of larva and pupa control. The larval and pupal stages of the mosquito' s life cycle take place in an aquatic environment, and treating for mosquitos in this stage involves the use of aquatic insecticides or biological control methods. The time period for accomplishing source reduction is before the mosquito season begins, when measures can be taken to prevent mosquito outbreaks. Whenever possible, steps should be taken to prevent mosquito outbreaks by removing the aquatic habitat they require to reproduce. Removing tire piles, turning empty barrels upside down, making sure that construction sites do not have areas which will support standing water - these are examples of source reduction through habitat modification which can help in preventing the emergence of mosquitos. From an environmental perspective, source reduction is the preferred method for controlling mosquitos since it does not involve the application of any foreign substances to the State's waters. However, reduction of standing water to control mosquitos must be consistent with the State's wetland policies and the Hydraulic Act, Chapter 75.20.100 RCW, administered by the Department of Wildlife or Fisheries. Adult control, which occurs after the mosquitos have hatched and are "on the wing, " requires the use of upland treatments. Upland treatments for adult control do not involve the application of aquatic insecticides and are therefore not addressed in this policy. Inquiries concerning upland treatments should be addressed to the Washington State Department of Agriculture. ROLES AND RESPONSIBILITIES Ecology's regional offices have the responsibility for issuing STMs for the application of aquatic insecticides for mosquito control. The permits are valid for no more than one year. Headquarters will provide guidance to the regional offices to insure consistency in policy development and implementation. Mosquito control districts, health departments, applicators, and any other entities involved in mosquito control programs are responsible for applying for a permit, and for abiding by the guidelines and regulations stated in this policy as well as applicable Administrative Orders. Ecology' s regional offices will target a turnaround time of 30 days on STM requests, unless the application plan requires an external review to meet SEPA requirements (see below) . If the application plan requires external review, Ecology's regional offices will target a turnaround time of no more than 45 days. EVALUATION OF SHORT-TERM MODIFICATION REQUESTS At the beginning of the mosquito control season the applicant will apply to the appropriate regional office for a STM. At a minimum, the applicant must submit a treatment plan (hereafter known as the "application plan") for the entire season's activities. The application plan should detail anticipated areas of treatment and the 2 treatments to be used in specific locations. In cases where it is impossible to anticipate just when and where treatments will occur, the regional office shall only approve the most conservative treatment plan, as defined by the order of uses laid out in this policy. Whenever possible, a map of the region where the treatments will occur, with the treatment areas highlighted, is desirable. Compliance with the State Environmental Policy Act (SEPA) is required before a STM can be issued. SEPA requires that the applicant complete a SEPA checklist, which will be used by the lead agency to determine if the proposal will have possible significant adverse environmental impacts. When necessary, Ecology's regional office staff will assist in determining which agency is the lead agency. If no significant adverse impacts are likely, a Determination of Non-significance (DNS) will be issued, with a 15-day period for public comment. The DNS will be submitted to Ecology with the application plan. If significant adverse impacts are likely, a Determination of Significance (DS) will be issued. A DS will necessitate either the adoption of an existing Environmental Impact Statement (EIS) , in which case the DS will require a 7-day review period, or completion of a new EIS. The DS must also be submitted with the application plan. In those instances where the application plan remains the same from one year to the next, and where SEPA requirements have previously been met, the lead agency may choose to adopt an existing DNS or DS. In such cases, the applicant need not complete a new SEPA checklist. If the application plan is approved, the regional office will issue a STM for the waterbodies covered in the plan. Unless the STM has expired or the approved application plan changes, applicators will not need to obtain a STM each time they treat individual waterbodies within the area covered by their application plan - the STM will be a general permit to treat a variety of waterbodies (i.e. those detailed in the application plan) for the time period specified in the permit. The STM will be valid for the time period specified by the regional office, but the time period shall not exceed one year from the date it is issued. Approval of requests for STMs by the regional offices will be granted to those applicants who demonstrate in their application plans that due consideration has been given to those treatments which are considered to have the least environmental impact (see below) . For the purposes of this policy, "due consideration" means that the applicant has considered and either 1) plans to use the least impacting treatment, 2) can demonstrate in the application plan why this is either not possible or would prove to be ineffective, or 3) can demonstrate that the proposed treatment site contains a mosquito population which constitutes a public health threat. Application plans should give due consideration to the following treatments in the following order: 1. Habitat Modification 2. Biological Controls 3 . Chemical Controls Biological and Chemical Controls Insecticides with Bacillus thuringiensis israelensis (Bti) or methoprene in liquid form' as the active ingredient will be the only insecticides allowed for mosquito control in waters of the state unless: ' Technically, methoprene is considered by the EPA to be a "biochemical. " 3 1) The mosquito problem is such that there is a public health risk. 2) Bti and methoprene liquid are known to be ineffective at a specific treatment site. 3) The waterbody is non fish-bearing. Methoprene in pellet and briquet form may be used only in isolated, non fish-bearing waters. Chemical insecticides should be used only after habitat modification and biological control treatments have been given due consideration. Proposed chemical insecticide treatments in the application plan will be considered by the appropriate regional office on a case-by-case basis. Following is the approved list of biological controls in the order in which they should be considered in the application plan: Agent Common Trade Names Bacillus thuringiensis israelensis (Bti) Acrobe Bactimos Vectobac Teknar Methoprene Liquid Altosid Mosquito Fish (Gambusia affinis) N/A Three-spined Stickleback - N/A (Gasterosterous aculeatus)2 Methoprene Pellet or Briquet Altosid Following is the approved list of chemical insecticides' in the order in which they should be considered in the application plan: Chemical Name Chemical Family Common Trade Names Monomolecular- Nonionic Arosurf MSF Surface Film Surfactant Petroleum Petrochemical Golden Bear Oil Distillate Pyrethrum Pyrethrins Pyrenone' Methoxychlor Chlorinated Methoxychlor 2EC Hydrocarbon Malathion Organophosphate Malathion 5 Malathion 8 Spray Malathion 8EC Malathion 55 2 Introductions of both the Mosquito Fish and the Three-spined Stickleback must be approved by the Washington State Department of Wildlife. See Appendix. 3 Please check with the Washington State Department of Agriculture to confirm whether a product is registered for aquatic use. ' Pyrenone may be used in non-fishbearing waters only. 4 Temephos Organophosphate Abate - 1-SG (1%) 2-SG (2%) 5-CG (5%) 4-E (44%) Fenthion Organophosphate Baytex BX 2 Coated Granules Chlorpyrifos Organophosphate I Dursban 2 PROCEDURE FOR EVALUATING NEW AQUATIC INSECTICIDES The above list represents the most widely used mosquito control products. However, Ecology is aware that new products appear frequently. Applicators who wish to obtain a STM for an insecticide which is not contained in this policy must propose the inclusion of the new insecticide to the appropriate regional office. If the proposed insecticide is simply a new trade name for an already approved chemical, such as malathion, then the regional office shall approve the request without consultation from headquarters. The regional office will then forward the name of the new insecticide to headquarters for inclusion in this policy. However, if the request for a new insecticide involves the inclusion of a new biological agent or chemical which is not on this list (either a new chemical name or a new chemical family) , then the regional office will forward this request to Ecology headquarters in Olympia. The request will be considered by a panel comprised of a representative from each of the following parties: Department of Agriculture Department of Ecology Department of Health Department of Wildlife Northwest Mosquito Control & Vector Association Upon receiving a request, the panel will consult with mosquito control applicators, manufacturers and other recognized experts, to determine whether the proposed biological agent or chemical should be included in this policy and will make a recommendation to Ecology in accordance with that determination. The panel will also recommend where the treatment should be placed in the order of considerations. CONTROLS ON INSECTICIDE APPLICATION * Notification of the appropriate Department of. Ecology regional office shall not be required immediately prior to each treatment as long as dates and treatments for the mosquito control program have not changed. * The results of monitoring plans, when they exist, shall be available to Ecology upon request. If a monitoring plan is not available as a basis for making application decisions, Ecology will work with applicators and the Department of Health to establish an application specific to the area to be treated. * All application of mosquito control insecticides to wetland ecosystems shall be consistent with Ecology's wetland protection policies. * The applicant must comply with all SEPA requirements. * Public notification will be required at least 24 hours, but not more 5 than 10 days, prior to the commencement of :initial mosquito control activities. After the season begins, continuing notification is required on approximately a monthly basis until mosquito control activities are completed. Notification can include information in newspapers, posting of property, radio/television public service announcements, handbills, mailings to adjacent landowners, or all of the above notification procedures. When specified on the permit, notification shall be given in English and Spanish. Notification shall include the name of the material (s) used, where it is to be applied, any restrictions needed to protect human health and livestock, and the name and phone number of the applicator and of Ecology's regional office. * Notification shall be posted at all reasonable points of ingress and egress to the treatment area when insecticides with water-use restrictions are applied to waterbodies which are used for water supply (i.e. domestic, industrial, agricultural) , stock watering, fish and shellfish harvesting, and water contact recreation (i.e. swimming, boating, etc. ) . APPENDIX MOSQUITO CONTROL INSECTICIDES SUMMARY Bacillus thuringiensis israelensis (Bti) : Bti is an endospore-forming bacterium that is ingested by the actively feeding larvae. An endotoxic protein produced by the bacteria converts into a toxic substance after ingestion to cause paralysis and death of the target insect. Bti is highly selective for the first and second instar of mosquito, and some gnat larvae. Bti is the primary material used for mosquito control because of its low toxicity to non-target species, with the exception of certain species of Diptera and Lepidoptera. Bti is not effective against certain species of mosquito, and therefore may have to be used in conjunction with other treatments. Timing of treatment is important and Bti must be applied frequently. Mosquito Fish: The Mosquito Fish, Gambusia affinis, has been used for mosquito control in virtually every state because of the adult' s ability to consume large numbers of mosquito larvae. These small, warm water fish rarely exceed 2.5 inches, and prefer shallow water. They tend to flourish in almost any environment including well discharges, cisterns, water tanks, potholes, rain barrels and open septic tanks. Gambusia have been known to dramatically reduce and even eliminate mosquito larvae. Washington Department of Wildlife suggests that the use of Gambusia be integrated into an overall mosquito control plan rather than be used as an exclusive solution to mosquito abatement. Approval must be obtained from the Washington Department of Wildlife for use of this species as a mosquito control measure. Three-shined Stickleback: The Three-spined Stickleback, Gasterosterous aculeatus, is known to be an effective predator of mosquitos. The Three- spined Stickleback is native to Washington State; however, any introduction of this fish into waters where it is not already established must be in accordance with the Department of wildlife's Exotic Fish policy. Methoprene in granules, briquets, and liquid: Methoprene is a growth regulator which is effective on the second, third and fourth instar stages. Since methoprene has no effect on pupae or adults, it must be applied during the larval stage. Methoprene in briquet and pellet form is considered toxic to fish, wildlife and bees, and therefore may only be used in isolated, non-fish bearing waters. Methoprene in liquid form may 6 be applied to fish-bearing waters. Monomolecular Surface Film (MSF) : MSF is a non-petroleum surface oil that acts as a physicochemical agent by altering the mosquito's breeding habitat. It belongs to the alcohol ethoxylate group of surfactants, which are used in detergent products. MSF disrupts the cohesive properties which allow mosquitos to use the water's surface as an interface for breeding. By making the surface "wetter, " MSF in effect drowns mosquitos. MSF kills larvae and pupae by making it impossible for them to keep their breathing tubes above the water's surface. It also kills adult females by entrapping and drowning them when they contact the surface to lay their eggs. Since MSF kills mosquitos with a physical mechanism (rather than a toxic mechanism) , it is not expected to induce resistance in mosquitos. MSF is not effective in habitats with persistent unidirectional winds of greater than 10 miles per hour, or in areas with very choppy water. Persistence of MSF is anywhere from 2 to 10 days. Toxicology studies on mammals, birds and fish indicate that MSF has very low levels of toxicity. Golden Bear Oil : Golden Bear Oil is a highly refined diesel oil that effectively kills mosquito pupae. Golden Bear forms a thin sheet of oil on the surface water and persists for 12 to 15 hours. It suffocates many aquatic insects by interfering with the insects' breathing tubes. Apparently, Golden Bear does not affect fish directly because the oil remains on the water's surface for only a short period of time, then evaporates. It may affect fish indirectly by depleting their food source. Aquatic invertebrates, amphibians, waterfowl and furbearers may be deleteriously affected. Consequently, to determine whether any species of concern (endangered, threatened, economically valuable) inhabit the area to be treated, coordination with the Department of Wildlife and Department of Natural Resources' Natural Heritage Program is required before Golden Bear oil may be used. Pyrethrins: Pyrethrins are the active insecticidal constituents of pyrethrum flowers (Chrysanthemum) . Pyrenone is non-toxic to mammals, but is toxic to fish, shrimp, crabs and other organisms. Pyrenone should only be used in isolated, non-fishbearing waters. Methoxychlor: This is a larval and adult insecticide. EPA laboratory data reveal high toxicity to fish and aquatic invertebrates. Research suggests Methoxychlor is practically non-toxic to birds and bees, although EPA's label information states it is toxic to bees. Organophosphates: Organophosphates encompass a major class of synthetic organic insecticides. These compounds kill a wide range of insects, interfering with the nervous system by inhibiting cholinesterase activity. Some organophosphates kill insects on contact while others must be ingested to be effective. Organophosphates are also toxic to aquatic invertebrates, bees, amphibians, birds, fish, and mammals. Many organophosphates are water soluble and therefore do not tend to bioaccumulate or biomagnify in the food chain. Organophosphates are the insecticides most likely to have detrimental effects on non-target species, including fish, wildlife and humans. Use is limited to areas where mosquitos cannot be controlled in any other manner. Aquatic organophosphates may be applied only as approved by the appropriate Department of Ecology regional office. Before approving or denying a request to use aquatic organophosphates, regional office staff should consult with the appropriate Department of Health office for assistance in determining whether public health considerations warrant their use. 7 t\Journal of the American Mosquito Control Association, 10(2):202-210, 1994 Copyright m 1994 by the American Mosquito Control Association,Inc. METHOPRENE CONCENTRATIONS IN FRESHWATER MICROCOSMS TREATED WITH SUSTAINED-RELEASE ALTOSID O FORMULATIONS DOUGLAS H. ROSS,' DAN JUDY,'BRIAN JACOBSON2 AND ROBERT HOWELL2 ABSTRACT. Five sustained-release methoprene formulations were applied to microcosm tanks at maximum label rates to measure methoprene concentrations in the water over time. Replicate water samples(i liter each; 4 samples/microcosm/date; n = 432)were collected pretreatment and 1, 2, 4, 7, 14, 21, 28,and 35 days posttreatment,and analyzed for methoprene residues using capillary gas chro- matography. The highest(S)-methoprene residue detected in any individual sample on any date was 6 µg/liter.Eight-five percent of all samples contained residues<_1.0 µg/liter;71%were below the minimum quantitation limit(MQL=0.2 µg/liter).Neither ALTOSID® Briquets,XR Briquets, Pellets,nor exper- imental granules produced (S)-methoprene concentrations >_10 µg/liter, the Expected Environmental , Concentration produced by application of ALTOSID Liquid Larvicide at 4 fluid oz./acre(293 ml/ha). These data indicated that use of these solid,sustained-release methoprene formulations does not constitute any undue risk to nontarget organisms,compared to the use of ALTOSID Liquid Larvicide. INTRODUCTION• on the methoprene levels produced by the solid The insect growth regulator(IGR)methoprene formulations have been developed(Knuth 1989). was first registered by the U.S. Environmental If the A.L.L.formulation(5/o(S)-methoprene; Protection Agency (EPA) for mosquito control 0.43 lb/gallon [51 g/liter])is applied at the max- in 1975(Anonymous 1975).In the ensuing years, tmum label rate (4 fluid ounces/acre [293 ml/ its activity as a mosquito larvicide has been clearly ha]) to water 6 in. (15 cm) deep, the Expected shown(Dame et al. 1976; Rathburn et al. 1979; Environmental Concentration (EEC) of(S)- methoprene is 10 µg/liter.The concerns alluded Sjogren et al. 1986;KraFlomer et Beesley 19 1)' to above stem from the unassessed potential for Logan et al. 1990; Kramer and Beesley 1991). the solid formulations to produce methoprene Over this same time,numerous studies have also levels above the 10 jig/liter EEC for A.L.L. Due demonstrated this IGR's favorable toxicological to this data gap,the United States Environmental profile(Wright 1976,Garg and Donahue 1989),its minimal impact on nontarget organisms protection Agency(EPA)has required that labels (Miura and Takahashi 1973,Quistad et al. 1976, for these solid products carry the following pre- Schooley and Quistad 1979, Batzer and Sjogren cautionary statement: Do not apply to known 1986), and its short environmental persistence fish habitat(s)". Methoprene toxicity to fish is (Schaeffer and Dupras 1973;Quistad et al. 1974, very low (Quistad et al. 1976, McKague and 1975;Schooley et al. 1975a, 1975b;Siddall 1976). Pridmore 1978, Ellgaard et al. 1979, Tietze et Despite this large, ever-growing body of sci- al. 1992);however, the EPA maintains that, in entific evidence,concerns persist about potential the absence of data to the contrary, these solid negative impacts associated with methoprene use formulations could produce methoprene levels in aquatic ecosystems for mosquito control.Re- in excess of 10 µg/liter, and that such undeter- mined "high" levels could have detrimental ef- fects on nontarget invertebrates that are an im- cently, concerns have focused on the potential environmental impact(s)of the solid,sustained- peas of source nontarget fish food. release methoprene formulations, namely AL- portBased on the observed activity of these solid TOSID® Briquets, XR Briquets, and Pellets. formulations against mosquitoes, we hypothe- The majority of aquatic nontarget and envi- sized that at maximum label rates, ALTOSID ronmental data which exist for methoprene was Briquets, XR Briquets, and Pellets do not pro- generated by studies using ALTOSID SR-10 duce aquatic methoprene concentrations in ex- (which has been replaced in recent years by AL- cess of the 10 jig/liter EEC of the A.L.L.product. TOSID Liquid Larvicide or A.L.L.),a liquid for- To test this hypothesis we designed an experi- mulation with limited residual activity and per- ment to measure the methoprene concentrations sistence in the water. To date, little, if any data present over time in aquatic microcosms treated with sustained-release ALTOSID formulations 'Technology Development, Zoecon Corporation, under field conditions. 12200 Denton Drive, Dallas, TX 75234. Present ad- dress:Farnam Cos.,Inc.,301 W.Osborn,Suite 2000, Phoenix,AZ 85013. 2 Analytical Biochemistry Laboratories, 7200 East 'Personal communication, Environmental Eflects ABC Lane,Columbia,MO 65202. Branch,EPA, 1990. 202 r JUNE 1994 MOSQUITO LARVAE IN BED OF MEKONO RIVER 201 ponent, AFRIMS, for support, encouragement, ations(Diptera:Culicidae).Contrib.Am. Entomol. and reviewing the manuscript and to Daniel Inst.(Ann Arbor) 17(4):1-195. Strickman and Ronald Ward,Department of En- Harrison,B.A.,R. Rattanarithikul,E. L. Peyton and K.Mongkolpanya. 1991. Taxonomic changes,re- vised occurrence records and notes on the Culicidae search,for their helpful comments and reviewing of Thailand and neighboring countries.Mosq.Syst. the manuscript.Special acknowledgement is ex- (1990)22:196-227. pressed to Cmdr.Somboon Somabha R.N.,Chief, Ho, C., T. C. Chou, T. H. Ch'en and A. T. Hsuch. River Works and Transport, Secretariat of the 1962. The Anopheles hyrcanus group and its rela- Mekong Committee, for his helpful suggestions tion to malaria in East China.China Med.J.81:71- and loan of Mekong maps.Special thanks to Suda 78. u aishi,M.S.,M.Ahmed and G.Gramiccia. 195 . partment of Entomology, AFRIMS, for labora- 1 Ratanawong and Prasertsri Rohitaratana, De- Q pre-monsoon malaria transmission in the district Mymensingh, East Pakistan. Bull. W.N.O. trio o tory assistance, Prachong Panthusiri for prepay- 682 ing the figure,and Somprathana Kiewlongya for Ramachandra Rao,T. 1984. The anophelines of In- typing the manuscript. dia, revised ed. Malaria Research Center, Indian Council of Medical Research, Delhi. Rattanarithikul, R. 1982. A guide to the genera of REFERENCES CITED mosquitoes (Diptera: Culicidae) of Thailand with Benjaphong,N.and R.Rattanarithikul. 1991. Zeug- illustrated keys, biological notes and preservation nomyia gracilis Leicester(Diptera:Culicidae),anew and mounting techniques.Mosq.Syst. 14:139-208. genus and species occurrence record from Thailand. Rattanarithikul,R. and C. A.Green. 1986. Formal Mosq.Syst.23:53. recognition of the species of the A nopheles maculat us Division of Epidemiology. 1993. Preliminary annual group(Diptera:Culicidae)occurring in Thailand,in- summary. Division of Epidemiology, Ministry of cluding the descriptions of two new species and a Public Health,Thailand. preliminary key to females.Mosq:Syst.18:246-278. Green,C.A.,R. F.Gass,L. E.,Munstermann and V. Reid,J.A. 1968. Anopheline mosquitoes of Malaya Baimai. 1990. Population genetic evidence for two and Borneo.Stud.Inst.Med.Res.Malaya 31:1-520. species in Anopheles minimus in Thailand.Med.Vet. Reinert, J. F. 1990. Medical entomology studies- Entomol.4:25-34. XVII. Biosystematics of Kenknightia, a new subge- Green,C.A.,R.Rattanarithikul,S. Pongparit,P.Sa- nus of the mosquito genus Aedes Meigen from the wadwongporn and V. Baimai. 1991. A newly-rec- Oriental Region(Diptera:Culicidae).Contrib.Am. ognized vector of human malaria parasites in the Entomol.Inst.(Ann Arbor)26(2):1-1 19. Oriental Region,Anopheles(Cellia)pseudowillmori Subbarao, S. K. 1988. The Anopheles culicifacies (Theobald, 1910).Trans. R. Soc. Trop. Med.Hyg. Complex and control of malaria. Parasitol. Today 85:35-36. 4:72-75. Gould,D.J.,R.Edelman,R.A.Grossman,A.Nisalak Thurman,E.H.B. 1959. A contribution Ina revision and M. F. Sullivan. 1974. Study of Japanese en- of the Culicidae of northern Thailand. Univ. Md. cephalitis virus in Chiangmai Valley,Thailand.IV. Agric.Exp.Stn.Bull.A-100:1-177. Vector studies.Am.J.Epidemiol. 100:49-56. Zhang,S.Q.,Q.J. Zhang, F.Cheng, L. L. Wang and Harrison,B.A. 1980. Medical entomology studies- G.P.Pen. 1991. Threshold of transmission of Bru- XIII.The Myzomyia Series of Anopheles(Cellia)in gia malayi by Anopheles sinen.sis.J.Trop.Med.Hyg. Thailand,with emphasis on intra-interspecific vari- 94:245-250. JuNE 1994 METHOPRENE CONCENTRATIONS IN FRESHWATER MICROCOSMS 203 MATERIALS AND METHODS natural precipitation offset any evaporation losses. Study site: The study was conducted at the A Unidata(Mode16003B)data logger was set University of Mississippi Biological Field Sta- up on-site to record daily air and water temper- tion in Lafayette County,near Oxford,in north- ature.Water temperatures were also checked us- central Mississippi near the southeastern corner ing thermometers installed in 6 of the tanks(tank of the Holly Springs National Forest. The 710- numbers 7-12).Rulers were installed in each tank acre(287-ha)station contains more than 140 reg- to monitor changes in water levels. Two rain ulated research ponds and wetlands ranging from gauges were installed on-site to monitor rainfall. 0.1 to 1.5 acres(0.05-0.6 ha).Numerous springs Climatological data that were collected by hand provide exceptionally high quality water to all were gathered on a daily basis for the first week ponds year-round. The station has a full time and then 3 times a week including the sampling manager and staff, a fish hatchery building, ar- day for the duration of the study. tificial streams and a wide diversity of aquatic Test material application: A single applica- and terrestrial habitats. The microcosms were tion of each test substance (at maximum label constructed specifically for this study. rate) was made to the microcosms on October Plot preparation and maintenance: The mi- 15, 1991. Each formulation was applied to 2 crocosm area was prepared on September 2, 1991. tanks,and 2 additional tanks served as untreated The site area measured approximately 87 ft.(27 controls. ALTOSID Liquid Larvicide (A.L.L.; m)long x 34 ft.(10.4 m)wide:The slope of the 5% (S)-methoprene) was applied at 4 fluid oz./ 'test site was level. Tanks and liners were set up acre(293 ml/ha; 310 µl/microcosm). ALTOSID on September 3 and 4.The test system consisted Briquets(7.9%(R,S)-methoprene) and XR Bri- of 12 tanks arranged in 2 parallel rows(6 tanks/ quets(1.8%(S)-methoprene)were applied at the row). Each microcosm consisted of a 12 ft. (3.7 rate of 1 briquet/microcosm(= 1 briquet/1 13 ft.2 m)-diam x 4 ft. (1.2 m)-deep steel tank with 21 [10.5 m2]). (The maximum label rate for both polyvinyl chloride plastic liner placed inside. Briquets is 1/100 ft.2[9.2 m2];however,because Plastic liners were 12 ft. (1.2 m) diam and 5 ft. Briquets are not readily divisible, only one was (1.5 m)in height, which allowed for a 4 ft. (1.2 used in these 12-ft. tanks, which have a surface m)tank height plus overlap.The tanks were lev- area of 113 ft.2.)ALTOSID Pellets(4%(S)-meth- eled and had 12-14 in.(30-35 cm)of sandy soil oprene) were applied at 10 lb/acre (11.2 kg/ha; mounded up around the tank base to buffer the 11.77 g/microcosm). The experimental ALTO- water inside against temperature extremes. The, SID sand granules(SAN 81011.3 GR; 1.3%(S)- microcosm tanks and liners were new and had methoprene)were applied at 20 lb/acre(22.4 kg/ no prior history of pesticide usage. ha,22.42 g/microcosm).Prior to the application, On September 15, 1991, each tank received each tank receiving a treatment was divided into 5-6 in. (12.7-15 cm) of sediment-sandy loam 4 quadrants by 2 intersecting string lines stretched soil obtained from the station nearby. The bulk across the top of the tanks. density of the sediment was 1.46 g/cc, cation The A.L.L. was diluted in 0.5 liters of water exchange capacity was 5.6 meq/100 g, pH was and applied with a hand-held plastic squeeze bot- 5.2, moisture at I/3 bar was 10.7%, and organic tle. Approximately I/4 of the total volume of the matter was 0.3%.After the addition of sediment, bottle was delivered into each quadrant of the each tank was filled with water to a depth of 6 tank to ensure even dispersal. The bottle was in.(15 cm)above the sediment surface.The wa- then triple rinsed into the microcosm tank when ter was obtained from an unused mesocosm pond the application was finished. Both types of Bri- that was filled from a spring-fed creek that is used quets were placed into the center of the micro- as the water source for all the mesocosm ponds cosm tanks with a water sampling pole(see be- at the station (pH 6.03, hardness 20 mg/liter low). The center of the tank was determined by CaCO,, alkalinity 20 mg/liter CaCO,, conduc- the 2 intersecting string lines prior to the Briquet tivity 297 µS). placement. Due to a problem with water quality,the tanks The Pellets and sand granules were applied were emptied of water and sediment on Septem- using a separate hand-cranked spreader for each ber 25, 1991. New sediment was placed in the formulation. The total volume of each formu- tanks,and water was added to the 6 in. (15 cm) lation was divided into approximately 4 equal level on October 1-3, 1991. Additional water parts that were delivered into each quadrant of was added to the 6.25 in. (16 cm) level on Oc- the tank. tober 4 and 11, 1991. Due to natural precipita- Sampling procedures: Water samples were tion,the water depth in all tanks was 7 in.(17.8 collected immediately prior to the test substance cm)on the application day (October 15, 1991). application (day 0)and then on days 1, 2, 4, 7, No water was added after application, because 14,21,28,and 35 postapplication.On each Sam- 204 JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION VOL. 10,No. 2 pling date,4 water samples were taken from each mesh)water obtained from the same source used of the 12 tanks for a total of 48 water samples to fill the microcosms. per date(total n = 432). On each date 3 of the 6 bottles were spiked A sample (1,000 ml) comprised 10-12 indi- with 1 ml of an (S)-methoprene/dichlorometh- vidual subsamples taken at equal intervals along ane solution to a target level of 5 µg/liter. The a transect bisecting the microcosm.Each transect remaining 3 bottles were designated as control sample was taken from a different position lo- spikes.Field extraction,packaging,and shipping cated around the perimeter of the tank.The sub- of the field quality control samples were the same samples were taken with a 100-ml glass beaker as for authentic field samples. attached to the end of a wooden pole with a Laboratory analysis of water samples: Two of laboratory clamp. A separate beaker was used the 4 samples collected from each microcosm on for water collection from each microcosm, and each day were analyzed for methoprene residues. the untreated microcosms were sampled using a The remaining 2 samples from each microcosm different pole.The sampling pole was triple rinsed were held in cool storage for possible backup. with clean water between treatments as sampling Samplcool(approximatelyesanalyzed a or met storene age age wereat h ld in progressed among the treated tanks. Each sub- sample was poured directly into a 1,000-ml grad- _ oratories. Sample storage times were generally uated cylinder.(A different,,labeled cylinder was less than 2 wk from the time of sampling to the used for each microcosm.)The cylinder was filled time of extraction at the analytical laboratory. Control samples fortified at 0.2- and 200-ppb exactly to the 1,000-m1 mark.If more water was levels were analyzed concurrently with authentic needed it was added, or if excess was present it samples from day 0 through day 2.Control sam- was poured off. Because beakers did not always saes fortified at 0 t oug and 20 Control levels fill exactly to the 100-ml level,10-12 subsamples were analyzed concurrently with authenticvets were needed. The composite 1,000-m1 sample sam- ples from the remaining sample times. was poured through a 37-mesh nylon screen into Zoecon Corporation's proprietary methodol- a labeled, dated, 1,250-ml brown borosilicate ogy (Chemical Analytical Procedure #323) for glass bottle containing 75 ml of dichlorometh- analysis of methoprene in water was used to an- ane.The bottle was capped with a lid containing alyze field water samples. A Hewlett-Packard a Teflon liner and shaken for 3 min,venting the 5890 equipped with a Flame Ionization Detector bottle at 1-min intervals to avoid pressure build- (FID) was used for the chromatography of the up.Each bottle was wrapped in cellulose packing water samples. General GC parameters were as material, then placed in a black plastic bag and follows: placed in a cooler with ice.All the sample bottles Column: 30 In x 0.25 min i.d.capillary column for one sampling date were packaged on the same with 0.25-µm film thickness Supelco day.Samples were kept cool during shipment but SPB-608 fused silica(ID#119706B) not frozen. All water samples were shipped on the collec- Injector: Operate in splitless mode" tion day except for the day 0 samples,which were Purge on: 2.0 min shipped the next day, and the day 4 samples, Purge off: 59.5 min which were collected on a Saturday and shipped Detector: FID on the following Monday. These samples were Temperatures kept cool with ice during the time preceding ship- Injector: 250°C ment. All samples were shipped overnight by Detector: 300°C Federal Express, except for day 7 and day 35, Column: Initial: 80°C which were transported by personnel from An- Initial time(min): 2 alytical Biochemistry (ABC) Laboratories di- Rate: 4°C/min° rectly to the analytical laboratory. Final: 250°C Quality control: Two water samples(labora- Final time: 15 min tory QC samples, 1,250 ml each)were collected Gas flow rates on October 14, 1991,from each microcosm tank He(carrier): 1.4 ml/min and shipped to the laboratory on October 15, H2: 30.0 ml/min 1991, to be used as control samples that were NZ(makeup gas): 34.0 ml/min spiked and analyzed concurrently with the au- Air: 375 ml/min thentic samples. Head pressure: 15 PSI Field quality control samples were prepared Injection volume: 1.0 µl. on days 1, 14, and 35. Each set of samples was prepared using 6 1,250-ml brown borosilicate This GC condition change was necessary for better glass bottles filled with 1,000 ml of filtered(37- separations. 1 JuNE 1994 METHOPRENE CONCENTRATIONS IN FRESHWATER MICROCOSMS 205 The chromatographic data for the study were _ Adj.µg/liter methoprene found x 100. acquired, analyzed, and reported on the Com- Methoprene fortification puter Automated Laboratory System (CALSO). level(ppb) Peak response measurements, standard curve generation, data analysis, chromatograms, and Residues found in the water samples were cor- results reporting were performed by CALS soft- rected for percent recovery of the surrogate so- ware.The peak response for methoprene(known lution by the following calculation: and unknown)was measured and written into a calibration file containing the concentration val- Adjusted µg/liter methoprene found ues for each standard. The computer generated µg/liter methoprene found a standard curve using linear regression for meth- oprene of µg/ml detected versus peak height.The %recovery MPM µg/ml for each unknown was calculated from the 100 standard curve. The µg/liter found were calcu- Statistical analyses: The study design con- , lated from the µg/ml detected using the standard sisted of 12 microcosm tanks arranged in 2 rep- relative retention factor(STD RRF)and sample licated blocks. Treatments were randomly as- relative retention time (SMP RRT) from the signed to tanks within each replicate.This stud schedule file. The peak response for MPMs, the• g p y surrogate standard,was compared on a point-to- involved repeated measurements over time in a point basis with the average of its bracketing modification of 2-way factorial analysis ofvari- ance model known as a split-plot design (Gill • standards (preceding standard and postinjected 1978). Main plots were the sampling times and standard)to give a µg/ml calculated value. the split plots were the various chemical treat- Methoprene residue concentration was deter- ments. Data were subjected to analysis of vari- mined in CALS using the following equations: ance(ANOVA)using the General Linear Models µgem methoprene found procedure of the Statistical Analysis System.6 Means were compared using Tukey's HSD test. Methoprene peak height _ — Intercept of the standard curve Slope of the standard curve RESULTS µg/liter gross residue found Analytical method: ABC Laboratories(Study µg/ml methoprene concentration found #39409) validated the method under full EPA x Final volume(ml) x Dilution factor Good Laboratory Practices(GLPs) before initi- ation of sample analysis. Single control samples Initial volume(liter) spiked at the 0.200, 0.460, and 200 ppb levels Recovery determination was based on the sur- Were analyzed for method validation.Overall av- rogate standard MPM: erage methoprene recovery from spiked samples was 88.9 ± 8.9% (SD). Overall average MPM %recovery MPM (surrogate standard) recovery was 93.2 ± 7.3%. MPM peak height in the sample A standard curve using equiweighted least- Avg. x 100. squares fit determination for linearity for meth- MPM peak height in standards oprene was evaluated with each analytical set before and after the sample injected upon the gas chromatograph. The cor- Recoveries from fortified samples were deter- relation coefficient for these linearity curves was mined by the following formula: 0.998 or better each time. The retention times /o u for the compounds (S)-methoprene and MPM recovery methoprene remained very stable for each analytical set dur- µg/liter methoprene found ing the entire study, with average range differ- methoprene fortification level(ppb) x 100. ences of0.054 and 0.052 min,respectively.Limit of detection for(S)-methoprene was 0.1 µg/liter Recoveries from fortified samples were ad- (ppb),the lowest level on the standard linearity justed by the following formula: curve.The minimum reliable quantitation limit Adjusted%recovery methoprene (MQL) is 0.2 µg/liter (ppb), the lowest level at which acceptable recoveries were achieved. S Methylpropylmethoprene;(E,E)-l,methylpropyl 1I- methoxy-3,7,I 1-trimethyl-2,4-dodeca-2,4-dienoate; h SAS Institute,Inc.,Cary,NC 27512.U.S.Software added after laboratory extraction of field samples. release 6.04 licensed to ABC Laboratories. 5 206 JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION VOL. 10,NO. 2 Control samples: Recoveries from fortified Throughout the remainder of the study(days 4— control samples were adjusted for the recovery 35),(S)-methoprene levels remained at or below of the MPM surrogate solution. Values ranged the MQL. from 62.8 to 116%,with an overall adjusted av- ALTOSID Pellets produced (S)-methoprene erage recovery of 92.2 ± 14%. The addition of residues that peaked at 2.0 µg/liter on day 7 and field spiked samples to fortified controls resulted then declined below the MQL after day 14(Fig. in an overall adjusted average recovery of 98.3 1).The overall pattern for Pellets was similar to ± 17.1%. that of ALTOSID Briquets. Climatological data: The daily maximum wa- (S)-methoprene residues in microcosms treat- ter temperature in the microcosm tanks ranged ed with experimental sand granules were first from 44.6 to 82.4°F (7-28°C), with an overall detected on day 1, averaging 0.35 µg/liter. On average of 53°F (11.7°C). The daily minimum days 2-35, (S)-methoprene levels in these mi- water temperature in the microcosms tanks crocosms fluctuated near the MQL(Fig. 1). ranged from 35.8 to 69.5°F(2.1-20.80C),with an Statistical analysis: A split plot in time ANO- overall average of 48°F(8.9°C). A thin layer of VA revealed a significant interaction between ' ice formed in the tanks on November 4 and 5, treatment and time of sampling,so residue data 1991,but was easily broken during the sampling from each sampling date were analyzed sepa- process and melted by the end of the day.Total rately. For purposes of statistical analysis, all accumulated rainfall for the study period (Oc- methoprene residue levels <0.20 µg/liter were tober 15 through November 19,'1991)was 3.14 assigned a value of 0.10 µg/liter, unless they oc- ih. (8 cm) plus 0.75 in. (1.9 cm) of snow on curred in a replicate containing residues,in which November 8, 1991. case 0.20 µg/liter was used to calculate the rep- Methoprene residues in fields samples: Aver- licate average. (This accounts for differences in age methoprene residues produced by each for- values given below compared to some of the mulation on each date are shown in Fig. 1.(Val- ' numbers shown in Fig. 1.) ues of 0.2 µg/liter in Fig, 1 indicate that On day 0 there was no significant difference methoprene levels present in all of the samples between any of the different methoprene for- collected on that date for that formulation were mulations. Residues from the A.L.L. treatment below the MQL.)No detectable methoprene res- (2.2 µg/liter) were significantly higher than the idues were found in any untreated control sam- other methoprene formulations on day 1.There ples with the exception of one sample on day 1 was no significant difference between the other (Fig. 1). We cannot explain the presence of this . treatments. measured residue, because this sample was col- A.L.L. and ALTOSID Briquets produced the lected,processed,and packaged for shipment ap- highest(S)-methoprene residues on day 2, 1.54 proximately 24 h before the application of meth- and 0.97 µg/liter, respectively. However, there oprene treatments to any of the microcosms. were no statistically significant differences be- In microcosms treated with A.L.L.(Fig.1),(S)- tween formulations on this day. On day 4, the methoprene residues averaged 2.2 µg/liter on day Briquet formulation produced the highest con- 1 and gradually declined to 0.23 µg/liter by day centration, 2.12 µg (S)-methoprene/liter, which 14. Following this date, residues in the A.L.L.- was significantly higher than all other treatments. treated microcosms remained at or below the On day 7,the 4.0 µg(S)-methoprene/liter con- MQL for the duration of the study. centration from the ALTOSID Briquet formu- The average(S)-methoprene concentration in lation was significantly greater than all other samples on day 1 after application of ALTOSID treatments.On this day,the level in ponds treat- Briquets was less than the MQL.(ALTOSID Bri- ed with Pellets,2.0 µg(S)-methoprene/liter,was quets are formulated with (R,S)-methoprene, a also significantly greater than the A.L.L.,XR Bri- 50:50 mixture of the R and S methoprene iso- quets,and sand granules,which were not signif- mers.All the other formulations used in this study icantly different from each other. contain only(S)-methoprene. To simplify com- The only statistically significant difference ev- parisons,the(S)-methoprene equivalent is shown ident on day 14 was between the ALTOSID Bri- in Fig. 1 and used in the text for ALTOSID Bri- quets (0.29 µg (S)-methoprene/liter) and the quets.)On day 2 the average value was 0.97 µg A.L.L.(<0.2 µg/liter).There were no significant (S)-methoprene/liter and increased to a high of differences between residues produced by any of 4.0 µg/liter on day 7.Residues subsequently de- the formulations on days 21, 28, or 35. clined to levels between 0.34 and 0.2 µg/liter Field quality control: Average(S)-methoprene from days 14 to 35. levels in the field quality control samples were (S)-methoprene residues were first detected in 4.8, 6.1,and 7.8 µg/liter for days 1, 14,and 35, ponds treated with ALTOSID XR Briquets at respectively.Overall average adjusted field spike day 2, when they averaged 0.70 µg/liter. recovery was 116 ± 16%, indicating that no I JUNE 1994 METHOPRENE CONCENTRATIONS IN FRESHWATER MICROCOSMS 207 4- 4 3 3 2s 2 UNTRF,ATFD 2 A.L.L. s 1 1 .3 0.47 -0. 0.2 0.2 0.2 0.2 0.2 0.2 03J 026 0.2 0.205 0 0 5 10 IS 20 25 30 35 0 5 10 15 20 25 30 35 ai 4 4 .4 W3 3- z My 2. x0 2- BRIQUETS 2 xR RRIQUF,TS r 1 1 e.7 0.34 0 B 0.2 0 &.127 0.12 0.2 0.2 0.2 �0 0 rrT n 0 5 10 15 20 25 30 35 1 S 10 15 20• 25 30 35 4 4 J 3 2 2 -*-PELLETS 2 �rGRANULES 1 1 ' 1 Q6 J3 0.2 0.2 0.2 .33 03 0.2 u4 03 0.2 04 0 0 0 5 10 1s 20 25 30 35 0 5 10 15 20 25 30 35 DAYS AFTER APPLICATION DAYS AFTER APPLICATION Fig.1. Mean(S)-methoprene concentrations(mg/liter)in untreated and ALTOSID-treated microcosms during the 35-day duration of the study. 208 JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION VOL. 10, NO. 2 150 Table 1. Geometric mean (S)-methoprene concentrations in freshwater microcosms during the 35-day field study. z100 Mean(S)- methoprene a concen- tration Formulation (µg/liter) W ALTOSID Liquid Larvicide 0.32 ALTOSID Briquets 0.32 ALTOSID XR Briquets 0.14 ALTOSID Pellets 0.24 0- __ SAN 801 I 1.3 GR 0.12 , 0 1 2 3 4 5 6 7 µg(S)-METHOPRENE/LITER(ppb) Fig. 2. Frequency distribution of(S)-methoprene and-discrete samples taken at various times after residues from 10 ALTOSID-treated microcosms from application will not necessarily be representative 8 postapplication sampling dates combined(1,2,4,7, Of this exposure (Clark et al. 1987, Jarvinen et 14�21,28,and 35 days). al. 1988,Parsons and Surgeoner 1991).A better approach from the point view of risk assessment methoprene degradation occurred during field is to use the median value for the exposure con- processing and shipping. centration. However, because our microcosm 'residue data are not normally distributed (Fig. DISCUSSION 2), the geometric mean is a better measure of central tendency than the arithmetic mean. (To Knuth(1989) found that field applications of calculate the geometric mean samples with a res- ALTOSID XR Briquets produced (S)-metho- idue below the MQL[<2 µg/literl were assigned prene levels of 0.39-8.8 µg/liter, similar to the a value of 1 µg/liter, as for the statistical analy- 0.2-6.0 µg/liter range observed in our samples. ses.) The geometric mean (S)-methoprene con- No sample collected in the course of the current centrations in microcosms treated with ALTO- study contained a residue in excess of 10 µg(S)- SID Briquets, XR Briquets, Pellets, and sand methoprene/liter(Fig.2).In fact,85%of the res- granules were all less than or equal to the mean idues measured in the 186 samples analyzed from concentration resulting from the A.L.L. appli- treated mesocosms were <_1 µg/liter. The sus- cation (Table 1). In fact, the values for all for- tained release formulations examined in this study mulations were substantially below the EEC for did not produce methoprene residues in excess A.L.L.(10 µg/liter).Consequently,we accept our of the EEC produced by application of A.L.L. hypothesis that use of these solid formulations (i.e., 10 µg(S)-methoprene/liter);indeed,for some does not expose nontarget organisms to metho- formulations they were considerably lower.These prene concentrations greater than those expected data support the fact that methoprene has a short or indeed resulting from A.L.L.application. We environmental persistence,even when applied in conclude that the use of these solid, sustained- sustained-release formulations. release methoprene formulations does not rep- One of the major concerns regarding the use resent an unacceptable risk to nontarget organ- of methoprene for mosquito control is its non- isms compared to the use of A.L.L. target effects.In order to assess possible nontar- get impacts, known methoprene concentrations ACKNOWLEDGMENTS likely to be found or measured in the field are compared to concentrations known to cause ad- The study as conducted by ABC Laboratories, verse effects in organisms exposed under anal- Inc., was intended to satisfy Good Laboratory ogous conditions.Acute and chronic studies used Practice (GLP) regulations and to comply with to assess a chemical's toxicity are usually con- protocols, methods, standard operating proce- ducted at constant exposure to unvarying ddres (SOPS), and sponsor-specified guidelines. amounts of chemical conditions quite different The quality assurance staff of ABC Laboratories from methoprene concentration changes ob- was responsible for all audits.The application of served after application in experimental micro- methoprene and collection of field samples was cosms (Fig. 1). It is well known that organisms performed by personnel of ABC Laboratories. respond to the area under the concentration curve, Personnel of the University of Mississippi Bio- JUNE 1994 METHOPRENE CONCENTRATIONS IN FRESHWATER MICROCOSMS 209 logical Field Station also assisted in collecting Logan,T. M., K. J. Linthicum,J. N. Wagateh, P. C. water samples and recording climatological data. Thande, C. W. Kamau and C. R. Roberts. 1990. We thank all of these people for the quality of Pretreatment of floodwater Aedes habitats(dambos) their work and their persistence in the conduct in Kenya with a sustained-release formulation of of this study. We also thank Jim Burleson and methoprene. J. Am. Mosq. Control Assoc. 6:736- Ms.Khanh Nguyen(Zoecon)for their invaluable 738' assistance in resolving critical analytical issues McKague,A.B.and R.B.Pridmore. 1978. Toxicity and Keith Solomon, University of Guelph, for co o saki and Bull. n to juvenile rainbow trout and coho salmon. Bull. Environ. Contam. Toxicol. 20: his constructive review of the manuscript. 167-169. Miura,T.and R.M.Takahashi. 1973. Insect devel- REFERENCES CITED opmental inhibitors. 3. Effects of nontarget organ- isms.J. Econ.Entomol.66:917-922. Anonymous. 1975. EPA registers "growth regulat- Parsons,J. T. and G. A. Surgeoner. 1991. Effect of ing" mosquito control pesticide. E.P.A. Environ. exposure time on the acute toxicities of permethrin, News,March 14, 1975. fenitrothion, carbaryl and carbofuran to mosquito - Batzer,D. P.and R. D.Sjogren. 1986. Potential ef- larvae.Environ.Toxicol.Chem. 10:1219-1227. fects of ALTOSID(methoprene)briquet treatments Quistad,G.B.,L.E.Staiger and D.A.Schooley. 1974. on Eubranchipus bundyi(Anostraca: Chirocephali- Environmental degradation of the insect growth reg- dae).J.Am. Mosq.Control Assoc.2:226-227. ulator methoprene.I.Metabolism ofalfalfa and rice. Clark,J. R.,P. W. Borthwick,L. R. Goodman,J. M. J.Agric. Food Chem. 22:582-589. Patrick,J.C.Moore and E.M.Lores. 1987. Com- Quistad,G.B.,L.E.Staiger and D.A.Schooley. 1975. parison of laboratory toxicity test results with re- Environmental degradation ofthe insect growth reg- sponses of estuarine animals exposed to fenthion in ulator methoprene.III.Photodecom position.J.Agric. the field. Environ.Toxicol.Chem. 6:151-160. Food Chem. 23:299-303. Dame, D. A., R. E. Lowe, G. J. Wichterman,A. L. Quistad, G. B., D. A. Schooley, L. E. Staiger, B. J. Cameron, K. F. Baldwin and T. W. Miller. 1976. Bergot, B. H. Sleight and K.J. Macek. 1976. En- Laboratory and field assessment ofinsect growth reg- vironmental degradation of the insect growth regu- ulators for mosquito control. Mosq. News 36:462- lator methoprene. IX. Metabolism by bluegill sun- 472. fish. Pestic. Biochem. Physiol. 6:523-529. ElFrien, E. G.,. T. Barber, S. C. a swi and A. L. Rathburn, C. B., Jr., E. J. Beidler, G. Dodd and A. Friend. fish a os analysis of the swimming be- Alfferty. 1979. Aerial applications of a sand for- methoprene offish exposed to the insect growth regulators mulation of methoprene for the control of salt marsh methoprene and diflubenzuron.Mosq.News 39:311- 314. mosquito larvae. Mosq. News 39:76-80. Floore,T.G.,C.B.Rathburn,Jr.,A.H.Boike,Jr.,H. Schaeffer,C. H. and E. F. Dupras. 1973. Insect de- M.Rodriguez and J.S.Coughlin. 1990. Small plot velopment inhibitors. 4. Persistence of ZR-515 in tests of sustained-release ALTOSID (methoprene) water.J. Econ.Entomol.66:923-925. pellets against Aedes taeniorhynchus in brackish wa- Schooley,D.A.and G.B.Quistad. 1979. Metabolism ter.J.Am.Mosq.Control Assoc. 6:133-134. of insect growth regulators in aquatic organisms,pp. Floore,T.G.,C.B.Rathburn,Jr.,J.C.Dukes,B.W. 161-176. In:M. A. Q. Khan, J. H. Lech and J. J. Clements,Jr, and A. H. Boike, Jr. 1991. Control Menn. (eds.). Pesticide and xenobiotic metabolism of Aedes taeniorhynchus and Culex quinquefasciatus in aquatic organisms. Am. Chem. Soc. Symp. Ser. emergence with sustained release ALTOSID sand 99. granules and pellets in saltwater and freshwater test Schooley,D.A.,B.J.Bergot,L.L.Dunham and J.B. plots.J.Am. Mosq.Control Assoc. 7:405-408. Siddall. 1975a. Environmental degradation ofthe Garg, R. C. and W. A. Donahue. 1989. Pharmaco- insect growth regulator methoprene (Isopropyl logic profile of methoprene,an insect growth regu- (2E,4E)-11-methoxy-3,7,1I-trimethyl-2,4-dodeca- lator,in cattle,dogs and cats.J.Am.Vet. Med.As- dienoate). 11. Metabolism in aquatic microorgan- soc. 194:410-412. isms.J.Agric. Food Chem.23:293-298. Gill,J. L. 1978. Design and analysis of experiments Schooley,D.A., K. M.Creswell,L. E.Staiger and G. in the animfil and medical sciences, Volumes 1-3. B.Quistad. 1975b. Environmental degradation of Iowa State Univ. Press,Ames. the insect growth regulator Isopropyl(2E,4E)-11- Jarvinen,A.W.,D.K.Tanner and E.R.Kline. 1988. methoxy-3,7,1 I-trimethyl-2,4-dodecadienoate Toxicity ofchlorpyrifos,endrin or fenvalerate to fat- (methoprene). IV. Soil metabolism. J. Agric. Food head minnows following episodic or continuous ex- Chem. 23:369-373. posure.Ecotoxicol.Environ.Safety 15:78-95. Siddall,J. B. 1976. Insect growth regulators and in- Knuth,M.L. 1989. Determination ofthe insect growth sect control:a critical appraisal.Environ.Health Per- regulator methoprene in natural waters by capillary spect. 14:119-126. gas-liquid chromatography.Chemosphere 18:2275- Sjogren, R. D., D. P. Batzer and M. A. Juenemann. 2281. 1986. Evaluation ofinethoprene,temephos and Ba- Kramer, V. L. and C. Beesley. 1991. Efficacy and cillus thuringiensis var.israelensis against Coquillet- persistence of sustained-release methoprene pellets tidia perturbans larvae in Minnesota.J.Am.Mosq. against Aedes mosquitoes in an irrigated pasture.J. Control Assoc. 2:276-279. Am.Mosq.Control Assoc. 7:646-648. Tietze,N.S.,P.G.Hester,J.C.Dukes,C.F.Hallmon, 210 JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION VOL. 10,NO. 2 T M.A.Olson and K.R.Shaffer. 1992. Acute toxicity Wright,J.E. 1976. Environmental and toxicological of mosquitocidal compounds to the inland silverside aspects of insect growth regulators.Environ.Health Menidia beryllina.J.Fla.Mosq.Control Assoc.63: Perspect. 14:127-132. 1-6. Journal of the American Mosquito Control Association, 10(2):21 1-221, 1994 Copyright © 1994 by the American Mosquito Control Association,Inc. EFFECTS OF THE INSECT GROWTH REGULATOR (S)-METHOPRENE ON THE EARLY LIFE STAGES OF THE FATHEAD MINNOW PIMEPHALES PROMELAS IN A FLOW-THROUGH LABORATORY SYSTEM DOUGLAS H. ROSS,' PAUL COHLE,2 PATRICIA RITCHIE BLASE JAMES B.BUSSARD2 AND KATHY NEUFELD2 ABSTRACT. This study assessed the effect of the insect growth regulator(IGR)(S)-methoprene on fathead minnow (Pintephales promelas) early life stages. Newly spawned (:524 h) minnow eggs were continuously exposed to(S)-methoprene concentrations of 13, 23, 48, 84, and 160 µg/liter for 37 days in a 2-liter proportional diluter system. No significant reductions(P > 0.05)were detected at any test concentration for hatchability, fry survival, or total survival when compared to controls. Significant - reductions(P<0.05)in length and weight were detected at the 2 highest mean measured test concentrations compared to controls.The maximum acceptable toxicant concentration(MATC)limits,the no-observed effect concentration(NOEL),and the lowest observed effect concentration(LOEC),based on analyses of fry length and weight,were 48 and 84 µg/liter,respectively.The point estimate MATC value(the geometric mean of the NOEC and LOEC)was calculated to be 63.5 µg/liter. INTRODUCTION (Cope)) to be 2.781 mg/liter (278 x label rate). And in a study of swimming behavior, Ellgaard The first solid, sustained-release methoprene et al.(1979)observed no alteration of locomotor formulation(ALTOSID®Briquets)received U.S. _activity in either the goldfish(Carassius auratus) Environmental Protection Agency (EPA) regis- or the mosquitofish(Gambusia affinis(Baird and tration for mosquito control is 1978.Since that Girard)) at 0.2 mg methoprene/liter, 20 x the time, this product's label, and labels of subse- maximum label rate. quent solid formulations (ALTOSID XR Bri- The primary objective of this study was to quets and Pellets) have been required to carry estimate the maximum acceptable toxicant con- the following precautionary statement: "Do not centration(MATC)limits for(S)-methoprene us- apply to known fish habitat(s)".This precaution ing what is believed to be the most critical and was required due to gaps in Zoecon Corpora- sensitive life stage (egg to juvenile stage) of the tion's fish toxicity database rather than any dem- fathead minnow (Pimephales promelas Rafin- onstrated toxicity to fish. Indeed, numerous esque)(Environmental Protection Agency[EPA] studies show that methoprene has little if any 1978a, U.S.Congress 1979).This objective was effects on several fish species. achieved by measuring the effects of(S)-meth- Madder and Lockhart(1978)exposed rainbow oprene exposure on hatchability of eggs,fry sur- trout (Salmo gairdneri Richardson) to metho- vival,and fry growth as determined by compar- prene levels ranging from 0.625 to 10.0 mg/liter ison between control and (S)-methoprene (ppm), which are 62.5-1,000x the maximum exposure data. label rate(10 µg/liter[ppb]).At these exaggerated levels they observed visible lethargy among the test fish and recorded a dose-dependent decline MATERIALS AND METHODS in blood glucose;however,no mortality was not- The biological methods used for this early life ed. McKague and Pridmore (1978) determined stage study with (S)-methoprene are basically the methoprene 96-h LCSos for rainbow trout and those described in the"Proposed Recommended coho salmon (Oncorhynchus kisutch) to be 106 Bioassay Procedure for Egg and Fry Stages of and 876 mg/liter, respectively (10,600 and Freshwater Fish" (EPA 1972') and "Proposed 8,600 x the maximum label rate). In another New Standard Practice for Conducting Fish Ear- study, Tietze et al. (1992) determined the 48-h ly Life Stage Toxicity Tests"(Anonymous 1983). LC,,for the inland silverside(Menidia beryllina The 37-day study, which began on August 24, 1992, and concluded on September 30, 1992, was conducted in accordance with U.S.EPA FI- 'Technology Development, Zoecon Corporation, 12200 Denton Drive, Dallas,TX 75234. Present ad- dress:Famam Cos.,Inc.,301 w.Osborn,Suite 2000,Phoenix,AZ 85013. ,Environmental Protection Agency. 1972. Pro- 2 Aquatic Toxicology Programs Division,Analytical posed recommended bioassay procedure for egg and Biochemistry Laboratories,7200 East ABC Lane,Co- fry stages of Environmental freshwater Researchfish.Unp orys ed manuth,MNpt lumbia,MO 65202. 211 r � 212 JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION VOL. 10, NO. 2 FRA Good Laboratory Practice (GLP) stan- test solution split into the 4 replicate chambers dards. (designated as replicates A, B, C, and D) was The MATC (EPA 1978b) limits, as used in verified by volumetric measurement before study this report, are the no-observed effect concen- initiation. Eggs were incubated in glass incuba- tration (NOEC) and the lowest observed effect tion cups,constructed from 9-cm diam glass jars concentration(LOEC).The upper limit,or LOEC, with 40-mesh Nytex screen replacing the bottom. is the test concentration that produces at least These incubation cups were suspended in each one statistically verifiable adverse effect upon a replicate test chamber. To facilitate circulation measured parameter during the study (Anony- of test solution around the eggs, the incubation mous 1983). The lower limit, or NOEC, is the cups were oscillated vertically(3-6 cm) in each highest test concentration producing no statis- test chamber by a rocker arm apparatus driven tically verifiable adverse effect on any of the mea- by a low rpm electric motor(Mount 1968). Du- sured parameters. In this study, the measured plicate glass aquaria used for egg hatching and parameters were hatchability, fry survival, total as growth chambers were divided by a glass plate survival, and growth(standard length and blot- into 2 separate replicate chambers(i.e.,no water ted wet weight). An adverse effect is one that is exchange between replicates).The inside dimen- a statistically significant(P<_ 0.05;see below for sions of each replicate chamber averaged 30.5 x specific procedures)reduction from control data 15.7 cm with an average water depth of 24.6 cm, for the parameter being measured.The point es- yielding an approximate 1 1.8-liter chamber vol- timate MATC value is defined as the geometric ume. These chambers were constructed of glass )mean of the LOEC and the NOEC. plates bonded together with silicone sealant. All Test compound: The (S)-methoprene techni- chamber drains were covered with stainless steel cal (lot #23698), had a sample purity of 91.4% screen to prevent fry escape. (Zoecon Analysis Report,sample#T03562).Di- Control dilution water, along with test solu- luter system stock solutions and both method- tion, was delivered to the replicate chambers at validation and quality control spiking solutions an average rate of 92 liters/day/replicate. This were prepared from this sample.It was also used was equivalent to adding^-7.8 test chamber vol- for preparing GLC reference standards for the umes per day. Flow-through biomass loading method validation and the preliminary studies. levels ranged from 0.029 to 0.059 g/liter/day at The first (lot #311-126) of 2 (S)-methoprene study termin4tion. analytical standards(purity of both was specified All test aquaria were immersed in a thermo- as 93.19%)was used during preliminary testing. statically controlled water bath to maintain a The second (lot #311-138) was used during the temperature of 25 ± 2°C. Developing embryos definitive early life stage study. A primary ana- and newly hatched fry were shielded from excess lytical stock solution was prepared in iso-octane. light exposure until 3 days posthatch. At this Subsequent dilutions in iso-octane were pre- time,all test aquaria were illuminated by an elec- pared for use as GLC reference standards. The tronically controlled fluorescent light system that primary analytical stock was also used as a ref- provided 30-min simulated dawn and dusk tran- erence standard for the gas chromatograph/mass sition periods.This system was programmed for spectrometer (GC/MS) analysis. Both the first a 16 h light:8 h dark photoperiod. Light inten- and 2nd(S)-methoprene analytical standards were sity ranged from 442 to 574 lux (41-53 foot- kept in freezer storage when not in use.All GLC candles)at the water surface. and GC/MS reference standard solutions, stock Test procedure—chemical and physical: Di- solutions, and spiking solutions used for con- luter test system water was obtained from a deep ducting this study were refrigerated when not in well. A portion of this well water was passed use. through a reverse osmosis system and then Diluter test system: A proportional diluter blended back with well water to a total hardness system described by Mount and Brungs (1967) of approximately 130-160 mg/liter (as CaCO.) with a Hamilton Microlab8 Model 420(syringe) and a pH of approximately 8.0. Water quality Dispenser was used for the intermittent intro- parameters were measured on study days 0, 1, duction of(S)-methoprene test solutions to 4 rep- 7, and weekly thereafter. Temperature and dis- licate test chambers per concentration. During solved oxygen were measured in the control,ve- each diluter cycle,flow-splitting chambers divid- hicle blank(water+solvent),and each test level. ed the ^-2.0-liter volumes delivered to each of Conductivity,pH, hardness,and alkalinity were the 5 test levels,vehicle blank,and dilution water measured in the control,low,and high test con- control into 2 aliquots. Each aliquot was again centration. For the test concentrations and con- divided in half before being delivered to the rep- trols being monitored for water quality, mea- licate test chambers, adding ^-500 ml to each surements were taken for only one of the 4 replicate per diluter cycle. The accuracy of the replicate chambers per analysis day.The cham- r v t J JUNE 1994 METHOPRENE/FATHEAD MINNOW EARLY LIFE STAGE STUDY 213 hers monitored on days 0, 1, 7, 15, 21, 28, and ferred from the reservoir to the chemical mixing 37 were the A, B, C, D, A, B, and C replicates, box on the diluter by the Hamilton(syringe)dis- respectively.Monthly measurements of total or- penser.In the mixing box this aliquot was diluted ganic carbon and suspended solids were also per- to a volume of 4,050 ml with dilution water to formed. create the high nominal test concentration of 200 A digital thermometer(from VWR Scientific) µg/liter. Approximately 2,000 ml of the 200-µg/ was used for the temperature measurements taken liter solution were added directly to the high test in conjunction with dissolved oxygen measure- level chambers. The remainder of the 200-µg/ meats. Dissolved oxygen was measured with an liter solution was divided into aliquots of 1,000, Orion Model 820 dissolved oxygen meter, pH 500, 250, and 125 ml. Each aliquot was diluted with a Beckman (k12 pH/ISE meter, and con- to ^-2,000 ml with dilution water to create test ductivity with a Corning Check Mate 90 Con- solutions for the 4 lower test levels. This 50% ductivity/TDS meter. Hardness was determined proportional dilution scheme produced the 5 by an EDTA colorimetric titration method and nominal (S)-methoprene test concentrations of alkalinity by an HISO, colorimetric titration 13, 25, 50, 100, and 200 µg/liter. method (Anonymous 1989). Temperature was (S)-methoprene test solutions flowed through monitored in a centrally located test chamber the exposure aquaria for 7 days before the ini- (the B replicate of level 2)•on a continuous basis tiation of the definitive study. Actual (S)-meth- with a Rustrak® Ranger®temperature data log- oprene test concentrations were measured by ger and was checked twice daily with a mercury means of gas-liquid chromatography (GLC) on thermometer. study days 0, 1, 7, 15, 21, 28, and 37 (study (S)-methoprene was introduced into dilution determination). water in the diluter system's chemical mixing The DMF served as a vehicle(solvent) to fa- box from a stock solution prepared in dimethyl- cilitate the mixing of the test substance with wa- formamide(DMF).The concentration of the(S)- ter. Because the test solution for level 5(highest methoprene diluter stock solution was calculated test level)was delivered undiluted from the mix- as follows: ing box, this level also had the highest DMF concentration(0.050 ml of stock/4.05 liter HZO C, = Concentration of diluter stock solution = 0.012 ml/liter). Vehicle blank solution was V, = Volume of diluter stock injected into prepared by injecting 0.025 ml of DMF into the chemical mixing box(0.050 ml) vehicle blank splitter cell that received an av- CZ = Desired concentration of(S)-methoprene erage volume of 2.03 liter of dilution water per in chemical mixing cell (same as level 5, cycle. This resulted in a DMF concentration of 200 µg/liter) 0.012 ml/liter, the same as in level 5. VZ = Volume of chemical mixing cell(4,050 ml) Test procedure—analytical: The (S)-metho- _ CZVZ (200 µg/liter)(4,050 ml) prene analytical method was validated in test C = water before the definitive testing began. Test V, 0.050 ml concentrations were determined from the antic- C, = 16,200,000 µg active ingredient/liter ipated test concentrations of the early life stage C, = 16,200 mg AI/liter. study. Analysis of the test water samples used Zoecon Corporation's proprietary method Diluter stock solutions were prepared by dis- (Chemical Analytical Procedure #323). solving 1,772 mg of(S)-methoprene technical in Concentrations of(S)-methoprene were mea- DMF and bringing the solution to a total volume sured in the 5 test levels on study days 0, 1, 7, of 0.100 liter. At a purity of 91.4%,the concen- and weekly thereafter by means ofGLC.Control, tration of(S)-methoprene active ingredient was vehicle blank, diluter stock solution, and (S)- 16,200 mg/liter. For the definitive study, 0.1- methoprene-fortified quality control water sam- liter batches of diluter stock solution were pre- ples were analyzed on each sample day. pared at 8- to 13-day intervals. Stock solution On each sample day, approximately 250-ml was added to the diluter test system reservoir in aliquots were collected from both replicates A ^-20-100-m1 aliquots.Aliquots were added at 4- and B (or replicates C and D) of each test con- to 9-day intervals.After filling the reservoir,ex- centration and combined into a 500-m1 total tra stock was stored in a refrigerator, protected sample. Aliquots were taken subsurface with a from light,until needed.The stock solution res- 100-ml Class A volumetric pipet from the ap- ervoir on the diluter consisted of an amber bottle proximate center of the chambers. Replicates A connected to the syringe injector via tetrafluoro- and B were sampled on days 0, 7, 21, and 37, ethylene(TFE)tubing. and replicates C and D were sampled on days 1, Each time the diluter cycled, 0.050 ml of the 15, and 28, respectively. 16,200-mg/liter diluter stock solution was trans- Samples were analyzed for(S)-methoprene with 214 JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION VOL. 10,No. I a Hewlett-Packard 5890 Series II gas—liquid Column head pressure: 8 psi chromatograph equipped with a flame ionization GC temperature program detector(FID). The chromatographic data were Initial: 80°C, hold for 2 min collected and stored with a DEC MicroVaxIs 3800 Final: 250°C, hold for 10 min computer using VAX® MULTICHROMO soft- Rate = 10°C/min. ware. System operating parameters were: FSOT, Test procedure—biological: Three prelimi- Column: Supelco SPB-608 Bonded m x 0.53 mm x 0.ed ed µm film nary tests were conducted to estimate the (S)- hickness methoprene concentration range for the defini- t Detector: hic tive study. The first test,which ran for 25 days, Temperatures included a control (water only), vehicle blank Injector Temperatures (solvent+ water)and the nominal(=target)(S)- Inject or 300°C methoprene test concentrations of 130,250,500, Detect2 min 1,000,and 2,000 µg/liter.The 2nd range-finding Column(initial) 80°C, hold(final) 250°C, hold 2 min study,which ran for 30 days,included a control, Column( vehicle blank,and nominal concentrations of 31, Rate— 1 fina min Gas flows 130,and 500 µg/liter. The control and test con- Gas ml/min (makeup) centrations in both tests consisted of 2 replicate He: ^ ml/min(column) chambers. At initiation, each chamber received 2. H2: 40.3 ml/min 20 fathead minnow eggs, except for the control Air: 40 ml/min replicates in the 2nd study,which each received Injection volume: 3 µl. 22 eggs.Eggs used in the first study were <27 h postspawn.Eggs used in the 2nd study were eyed Calculations of (S)-methoprene concentra- and approximately 48 to 72 h postspawn.Hatch- tions were performed using the external standard ability, survival, and growth were the primary analysis function of a DEC MicroVax® 3800 parameters observed for toxicant effects. computer equipped with VAX® MULTI- For each of the 3 exposure concentrations in CHROMO software. Concentrations of(S)- the 2nd study, 2 additional replicate chambers methoprene in the samples were determined di- that did not contain eggs or fry were also in- rectly from the standard curve by the following cluded, Analytical sampling was periodically equation: performed on these chambers along with the µg/ml equivalents from standard curve equation chambers containing fish to determine if the x volume for analysis in ml presence of fish and the accompanying organic matter from feeding and waste products would volume extracted in ml cause a decrease in (S)-methoprene concentra- 1 000 ng tions. In the chambers containing fish, mean _ x ng/ml = µ/liter= ppb. measured concentrations ranged from 74 to 100/o µg of nominal.Mean measured values in the cham- Mass spectrometry analysis: On each sample bers without fish ranged from 74 to 80%of nom- day the sample extract from the high test level inal. was analyzed for confirmation of(S)-methoprene A 3rd preliminary test was conducted for de- using a Finnigan-MAT 5100 gas chromatograph/ termining solubility at the proposed high nom- mass spectrometer(GC/MS). The system oper- inal test concentration of 200 µg/liter. A Boni- ating parameters were as follows: cator(Baxter S/PIs Ultrasonic Cleaner)was used as the mixing box to facilitate (S)-methoprene Mass spectrometer dissolution.No eggs or fry were added to the test Electron multiplier(eV): 1,700-2,000 chambers. A slight surface film was observed at Source temperature: 20°C the high test level chambers;however,analytical Mass scan range: 400-700 daltons measurements of the high level were 95 and 100% Scan rate: 1 sec/decade of nominal. Gas chromatograph Based on results from the 3 preliminary tests, Interface temperature: 250°C the nominal test concentrations of 13, 25, 50, Injection mode: Splitless 100, and 200 µg(S)-methoprene/liter were cho- Injection volume: 1 µl for standards, 2-3 µl sen for the definitive study. for samples The definitive investigation used newly Injector temperature: 250°C spawned fathead minnow eggs (s24 h post- Column: Supelco SPB-608 Bonded FSOT, spawn) obtained from the Analytical Biochem- 15 m x 0.53 mm x 0.50 µm film istry(ABC) Laboratories' in-house culture. The thickness eggs were spawned onto stainless steel tiles.The 1 1 JUNE 1994 METHGPRENE/FATHEAD MINNOW EARLY LIFE STAGE STUDY 215 eggs from 4 spawning tiles(^-900 eggs total)were with the addition of eggs on study day 0 and removed by gently rolling them off the tiles under continued until termination on day 37. water using the thumb and/or fingers. At.least 3 Fry growth was measured as a function of stan- males and 3 females were involved in the pro- dard length and blotted wet weight on study day duction of these 4 spawns.Eggs were transferred 37. All surviving fish.were sacrificed in tricaine to the incubation cups by drawing 2 at a time methanesulfonate(MS-222). They were blotted into a small bore glass pipet and gently placing on paper towels to remove excess moisture,then them into the cups until all cups in the test system weighed on a Mettler PM200 balance. The bal- contained 2 eggs.This impartial placement pro- ance was interfaced with a computer and the fish j cess was completed with the addition of one egg weights were entered on a computer worksheet to each cup, bringing the total number of eggs via direct data capture using the Lotus Measure0 ` per replicate to 25. Observations of egg mortal- program^integrated with the Lotus 1-2-3®com- ity, ascertained by a distinct change in egg col- puter programs Standard lengths were measured oration or appearance,were recorded daily.Upon by placing the fish directly on a Calcomp® dig- discovery,dead eggs were removed from the cups itizing tablet and electronically marking the dis- and discarded. tance from the tip of the snout to the caudal Hatch began on study day 3 and was complete peduncle with a puck. The lengths were directly by study day 9, at which time the fry were re- entered into a data worksheet via the Sigma- leased from the incubation cups into the test Scan® measurement program.6 chambers.Feeding began on study day 3.For the Statistical analyses: Duplicate test aquaria per first week of feeding and throughout the study, concentration were arranged in one row on one the fry were fed brine shrimp(Artemia sp.)nau- tier using a random number table to assign spe- plii.Beginning on the 8th day of feeding,Salmon cific test concentrations. Each aquarium con- Starter® fish food was added to the diet. tained 2 individual replicate chambers for a total Food was usually added to the test chambers of 4 replicate chambers per concentration. This 3 times per day during the week. The fish were arrangement provided a nested experimental de- fed 3 times per day during the first weekend of sign. Observations and/or measurements were feeding and 2 times per day on succeeding week- made on the individual fish for continuous data ends. All chambers received the same amount (standard length and blotted wet weight)and the of food during each feeding.The amount of food replicate chamber(pooled within test concentra- was increased as the fish increased in size. Suf tions)for hatchability and survival data. ficient food was added to allow for at least 30 Hatchability and survival data were analyzed using frequency analysis comparing each test min of feeding. On study day 36, however, the concentration to the appropriate control. This fish were not fed in order to allow at least 24 h analysis was coupled with a one-tailed Fisher's without feeding prior to weighing and measuring exact test and the chi-square statistic to deter- the fish at termination on day 37. mine those concentrations exhibiting a response Abnormal behavioral or physical changes and significantly less than that of the control. Before mortality were monitored by visually inspecting analysis with the exposure concentrations, con- the fry in each growth chamber daily and re- trot and vehicle blank responses were combined cording the data. Upon discovery during daily into a pooled control where a 2-tailed Fisher's observations, dead fry were removed and dis- exact test indicated no significant difference be- carded.All test chambers were siphoned as need- tween them. ed to remove fecal material, excess food, and Growth data were assessed by a one-way anal- biological growth.In order to decrease biological ysis of variance(ANOVA)procedure,appropri- oxygen demand in the test chambers, the sides ate for a nested experimental design, similar to of all chambers were scraped as needed to re- that described by McClave et al.(1981).Control move accumulated biological growth. and vehicle blank responses were compared for Hatchability, fry survival, total survival, and significant differences using a 2-tailed Student ! fry growth (standard length and blotted wet 1-test. If no significant differences were detected weight)data were collected for statistical analy- ses. Hatchability was analyzed at study day 9, which was the end of the hatching phase. Fry <Lotus Measure® Program. 1986. Lotus Devel- survival was analyzed at study day 37 (test ter- opment Corporation,Cambridge,MA. mination).The interval for fry survival began on s Lotus 1-2-3®, Release 2.2 1989. Lotus Devel- day 3 with the onset of hatch and ended on day opment Corporation,Cambridge,MA. 37 with study termination.Total survival,which 6 Sigma-Scan© Version 3.90. The Scientific Mea- ineluded both egg and fry survival,was analyzed surement Program. 1988. Jandel Scientific, Corte at study day 37.The total survival interval began Madera,CA. 216 JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION VOL. 10,NO. 2 ' Table 1. Chemical characteristics of blended water used by ABC Laboratories Aquatic Toxicology Programs Division. Monthly/weekly screens' Hardness 142-150 mg/liter as CaCO, Alkalinity 154-164 mg/liter as CaCO, pH 8.0-8.2 Conductivity 331-389 µS/cm (or µMhos/cm) Dissolved oxygen(DO) 7.1-7.9 mg/liter Total organic carbon(TOC) ND2-1.33 mg/liter Suspended solids(SS) 0.1-2.6 mg/liter 'Represents value(s)measured during the testing period.Hardness,alkalinity,pH,conductivity,and DO measured in control test chambers.TOC and SS measured in raw dilution water. ND-none detected.Detection limit= 1.00 mg/liter. between these 2 groups,they were combined into for test levels 1,2,3,4,and 5,respectively(Table a pooled control before further analyses with the 3). These values ranged from 80 to 100%of the exposure concentrations.A Dunnett's one-tailed nominal test concentrations. Diluter stock so- means comparison procedure was used to deter- lutions, analyzed under the same sampling +, mine those exposure concentrations exhibiting schedule, averaged 16,500 mg/liter, which rep- responses significantly less than that of the ap- resented 102%of the nominal stock concentra- propriate control (Dunnett 1955). For the con- tion of 16,200 mg/liter(Table 3).Recoveries from trol, vehicle blank, and each test concentration, fortification samples prepared on each sample histograms and a Shapiro-Wilk normality lest day at the nominal concentrations of 11.6, 58, statistic were generated to assess departures from and 209 µg/liter averaged 107, 98, and 98% of normality. Should the normality test indicate a nominal, respectively. deviation from strict normality,the data for each GC/MS analytical confirmation: For each concentration would be examined for indications sampling day, GC/MS analysis of extract from of central tendency. In cases where the assump- the high tiest concentration confirmed the pres- tions for an ANOVA hold entirely or even ap- ence of(S)-methoprene in each sample.This con- proximately,the ANOVA is generally the more elusion was based on comparison between the efficient statistical test for detecting departures standard and the samples for retention time and from the null hypothesis(Sokal and Rohlf 1973). characteristic ions. If no differences (either statistical or, more im- Water quality: Values for conductivity, pH, portantly,biological)were found between aquar- hardness, and alkalinity, measured in a single is in the same treatment, then the variability replicate of the control,low,and highest test con- among replicates within treatment,regardless of centration on days 0, 1, 7, 15, 21, 28, and 37, aquaria,was used as the error term for the Dun- are shown in Table 1. Dissolved oxygen mea- nett's test. surements ranged from 6.3 to 7.9 mg/liter (at All statistical analyses were performed using 25°C),representing approximately 80-100%ox- PC DOS SAS/STATS,7 with conclusions of sta- ygen saturation,respectively.Water temperature tistical significance based upon P s 0.05. ranged from 23.9 to 25.0°C. All values for these parameters fell within normal historical ranges RESULTS (ABC Laboratories, unpublished data). Time to hatch: Hatch began on study day 3 Method validation: Results or the method val- and was completed by day 9.There was no con- idation are presented in Table 2. Fortification centration-related delay of time to hatch(Fig. 1). concentrations were prepared in duplicate and Hatch was >-90% complete in the control, ve- ranged from 2.32 to 2,780 µg/liter.The average hicle blank, and all test levels by day 6. Day 0 recovery for method validation samples was 99.0 posthatch was designated as study day 7,as this ± 6.9%. is when>_95%of the eggs in all nonconcentration GLC analytical measurement of test concen- affected test levels (control, vehicle blank, and trations: Mean measured (S)-methoprene con- test levels 1-3) had hatched. No effect on time centrations were 13,23,48,84,and 160 µg/liter to hatch was indicated for the 2 highest test lev- els, 4 and 5. However, because growth effects were later demonstrated at these levels,they were 'PC DOS SAS/STAT. Release 6.04. 1988. SAS considered concentration-effect levels and were Institute,Inc.,Cary,NC. not used in the determination of day 0 posthatch. /:Table 1994 METHGPRENE/FATHEAD MINNOW EARLY LIFE STAGE STUDY 217 2. Fortifications and recoveries of(S)- librium. It was also noted in a single fish that hoprene in aquatic test water during the one eye was unusually small when compared to method validation. the other eye, which appeared to be of normal Fortifi- Measured size. This fish was not abnormal in any other cation concen- Per- respect. Physical and behavioral abnormalities level tram cent were sporadically observed in the control, ve- hicle blank, and in all 5 test levels during the (µgI (µg/ recov- study and involved only a few fish. It is not un- Sample liter) liter) eryl usual to observe a few abnormalities in control Control Az - ND' - and vehicle blank fish (as well as in exposure Control BZ - ND' - fish)during an early life stage study.No sublethal Level IA2 27.8 26.7 96 abnormalities appeared to be due to the test sub- Level 1132 27.8 26.6 96 stance. Level 2A2 278 266 96 Control and vehicle blank comparison: Hatch _ Level 2132 278 272 98 in the control and vehicle blank was 88 and 91%, Level 3A2 2,780 2,630 95 respectively.Fry survival on day 37 was 94%in Level 3B2 2,780 2,600 94 the control and 92%in the vehicle blank. Total Low spike A" 2.32 2.65 114 survival on day 37 was 83% in the control and Low Spike B° 2.32 2.43 105 84%in the vehicle blank. Statistical analyses in- Average recovery for method validation samples=99.0± dicated no significant difference (P > 0.05) be- 6.9%. tween the control and vehicle blank for hatch- From method check(method validation)samples analyzed ability,fry survival,or total survival.Therefore, on June 16, 1992. ND-not detected. control and vehicle blank data were pooled for Analysis performed during the second preliminary study. each of these 3 parameters before further anal- on July 28, 1992(study day 28). yses with data from the test concentrations. Mean standard length of the fish in the control and vehicle blank was 23.6 and 23.5 mm, re- Morphological and behavioral abnormalities: spectively. Mean blotted wet weight of the con- Sublethal physical and behavioral abnormalities trol and vehicle blank fish was 0.239 and 0.231 noted in the fish during the study included body g, respectively. Based on 1-tests, no significant curvature,quiescence,erratic swimming pattern, difference was detected between the control and .. resting on the chamber bottom,and loss of equi- vehicle blank for either length or weight (P > Table 3. Measured concentrations of(S)-methoprene during the early life stage toxicity study with fathead minnows. Measured concentration(µg/liter) Sample Repli- Con- Vehicle Level 1 Level Level Level Level 5 Stock r> day cate trol blank' (13)2 (25) (50) (100) (200) (1.62 x 101) 0 AB ND' <6.18 -4 22 47 98 170 1.69 x 10' 1 CD ND <6.18 145 26 50 77 160 1.68 x 10' 7 AB ND ND 14 24 50 88 160 1.64 x 107 15 CD ND ND 11 22 47 90 170 1.57 x 107 21 AB ND ND 12 22 46 76 150 1.65 x 107 28 CD ND ND 13 24 49 84 170 1.68 x 107 37 AB ND ND 13 24 48 78 150 1.63 x 107 Mean - - 13 23 48 84 160 1.65 x 107 ± SD - - 1.17 1.51 1.57 8.12 9.00 4.14 x 101 %CV6 - - 9.0 6.6 3.3 9.7 5.6 2.5 %nominal - - 100 92 96 84 80 102 Min. - - 11 22 46 76 150 1.57 x 107 Max. - - 14 26 50 98 170 1.69 x 107 '"Less than"values represent minimum quantifiable limit for each analysis day. Nominal concentrations given in parentheses are in µg/liter;measured values in these columns are also in µg/liter. ND-not detected. No value reported due to suspected contamination of sample. Reanalysis data.Initial analysis yielded questionable result. "CV=coefficient of variance. 218 JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION VOL. 10,NO. 2 , 100% 75% DAY + 09 1118 O 50 .7 °� Eaa ❑6 x ❑5 25% 4 ®3 0% CONTROLS 13 23 48 84 160 MEAN MEASURED µg(S)-METHOPRENE/LITER(ppb) Fig. 1. Time to hatch for fathead minnow eggs at different(S)-methoprene concentrations during the early life stage toxicity study. 0.05). Control and vehicle blank data for these Growth parameters: Mean standard lengths parameters were also pooled before analyses with and blotted wet weights (±SD) in the pooled data from the test concentrations. controls and the mean measured test Concentra- Hatchability and survival: Hatch and survival tions appear in Fig. 3. Significant (P <_ 0.05) in pooled controls and the mean measured test length and weight reductions occurred at the 84 concentrations are shown in Fig. 2. The statis- and 160 µg/liter test concentrations when com- tical analyses indicated no significant reduction pared to the pooled controls. (P > 0.05)in hatchability, fry survival, or total MA TO Statistical analyses of hatchability,fry survival at any test level when compared with survival, total survival, and growth (length and the pooled controls. weight) indicated tha> only the latter, namely 100% 93% 93% % 90% 92% 90%91% 91% % 88 7% 9% °� 1% 2% 9 80% z 60% W U PW. 40% 20%- N%EGG HATCH ❑%FRY SURVIVAL®%TOTAL SURVIVAL 0% Controls 13 23 48 84 160 MEAN MEASURED µg(S)-METHOPRENE/LITER(ppb) Fig. 2. Percent egg hatch, fry survival, and total survival of fathead minnows exposed to(S)-methoprene during the early life stage toxicity study. JUNE 1994 METHGPRENE/FATHEAD MINNOW EARLY LIFE STAGE STUDY 219 27- Table 4. Margins of safety for fathead A minnow early life stages provided by o xs different ALTOSID formulations. + 2.1.5 Mean(S)- 40 •' •' _ x3 methoprene � concen- ALTOSID tration' Margin of a 21 - .4 formulation (µg/liter) safety2 Briquet 0.32 196 19 - Liquid Larvicide 0.32 196 XR Briquet 0.14 466 17 Pellet 0.24 260 CONTROLS 13 23 46 84• 160• Ross et al.(1994). , j 2 Margin of safety=MATC/mean(S)-methoprene concen- tration. 330 insects.Consequently,methoprene would not be B expected to interfere with the morphological de- 300 velopment offish.Thus,we were somewhat sur- zso s prised to observe adverse growth effects in this 4 study.However,it must be remembered that ear- 200 ` ly life stages(vs.more mature fish)are employed 0 130 , in these tests because of their acute sensitivity to chemical substances. The effects observed are 100 likely due to some physical phenomenon such as interference with cell membranes, rather than so any endocrine activity of the IGR on the fish(K. o Solomon, personal communication). Controls 13 23 46 84• 160' The Quistad et al.(1976)study of methoprene MEAN MEASURED 1,6(9)-METHOPRENE/1-1TER(ppb) metabolism in fish demonstrates the tolerance of Fig. 3. A. Mean standard length(±SD); B. Mean these animals to methoprene.Bluegill sunfish ex- blotted wet weight(±SD)of fathead minnow fry after posed to radiolabeled methoprene rapidly me- 30 days posthatch exposure to(S)-methoprene during tabolized the compound. The metabolites enter the early life stage toxicity study. An asterisk (•) in- the carbon pool and become incorporated into dicates a statistically significant(P<_ 0.05)reduction various cell components such as cholesterol and y at the indicated concentration compared to controls. fatty acids.After extended methoprene exposure, only 0.1%of the radiolabel in these fish was iden- growth,was adversely affected by the highest(S)- tified as methoprene or its known metabolites. methoprene concentrations. Based on these re- The rest was incorporated into normal biochem- sults,the NOEC and the LOEC were determined icals, which are natural components of the or- to be 48 and 84 µg/liter,respectively(see Fig.3). ganisms' biochemistry and considered to be The NOEC and LOEC represent the MATC lim- completely innocuous. its for an early life stage toxicity study.The point A major concern in the use of mosquito lar- estimate MATC value,defined as the geometric vicides, including methoprene, is their impact mean of the NOEC and LOEC, was calculated on nontarget organisms, including fish. These to be 63.5 jig/liter. possible effects are usually assessed by compar- ing known concentrations likely to be found or DISCUSSION measured in the field with those known to cause adverse effects in organisms exposed under anal- The insect growth regulator(IGR)methoprene ogous conditions. is an analogue of and mimics the action of insect This chronic early life stage study was con- juvenile hormone. When applied to a holome- ducted using constant exposure to unvarying tabolous insect prior to pupation, methoprene methoprene concentrations—conditions quite interferes with metamorphosis during the pupal different from those observed in a recent study stage and prevents normal adult emergence(Sid- of methoprene formulations applied to experi- dall 1976). The nature and degree of metamor- mental microcosms (Ross et al. 1994). In that phosis observed in some vertebrate species(e.g., study,the highest measured daily(s)-methoprene amphibians, fish) is quite different from that in concentration was about 4 µg/liter(in a micro- , 220 JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION VOL. 10,NO. 2,; corm treated with an ALTOSID Briquet).Com- to fish eggs, early life stages, or more mature pared to the MATC of 63.5 µg/liter,this suggests individuals. an approximate 16 x margin of safety for this single high level; however, this interpretation is ACKNOWLEDGMENTS potentially flawed, being based on 2 different methods of exposure. The minnow larvae were The study as conducted by ABC Laboratories, exposed to concentrations held constant during Inc., was intended to satisfy Good Laboratory the entire exposure time,whereas concentrations Practice regulations and to comply with proto- in the field microcosm study varied temporally. cols, methods, standard operating procedures, Organisms respond to the area under concentra- and sponsor-specified guidelines.The quality as- C tions curve, and discrete samples taken at vari- surance staff of ABC Laboratories was respon- ous times are not necessarily representative of sible for all audits.We thank all of these people actual exposure (Clark et al. 1987, Jarvinen et for the quality of their work and their persistence al. 1988, Parsons and Surgeoner 1991). in the conduct of this study.We also thank Rich- A more suitable approach for risk assessment and Moorman (Zoecon) for his assistance with is to use a measure of central tendency(e.g.,mean, analytical issues, Norma Jean Galiher for her median) for the exposure concentration. The work as study monitor,and Keith Solomon,Uni- mean (S)-methoprene concentrations produced - versity of Guelph,for his constructive review of by each ALTOSID formulation in the micro- the manuscript. ' cosm study,and their associated margins of safe- ty,are shown in Table 4.These margins of safety REFERENCES CITED are quite large,and it is extremely unlikely that any life stage of any fish species would ever be Anonymous. 1983. Proposed new standard practice exposed to levels of methoprene employed in the for conducting fish early life stage toxicity tests.Draft present study during the course of normal mos- No.7,December 1983,ASTM Committee E-47.01. Anonymous. 1989. Water analysis handbook.Hach quito Control operations.' Although the preceding discussion has dealt Chemical Co.,. Loveland,CO. with the direct effects of methoprene on fish,there Clark, cJ. ,J.P.W. re and E.ck,L. R.Goodman,J. M. Patrick,J.C.Moore and E.M.Loren. 1987. Com- are also potential indirect effects. Because this parison of laboratory toxicity test results with re- IGR inhibits insect emergence, it could impact sponses df estuarine animals exposed to fenthion in aquatic insects that are important fish food. the field.Environ.Toxicol.Chem.6:151-160. However,several studies(Miura and Takahashi Dunnett, C. W. 1955. A multiple comparison pro- 1973, 1974; Norland and Mulla 1975) demon- cedure for comparing several treatments with a con- strate that methoprene levels inhibiting nontar- trol.J.Am.Stat.Assoc. 50:1096-1121. get aquatic insect emergence are also substan- Ellgaard, E. G., J. T. Barber, S. C. Tiwari and A. L. tially higher than those used for mosquito control. Friend. 1979. An analysis of the swimming be- Furthermore,the mode of action of methoprene havior offish exposed to the insect growth regulators is not larvicidal—it does not kill and thus remove methoprene and diflubenzuron.Mosq.News 39:311— larval insects from the food chain. Prey organ- 314. isms exposed to methoprene remain in the food Environmental Protection Agency. 1978a. Registra- tion of pesticides in the United States, proposed chain while they continue their growth and de- guidelines.Federal Register 43:29692-29741. velopment. In fact, methoprene exposure fre- Environmental Protection Agency. 1978b. Guide- quently prolongs larval insect development time, lines for deriving water quality criteria for the pro- thus further prolonging prey availability. tection of aquatic life. Federal Register 43:12506, 29018. CONCLUSIONS Jarvinen,A.W.,D.K.Tanner and E.R.Kline. 1988. Toxicity of chlorpyrifos,endrin or fenvalerate to fat- This study demonstrated that under pro- head minnows following episodic or continuous ex- longed, constant-exposure laboratory condi- posure.Ecotoxicol. Environ.Safety 15:78-95. tions,methoprene concentrations of 84-160 µg/ Madder,D.J.and W.L.Lockhart. 1978. A prelim- had adverse effects on the growth of fathead inary study of the effects of diflubenzuron and meth- literorrene on rainbow trout(Salmo gairdneri Richard- minnow fry. Although these concentrations ap- son). Bull.Environ.Contain.Toxicol. 20:66-70. pear to be rather low, they are 196-466 times McClave,J.T.,J.H.Sullivan and J.G.Pearson. 1981. higher than average levels of methoprene present Statistical analysis of fish chronic toxicity data. In: when formulations containing this IGR are ap- Aquatic toxicology and hazard assessment: fourth plied for mosquito control(Table 4 and Ross et conference. ASTM STP 737. American Society for al. [19941). Therefore,we conclude that metho- Testing and Materials. prene, applied as any existing ALTOSID for- McKague,A.B.and R.B.Pridmore. 1978. Toxicity mulation,does not present an unacceptable risk of Altosid and Dimilin to juvenile rainbow trout and /JUNE 1994 METHOPRENE/FATHEAD MINNOW EARLY LIFE STAGE STUDY 22 coho salmon. Bull. Environ. Contam. Toxicol. 20: Bergot,B. H. Sleight and K.J. Macek. 1976. En- 167-169. vironmental degradation of the insect growth regu- Miura,T.and R.M.Takahashi. 1973. Insect devel- lator methoprene. IX. Metabolism by bluegill sun- opment inhibitors. 3. Effects on nontarget aquatic fish.Pestic. Biochem. Physiol. 6:523-529. organisms.J. Econ.Entomol.66:917-922. Ross, D. H., D. Judy, B. Jacobson and R. Howell. Miura,T.and R.M.Takahashi. 1974. Insect devel- 1994. Methoprene concentrations in freshwater mi- opment inhibitors. Effects of candidate mosquito crocosms treated with sustained-release ALTOSID® control agents on nontarget aquatic organisms. En- formulations.J.Am.Mosq.Control Assoc. 10:202— viron.Entomol. 3:631-636. 210. Mount, D. I. 1968. Chronic toxicity of copper to Siddall,J. B. 1976. Insect growth regulators and in- fathead minnows (Pimephales promelas Rafin- sect control:a critical appraisal.Environ.Health Per- esque).Water Res. 2:215-223. spect. 14:119-126. Mount,D. I.and W. A. Brungs. 1967. A simplified Sokal, R. R. and F.J. Rohlf. I973. Introduction to dosing apparatus for fish toxicology studies. Water biostatistics.W.H.Freeman and Co.,San Francisco, Res. 1:21-29, CA. , Norland, R. L. and M. S. Mulla. 1975. Impact of Tietze,N.S.,P.G.Hester,J.C.Dukes,C.F.Hallmon, Altosid on selected members of an aquatic ecosys- M.A.Olson and K.R.Shaffer. 1992. Acute toxicity tem.Environ.Entomol.4:145-152. of mosquitocidal compounds to the inland silverside Parsons,J.T. and G. A. Surgeoner. 1991. Effect of Menidia beryllina.J.Fla.Mosq.Control Assoc.63: exposure time on the acute toxicities of permethrin, 1-6. fenitrothion, carbaryl and carbofuran to mosquito U.S. Congress. 1979. Toxic substances control act. larvae. Environ.Toxicol.Chem. 10:1219-1227. Public Law 94-469.Federal Register 44:16291. Quistad, G. B., D. A. Schooley, L. E. Staiger, B. J. WHITWORTH PEST CONTROL INC. 3707 - 96th STREET E. TACOMA, WASHINGTON 98446 (206) 535-1818 November 9, 1990 o I ' Ron Straka Renton Parks Department JUN 151995 200 Mill Avenue South Renton, WA 98055 CITY OF RENTON Dear Ron, Engineering Dept. T have examined and cataloged all light trap specimens and have prepared a separate report to satisfy DOE ' s requirements. I was very unhappy with our light-trapping program and think it needs major revisions for next year. Specimens were in very poor condition. making it difficult to identify to genus, let alone species. It appears they were handled after they had become dry and brittle and many appendages were broken. Numbers of mosquitoes and all other insects were low in all samples, making me wonder if the traps were operating properly. In previous years, collections from the same sites produced many more specimens. For next year I would recommend the following changes : 1 . Move at least one trap to a location on the edge of or within the swamp. The Bresen trap on South 9th would be the best to move . I know of several better locations. 2 . Turn over light trap sampling responsibility to my firm or have me give your employee detailed instruction on handling of specimens and light trap operation. 3. Traps need to be checked regularly to be sure they are functioning properly and come on during critical hours. I was surprised to see the low numbers of _Cogiulletidia in light trap samples. Cuiiseta and Culex occurred at much higher levels than in previous years. This may effect our choice of chemicals in the future . However, it may just reflect problems with sampling. Sincerely. cow i [t�Y/ ^b� nK / Terry Whitworth. PhD k+ Entomologist �(Scur�Q of kA_4— �e� WHITWORTH PEST CONTROL. INC. 3707 - 96th STREET E. TACOMA, WASHINGTON 98446 (206) 535-1818 Annual Mosquito Abatement Monitoring Report for 1990 November 9 , 1990 Ron Straka Renton Parks Department 200 Mill Avenue South Renton , WA 98055 Dear Ron, The following is a review of the data gathered on mosquito populations from 6/8/90 to 9/28/90 in residential areas above the Panther Creek Marsh. The enclosed table is based on light trap collections at two sites. the Ermo residence at 223 South 19th and the Bresen residence at 901 South 9th Street. Traps were set on timers so lights were turned on from about 8pm to Gam each day. Samples were collected weekly. In addition to light-trapping. the swamp was inspected regularly on the following dates, 5/21 . 6/1 , 6/15 , 6/22 , 6/29 , 7/10, 7/13, 7/16 . 8/10, 8/24 , and 9/4/90. After the 7/16 Altosid XR treatment, few mosquitoes were seen in the swamp and no more homeowner complaints were received. After the treatment I saw no evidence of any impact on non-target organisms. No dead animals were observed and many midges and other aquatic invertebrates were seen after the treatment. Chemicals used for treatment were 18% Scourge (SBP 1382 , Resmethrin) , diluted to 9. 5 oz . per gallon and Altosid XR ( 1 . 8% Methoprene ) . The following is a list of treatment dates , sites, chemicals and quantities used: 6/29/90 upland areas, well away from swamp. 7 gallons Scourge 7/10/90 upland areas, 6 gallons Scourge 7/ 13/90 upland areas. 5 gallons Scourge 7/16/90 10 cases Altosid ( 220 briquets per case ) , 4 gallons Scourge Altosid XR application rates were 1 briquet per 100 square feet per foot of depth. Scourge rates were 2 - 2 . 5 oz. of 18% Scourge per acre. If you need further information, feel free to contact me . Sincerely, c Terry Whitworth, PhD Entomologist Female Mosquitoes Collected Between 6/8/90 - 9/28/90 by Light Trap Ermo 6/8/90 8 Coauilletidia perturbans 3 Culiseta sp. Bresen 6/8/90 2 C, perturbans Ermo 6/15/90 3 C. perturbans 1 Culiseta sp. 1 Culex sp. Bresen 6/15/90 None (light bulb out ) Ermo 6/22/90 3 C. perturbans 2 Culex sp. Bresen 6/22/90 None ( light bulb out ) Ermo 6/29/90 1 Culiseta_ sp. 3 Culex sp. Bresen 6/29/90 2 Culiseta sp. Ermo 7/6/90 1 C. perturbans 3 Culiseta sp. Bresen 7/6/90 None Ermo 7/13/90 12 C. perturbans 4 Culiseta sp. 4 Culex sp. Bresen 7/13/90 1 C. perturbans Treated July 16 . 1990 with Altosid XR Ermo 7/20/90 2 C. perturbans 5 Culex sp. Bresen 7/2.0/90 1 C. Perturbans Ermo 7/28/90 3 Culiseta sp. 2 Culex sp. Bresen 7/28/90 None Ermo 8/3/90 1 C. perturbans 2 Culiseta sp. 1 Culex sp. Bresen 8/3/90 None Ermo 8/10/90 2 Culex sp. 1 Culiseta sp. Bresen 8/10/90 3 Culex sp. Ermo 8/17/90 1 C. perturbans Bresen 8/17/90 1 Culiseta sp. Ermo 8/23/90 3 Culiseta sp. 1 Culex sp. Bresen 8/23/90 None Ermo 9/4/90 2 Culex sp. 3 Culiseta sp. Bresen 9/4/90 2 Culiseta sp. Ermo 9/14/90 1 Culex sp. Bresen, 9/14/90 1 Culiseta sp. Ermo 9/28/90 None Bresen 9/28/90 None WHITWORTH PEST CONTROL 15001 - 25th Ave.Ct. L 1 8 July, Tacoma,Washington 98445 535-1818 or 531-7925 .'nnald r:;. I.eirct t,arks t'uperi.ntendent Municipal Building 200 Mill Avenue South ltcnton, '1a. 98055 I!ear Ron I I hevo identified the mosquitoes you've collected so far„ an well a.s those I got at Philip fmold Pprk Thiglsdn.y nif*ht (July l(rth). I've included n licit of Identifications for your reference. I :Cotaid. .three goneres Codauillettidia.g Cull.-atq, anal 'ulex. A discussion of each follows. Qpguillettidia 1lretuxbans, — This is a new freneric clecilrnstion and wan formally known as Mansonia rA oturbans. `.Oils ist by fnrp the most common species observed in the problem areas. It Is concid-ored a severe biter and will travel great d1stancos. 2'lae larval_ Aaf- ovrrwinters in the mud. Me larvae have the unusual habit of attaching to the stems rind roots of a.qumti_c plaits rat}ier than f'loatitir; at the surface. Ibis makes sampli.nrr, of larvae very difficult, if not impossible. It seems very likely that the Panther Creek E4arsh is a very important r..ource of this m,ecies. This genus is poorly known and very little information In availal-Ac on its control. I will attempt to gather more infom. ation bofore makbig control recommendations. Culrota incideno and Culiaeta inornata wore both collected. but the former species appears most common. `,oro specimenn were damaged and could only be identified to genus. Culiseta incidcns hacl spotted wings and breeds year around in ll sorts of permnnont pools„ This species In a common pest of men; the larval stage overwinterc. Culiaota inornata is primarily a peat of largo domestic animals such as horees and cattle and also broods in permanent pools. ff 1. 0 l WHITWORTH PEST CONTROL 15001 -25th Ave Ct. E. Tacoma,Washington 98445 535-1818 or 531-7925 Culox taraa l s - -Found only at two cites, Utility R/W j�39 and the Reevols property. It broods almost anywhere, especially i.n di-tches and potholes. It oen be an important vector of cmeephalitis. Adult females overwintor in protected areas such as rock. piles. Bacod on the da-ba Y have todato, only Coguuwcttidla o�rbana i.s uresent in cufsieiont numbers to be a nerious pnE;t. 'Ikuat- moot of the Fraither Creek 'Marsh w:i'h Dursban 2 G should re(luce post nimbors considerably in tho rosidcriti,il area^. July, Aug-u,ty and ^�ptomber are likely to be the peak problem rnonthm. -inceroly, Terry L. 'W'hi tworth, Pli. D. 111t.0M01.0 cl s. Pnclocuro r i WHITWORTH PEST CONTROL 15001 -25th Ave. Ct. E. Tacoma, Washington 98445 535-1818 Mosquitoes Collected Ttetween or 531-7925 May 26V 1981 — July 16g 1981 Irmo 5/26/81 1 C ioeta species one specimens legs missing E'rmo 6/2181 1 CUlj00t4 up* one specimen,, head missing Ex"o 6/26/81 6/29/81 11 Coauil.lettldia Perturbane 1 CU11eeta sp• Emo 6/30/81 .• 7/9/81 34 o lettidin porturbans 1 Cull op. Roevols prop. — CtateR/W V2/81 1 Culex tAtsalla Utility n/w ;`4i 7/2/81 2 Conu4Wettidia nerturbans Philip Arnold 7/16/81 5 QWAv2t4 jaoidMa Collected biting between 9s20 p.m. - 10s00 p.m. 22 Coa-uWett1die, perturbane Recvots property 7/15/81 1 Coautllettidia berturbans Philip Arnold Park 7/15/81 3 of ,.lut lettI poxturb a 2 CulipeU inc„�,i ens Victoria Park 7/15/81 2 Coquillettidia perturbans Irmo 7/15/81 14 C,o-Q,uQQtt1A1a getr,wrLMMa utility rVir f 39 7/15/81 5 Culex taraalls All specioo collected by New Jersy Light Trap unless otherwise indicated. Moaquitoe numbers represent numbers pinned and idmtifiedm not total collected. Some specimens wore In poor condition and could not be identified. Samples from the Into property contained many specimens# not all were pinned, although total numbers of mosquitoes in each sample have been recorded. i lSl r - September 28, 1981 WHITWORTH PEST CONTROL Mr, Ronald E. Heiret 15001 - 25th Ave. Ct, E. Parks Superintendent Tacoma,Washington 98445 Municipal Building 535-1818 200 Mill Avenue South or 531-7925 Rentonp Wa. 98055 Dear Ron, The following is an update of species identifications for all light trap collected specimens you've provided me to—date. LOCATION DATE . Ermo 7/16/81 — 7/21/81 46 Coauillettidia perturbans Victoria Park 7/16/81 — 7/21/81 46 .Ci pe�xturbans 1 Cul„�iseta species Reeve's property 7/22/81 1 Cul seta sp. Reeve's property 7/29/81 1 C, pLerEtkurbanp Tully Hills 7/14/81 470 ,C,a perturbans 5 Cul�iseta sp. Tully Hills 7/20/81 — 7/28/81 75 ,CCL perturbans Utility R/W 7/22/81 7 ,C,& perturbans Utility R/W 7/29/81 6 CA perturbans Victoria Park 8/12/81 150 C._& perturbans Victoria Park 8/25/81 30 C,L perturbans Ermo 7/20/81 — 7/28/81 50 C. nerturban,e Er°O 8 1 81 / 100 C. perturbans Sincerely,, Z, Terry L. %itworth Ph D Entomologist �t Si• 6 TLW:ac Neighborhood Detail MA /Site .-Ma 15 1t Tj&th [t. SW 16th S -- P ojeC i tS -- LSW 1 th St 167 S 19th a N 21 st St t Q � � � I � Y J SW 23 S 23rd S t > Q -- W 27th St SW 27 St 3 SW 2 th S ----�---- SW Oth St - J _ � - a �' SW 34th St SW 4th t 0 17�nd St Y -- 0 0 SW 39th St SW 41st St. SW 41st St­ri NOTE: TREATMENT WILL NOT BE APPLIED TO WATER OR WETLAND AREAS . 0 1000 2000 1 : 12000 1 ' I — 405 LdC(a � � N W Y 5 S.w. tfth sT. FULL TREATMENT AREA - UPLAND, Y TEMPORARY TREATMENT AREA I — _��� S 23rd ST r r o w cc > O — N W ~ S.wo 27th ST._.__J S.W. 3Ath � n _M N S th CRY Or RCNTON MOSQUITO ABATEMENT HOSPITAL �~