JouRNlr, oF THE AnapnrclN Mosquno Contnor, Assocrertorl V o L . 4 , N o . 3

OPERATIONAL AND SCIENTIFIC NOTES

ByRoNrpxAqer.oil;;ff -1"ff':j-fi::"':J:"".Hi"oMASMLoyLEss,'JOHN A. MULRENNEN, JR.,' PAUL R. SIMMONDS,' INONINO PADGEIT, JR,'-__-'EVELYN K. COOKg eno THOMAS R. EDDINS3

Used tires are an important man-made sourcefor mosquito proliferation and dispersal (prattet al. 1946, Craven et al. 1988). R-capping hasmade them a valuable commodity; thus, inter-national and interstate movement is common(Reiter and Sprenger 198?). This is importantwhen it involves mosquitoes incriminated asdisease vectors. Such is the case with Aed.esalbopictus (Skuse) which has recently been dis-covered in 17 of the continental United States[Centers for Disease Control (CDC) 1982]. Un-der suitable conditions, this mosquito is an im-portant vector ofdengue viruses (Shroyer 19g6).In addition, it is an aggressive human-biter caus-ing considerable discomfort.

The purpose of this report is to document thediscovery of Ae. ahopictus in Florida and toelaborate on implications, preliminary surveil-lance observations, and control efforts and ob-stacles.

Aedes ahopicfus, known commonly in the U.S.as the "Asian tiger mosquito," first was discov-ered in Florida on July 3, 1986 in Jacksonville(Duval County), located in the northeast portionof the state (30" 20'N). Biting females werecollected from a large tire lot 3.b km west ofthedowntown area (Fig. 1) during an intensive sur-veillance effort organized in response to its dis-covery in other southern states. Aedes ahopictusfemales were aspirated during biting collectionsin very Iow proportions (ca. 1:100) compared toAedes aegypti (Linn.).

A subsequent survey of Duval County in Au-gust 1986, including 3 seaport facilities andabout 60 tire dumps, revealed that the infesta-tion was limited to this large tire lot and an

I Mosquito Control Branch, Jacksonville Bio-En-vironmental Services, 1321 Eastport Road, Jackson-ville, FL 32218.

2 Entomology Services, Florida Department ofHealth and Rehabilitative Services, P. O. Box 210.Jacksonville, FL 32231.

3 Escambia County Mosquito Control, 603 WestRamona St., Pensacola, FL 32501.

a Current Address: Environmental Sewices, Inc.,9471 Baymeadows Road, Suite 408, Jacksonville, FL322L6.

5 Current Address: Department of Biology, GeorgiaSouthern CoIIege, Statesboro, GA 30460.

adjacent property containing scrap tires. Thetire lot had been in operation for only 1gmonths, during which time, between 1 and 2million unsalvageable, used tires had been stock-piled for eventual shredding for fuel. Truck andautomobile tires were stacked 2-B m high over/ na.

Aedes albopictur was found breeding through-out the tire Iot with the greatest concentrationof larvae occurring in shaded tires next to aheavily wooded ravine. Relatively high landingrates of several dozen/minute were experiencedduring each visit to the ravine during the hottestperiods of the day. Aed.es albopirtrzs had dis-persed from this point 2 km to the south andeast along an adjoining creek. Within this area,we located 5 used-tire dealers, B truck-tire re-cappers, 2 smaller tire dumps and one used-tirewarehouse. Breeding was found in tires outsidethe warehouse, behind one of the recappers andin junkyards aligning an adjacent highway. Lar-vae were collected from a variety of discardedcontainers, such as bottles, jars, cans, hubcaps,toilets, sinks and 5-gallon buckets. Most larvaewere collected from used tires. None were col-Iected from tree holes.

Further investigation revealed that during thepast 5 years, a prosperous business involvingimporting, recapping and reselling Japanesetruck tire casings had developed. From 120 to144 containers of tire casings, holding about 800tires per container, were imported to Jackson-ville annually. An average of t-2% of these tireswere unusable and disposed as scrap (WayneJohnson, Retread Corporation of Florida, per-sonal communication). At this rate we estimatedbetween 360-830 foreigrr scrap tires were addedto the stockpile at the infested tire lot each year.Efforts to inspect tire shipments at random forthe presence of mosquitoes were negative.

Several surveillance techniques were em-ployed to estimate the distribution, prevalenceand population density of. Ae. albopir.tus in theinfested area. Weekly, one-minute landing ratecounts, battery-powered aspirator and sweep netcollections (Kumm and Novis 1938. Ho et al.1971) were made between 0900 and 0930 hr fromJuly 8 to September 30, 1986. During the initialinspection of the downtown tire dump in August,

364 JounNlr, oF THE Arrannrclr.r Mosqumo ConrRol AssocrATroN VoL. 4. No. B

sition traps (Thaggard and Eliason 1969) wereplaced within the infested site and areas to thenorth and south. Each week eggs from thesetraps have been collected, counted and hatchedand the resulting Iarvae identified. To date, theonly Ae. albopictus eggs that have been collectedwere from the original infested tire lot.

In 1987, the CDC organized a follow-up sur-vey. BitingAedes albopictus were collected abun-dantly at 25 additional sites within a 3 km radiusof the originally discovered tire lot. It was alsocollected in 2 isolated sites ca. 9 km northeastof the tire lot near the city zoo.

During May 24, 1988, 10 female and 2 maleAe. albopictus were discovered in a dry ice-baitedCDC light trap in Brownsville located southeastof Pensacola (Escambia County) in the extremewestern portion of the Florida panhandle. Thecollection was incidental in that the trap wasset in response to complaint calls received bythe local mosquito control agency. The trap wasoperated from 1900 to 0700 hr on May 24 and25 in a moderately forested, residential settingclose to a swamp. Aedes albopicfus made up 80%(12/L5) of the first night collection and 2% (2/93) for the second night. No larval breeding ortires were found in a survey of a 3.2 km2 areasurrounding the trap.

Efforts to control Ae. albopicttts in Jackson-ville with insecticides have been unsatisfactory.Temporary abatement using larviciding oil(Florida Mosquito Larvicide), mixtures of. Bacil-lus thuringiensis israelcnsrs (Vectobac@ 12AS)and permethrin (Pramex@), and thermal foggingwith naled (Dibrom@) in diesel fuel have beenemployed. Insecticidal applications were re-quired at Ieast every 3 weeks to achieve adequaterelief. Manpower limitations and costs of up to$2000/treatment (includes equipment, labor andinsecticide) for the 7 ha site made such as ar-rangement undesirable.

Permanently eliminating mosquito produc-tion through proper tire disposal was resorted toas a better solution to the problem. This in-volved enforcement of existing health and fireordinances restricting tire dumps. Such actionbackfrred with some of the Iarger tire-yard op-erators. Faced with exorbitant landfill disposalcosts of $33/ton for whole tires, they chose tomove the illegal tires to neighboring countieswith less stringently enforced regulations. Ef-forts to prevent this were employed to halt thepotential spread of Ae. albopicfus and other tire-breeding mosquitoes. In one episode involvingthe largest tire lot (Fig. 1), the city of Jackson-ville expedited the disposal process by hiring acontractor to eliminate the tires. The city iscurrently seeking remuneration from the tire-yard operator through the assistance ofthe stateattorney. To avoid future dilemmas, the city now

requires tire haulers to be licensed, bonded andto provide reports on the processing of theirtires. The movement of tires at night has beenprohibited. These measures were intended tohelp preclude the build-up of illegal tire lots. Inaddition, the city is seeking authority to assessa vehicle wheel tax to subsidize a local tiredisposal program.

The discovery of Ae. ahopi,crius in Florida rep-resents the southeastern limit of its distributionin the USA. Duval and Escambia counties arethe only locations where Ae. albopictus havebeen reported in the state. This discovery isunique in comparison to the 16 other continentalstates from which it is known, in that Floridaserves as the gateway to the Carribbean islandswhere endemic dengue has reached epidemicproportions. The Jacksonville infestation is lo-cated in the heart of downtown where manyopportunities for rapid, widespread dispersal ex-ist. There are two major railroad switchingyardsnearby, as well as several commercial truck ter-minals. Three interstate highways crisscross theregion, and a large seaport is within 7 km. Thisport exports over 2,000 cargo containers toPuerto Rico each week (Foley 1986). The geo-graphic proximity and close commercial rela-tionship that exists among the islands and theport cities of Florida make the potential spreadof dengue in the USA a threat.

Furthermore, unless efforts are made to con-trol Florida infestations, it is quite conceivablethat this mosquito could disperse to the islandswhere it currently does not exist. The principalvector for dengue in the Caribbean is Aedesaegypti. It is not known what impact this addi-tional vector would have on the epidemiologly ofthe disease.

ACKNOWLEDGMENTS

The authors gratefully acknowledge the sup-port and encouragement of all the staff of Jack-sonville Mosquito Control Branch and Escam-bia County Mosquito Control. W. L. Jakob (Di-vision of Vector-Borne Diseases, CDC)confirmed identifrcations and assisted in an ini-tial 1986 survey. William Hawley, Dawn Wes-son, Charles Pumpuni, Scott Hanson, StefanNawrocki (Vector Biology Laboratory, Depart-ment of Biological Sciences, University of NotreDame) and Robin Taylor (Ohio State Univer-sity) assisted in conducting the 1987 survey or-ganized by the CDC.

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Craven, R. B., D. A. Eliason, D. B. Francy, et al. 1988.

OprRltroxlr, AND ScIENTIFIc NorEs 365SEPTEMBER 1988

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Foley, J. (ed.). 1986. Jacksonville Port Handbook.Hayes Howard Publication, Inc. Jacksonville, Flor-ida, 96 pp.

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Shroyer, D. A. 1986. Aedes albopictus and arboviruses:A concise review of the literature' J. Am. Mosq.Control Assoc. 2:424- 428.

Thaggard, C. W. and D. A. Eliason. 1969. Field eval-uation of components for an Aedes aesypti (L.)

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