Journal of the American Control Association, ll(2):230-234, lgg5 Copyright @ 1995 by the American Mosquito Control Association, Inc. OPERATIONAL AND SCIENTIFIC NOTES

AEDES ALBOPTCTU,SAND OTHER AEDES FTEGOMYIA) SPECIESIN

B. H. KAY,' G. PRAKASH2 erp R. G. ANDRE3

ABSTRACT. During an assessmentof the dengue situation in Fiji in early 1992, a house-to-house survey of container-breeding Aedes was made. Discarded tires and water drums were identified as key breeding sites for the 4 potential dengue vectors: , , Aedespseudoscutellarii, and . Aedes albopictrrs were detected on Viti Levu, Vanua Levu, and on Taveuni. Examination of early records and of used tire importation suggestsentry into Fiji after July 1985 but well beforeJuly I 988 when the specieswas first detected.It is alsopossible thel e. albopictuswasintroduced via aircraft from Hawaii. In Suva, the 4 Stegomylrrespecies coexist, but in I_autoka, it appears that Ae. albopictus may be displacing Ae. pseudoscutellaris.

The expansion of Aedesalbopictus (Skuse)in Nausori. During February 1992, while on a the Western Pacific region was first noted for USAID funded mission (Andre et al. 1992a)on northern New Guinea in 1972(Schoenig 1972) the surveillance and control of dengue and its and the Solomon and SantaCruz islands by 1978 vectors,we extendedthese findings by surveying (Elliott 1980). Following surveysin 1992, Ae. 3 of the major islands,Viti Levu (7 sites),Vanua albopictuswasalso detectedin the port ofKiunga kvu (6 sites), and Taveuni (9 sites). Both wet and on Daru Island in the Western Province of and dry containers were recorded and any im- New Guinea (regularly linked by sea or air re- maturestherein collectedwith a l0 x 20-cm net spectively to northern Australia) (Cooper et al. (Tun-Lin et al. 1994), counted, and aliquots 1994).In 1988 and 1989, respectively,Ae. al- identified. This enabledus to examine the prev- bopictus was intercepted in Brisbane and Dar- alenceof Aedes(Stegomyia) spp. in key centers win, Australia (Kay et al. 1990),and in 1993in in Fiji and to estimate the relative importance Auckland, New Zealand (Laird et al. 1994). of each container type in terms of the numbers The Fiji Islands are located in the southwest of immatures being produced. On this basis, we PacificOcean approximately 3,000 km northeast then were able to recommend some prioritiza- of Sydney,Australia. One-third ofthe more than tion of the limited resourcesfor vector control. 300 islands of Fiji are inhabited, but most of the The following localities were surveyed:Burata population lives on the 3 largest islands: Viti St. settlement, Nanuka St. settlement, Nadera, Levu, Vanua kvu, and Taveuni. Suva is the Suvaport, Samabulaand Edinburgh Drive (Suva largestcity, main port, and capital. Travel among area), Nagali village (Nausori area), all on Viti these islands the capital is frequent and rapid, [rwu; Nagigi village, Vaivita and St. BedesCol- facilitating movement of humans and perhaps lege,Savarekareka (all grouped as rural in Table mosquitoes infected with dengue or other ar- 1), I-abasa,and Savu Savu, all on Vanua kvu; boviruses. The most recent outbreak of dengue Somo Somo, Lamini and Lovonivonu villages, hemorrhagic fever occurred in 1989-90 with Government Station. Baculevu Government more than 3,600 confirmed casesand 30 deaths School, Vuniuto settlement and 3 resorts, Gar- (Ministry of Health, Suva, unpublished data). den Island, Bibi's Hideaway, and Matei Lagoon, In Fiji, Laille et al. (1990) detectedAe. albo- all on Taveuni. pictus in ovitraps, a mango tree hole, and in a A total of 1,37I containerswas inspectedfrom tire in the Nadi areabut not in Suvaor its airport, 198 premises(Table l) and 132 of them were found positive for Ae. (Stegomyia) species.Dis- carded tires comprised 16.40/oof containers in- spectedbut of these47o/o were wet and over half 1 Mosquito Control Laboratory, Insti- Queensland (53olo) positive for larvae. Allowing tute of Medical Research,P. O. Royal Brisbane Hos- of thesewere pital, Brisbane 4029 Australia. for mixed infestations, the following were iden- 2 National Vector Control Unit, Ministry of Health, P. O. Box 30, Suva, Fijian Islands. 3 Formerly with the Henry M. Jackson Foundation a Andre, R. G., B. H. Kay, E. Kikau and S. H. Wa- and the Vector Biology and Control Project; now with terman. 1992. Assessmentof the epidemiology of the Department of Preventive Medicine/Biometrics, dengue and its past, present and future control in Fiji. Uniformed ServicesUniversitv ofthe Health Sciences. Vector Biology and Control Project Report no. 8 I 269. Bethesda.MD 20814. Arlington, VA.

230 JtrNr 1995 Opnr,qrrorer-,cNo ScteNTIRcNorEs 231 tified from tires: Aedes aegypti (Linn.) (39), Ae. Government Station), suggestingthat it is well albopictus (28), Aedes pseudoscutellans(Theo- established. Although introduction of exotic bald) (4), Aedespolynesrensls Marks (l), Culex mosquitoes is well documented throughout the quinquefascialzs Say (4), Culex annulirostris Pacific region (Pillai and Ramalingan 1985), it Skuse(1), and Toxorhynchitessplendens (Wied.) is interesting to speculateon how and where this (l). There were 10,667 Aedes (Stegomyia) im- specieswas introduced and its consequence. matures in 68 tires counted (mean 157, range 3- Fortunately, the National Vector Control Unit 596), which comprised 65.20/oof all Stegomyia has records of house-to-housesurveillance for collected. 1981and for 1982and from 1988to l99l for Drums comprised 4.2Voof containers exam- Suva and Lautoka. Isolated records indicate Ae. ined and 630/oof these contained water. More albopictus was already well established in the than 610/oof wet drums were positive, mainly for westerndivision around Ba (Tavua rural) and at Ae. aegypti but also infrequently for Ae. albopic- Sigatokatown and rural areasby October 1988. tus, Ae. pseudoscutellarus,and Ae. polynesiensis. It was common in Lautoka in November 1988 Some 3.624 immatures were collected from 22 and in industrial, residential, and outlying rural positive drums (mean 164.7, range 3-909) and areas of Suva in 1989. Its widespread distribu- this comprised22.lo/oof the total immatures col- tion throughout Viti kvu by 1989 suggestsin- lected. troduction somewhat earlier than its initial dis- In contrast, tins and bottles were numerous, covery in July 1988. comprising 48o/oof total containers examined. Analysis of the relative proportions of Ae. ae- Although 40. l0loof these contained water, only gypti:Ae. albopictus in tires for both Suva and 5.70loof these were positive. Overall, their con- Lautoka for each year between 1989 and l99l tribution to total Aedes(Stegomyia) collected was (Table 2 gives totals only) indicated no signifi- 2.30/0,with these containers averaging 28.2 (l- cant differencesfor locality (F : 3.74,df : 1,4, 66) immatures. Becausemany bottles in partic- P:0.13) and foryearsfor Suva(12: 2.88,P ular were exposedto full sunlight, by mid-after- :0.24) and Lautoka(x2: O.04,P:0.98 and noon the glassand contents often becamewarm. for 1988-91,X2 : 0.27,P: 0.98),perhaps in- This was thought to be a factor mitigating col- dicating some degreeof equilibrium and/or sta- onization. All 4 speciesof Aedeswere found in bility. bottles and tins. One possible source, used vehicle tires were Of the other biotopes, Ae. albopictuswas also first imported into Suva from Asia in July 1985 found in plant pot bases,shells, iron parts, a tree and currently at least 8 importers operate through hole, and in a Pandanusaxil with Aedesfijiensis this port. There are no official records of such Marks. The biotopes occupied by these Aedes importations but by far the greatestvolume is spp. are well known, as are the susceptibilities landed at Suva docks. Between July 1985 and of Ae. polynesiensis, Ae. pseudoscutellarrJ, and 1988, 2 smaller importers commenced opera- Ae. fijiensis to Wuchereria bancrofti (ke et al. tions through the secondaryports ofNadi and 1982, 1987). Lautoka. Tires landed at Suva currently are re- With respect to transmission of dengue, this distributed to 12 businessesthroughout the Fi- study clearly indicates that discarded tires and jian islands, principally wia the ferry service linked 200-liter drums should receivepriority attention to Suva but not to Nadi. Tires are mainly redis- in view of their relative contribution to the total tributed prior to any retreadingprocess, thus en- numbers of immatures collected. Collectively, suring rapid potential transfer of Ae. albopictus therefore, 82.7, 99.7, and 99. I o/oof Ste go myia at within the casings.It is thought that most ofthese the key population centersofSuva, Labasa,and imports are from Japan and therefore would in- Savu Savu were being produced by 36.3, 47.1, volve a cold-hardy strain. The other option is and2o.4o/oof potential breeding sites inspected. associatedwith the possible breakdown of dis- In rural Vanua Levu and on Taveuni, tires and insection procedures,following the military coup drums comprised 10.6 and 6.90/oof inspected of 1987,at Nadi airport, which is well connected containers and produced, 42.8 and, 37.5oh, re- with direct flights from Hawaii. A tropical strain spectively, of total Stegomyia found. Focusing of Ae. albopiclzsis well establishedthere. During on the principle of key containers (Tun-Lin et our 1992 survey, there did not seemto be clear al., in press)would ensurethat limited personnel responsibility and adequateliaison between those could be usedmost cost effectivelyto reduce,4e- concerned with agricultural and medical quar- des numbers. antine duties. Aedes albopicttr.r was found on all 3 islands The prognosis (Table 2), based only on local surveyed,that is, Viti Levu (Suva, Nadera, Na- authority surveillancedata, suggeststhat the wet- nuka St. settlement),Vanua Lavu (Labasa,Nai- ter capital of Suva (3,841 mm rainfall annually) gigi), and Taveuni (Somo Somo, Lovonivonu, will b€ at risk of dengue transmission by all 4 232 JounNer or rns ANtrnrcAN Mosqurro Covrnol Assocrnrror.r Vou I l, No. 2

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Table 2. Summarized Aedes(Stegomyia) suweillance data for l98l-82 and 1988-91, Suva and Lautoka, Fiji Islands. Number of positive containers detected wfi}r Aedes pseudo' albo- scutel- polyne- Locality Biotope Year aegypti pictus laris siensis Suva Tires l 98l-82 222 068 I l 989-9 l 165 97390 Drums l 98l-82 44 0170 l 989-9I l7 ll 8 0 Plant containers l 98r-82 89 0960 r989-91 2l 39270 Tins, bottles, shells I 98l-82 79 0782 l 989-9 l t2 13130 I-autoka Tires r982 45 0190 l 989-9 I ll6 l0l 00 Plant containers r982 t4 o240 I 989-9 l 22 35l0

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main islandof PapuaNew Guinea.Philipp. Sci. 9:61- Tun-Lin, W., B. H. Kay and T. R. Burkot. 1994. 82. Quantitative sampling of immature Aedesaegypti rn Tun-Lin, W., B. H. KayandA. Barnes. Understanding metal drums using sweepnet and dipping methods. productivity, a key to Aedes aegypti surveillance. J. Am. Mosq. Control Assoc.10:390-396. Am. J. Trop. Med. Hyg. (in press).