AN ENTOMOLOGICAL SURVEY ON THE MOSQUITOES OF WUVULU ISLAND, PAPUA-NEW GUINEA F. RODIfAIN and P. GAXOTTE* Viral Ecology Unit, Institut Pasteur, 25, rue du Docteur Roux, 75015 - Paris, France. *Service de Medecine Tropicale, Hopital de la Pitie, 75013 - Paris, France. INTRODUCTION MATERIALS AND METHODS An epidemiological survey on arboviruses The culicids were collected at larval and was carried out on Wuvulu Island, in August adult stages. Thus, all detected potential 1975 and 1976. breeding sites have been prospected; some of them were natural (swamp in the center of the Wuvulu (or Matty) Island is located 142 island, tree holes, coconuts, shells), others miles north of Wewak, in the Sepik district of were artificial (drums for water stocking). New Guinea, 260 miles west of Manus Island All adult mosquitoes were caught while biting (Bismarck archipelago) and more than 600 man, generally near the villages or around the miles south of Caroline Island. Thus, it expedition campus. is a very remote, coralline and small size All the collected mosquitoes were brought island (3,700 acres). back to Paris to be identified. The climate is of oceanic type : the average RESULTS temperature is between 70° and 95°F; the trade winds, whose force is always moderate, Six culicid species are present in this collec­ blow north-westward from June to September tion, but, one of them, the identification is and south-eastward from November to doubtfuL So the list of Wuvulu mosquitoes February ; the annual rainfall is between 80 is as follows : and 120 inches quite evenly distributed Aedes (Stegomyia) hebrideus Edwards throughout the year. The vegetation is a Aedes (Finlaya) notoscriptus (Skuse) very dense primary forest, rich in epiphytes, Aedes (Verrallina) lineatus (Taylor) cleared in some places for coconut palm ? Aedes (Lorrainea) dasyorrhus King & plantation. Hoogstraal The islanders (about 500), of Micronesian Culex pipiens fatigans Wi!Fpelfiann origin and culture, are distributed in two Armigeres breinli (Taylotr' villages, Auna (sunrise) and Onne (sunset), Aedes (S.) hebrideus : Numerous larvae and settled on the west coast where they are two pupae collected in tree), holes, coconuts, miles apart. Traditionally, they live from shells; adults biting mati; in the late after­ their fishing and grow taros, coconuts and noon. This species, which belongs to the sweet potatoes. Work on the plantation is scutellaris group of Stegqmyia, develops very done by a small group of Melanesians from often in domestic breeding sites and is the West Sepik district, liv~ng apart from both usually very aggressive for man. It is known villages so they have but few contacts with from New Hebrides where it is very abundant the native popUlation (Gaxotte, 1975). (Rodhain and Fauran, 1975), Solomon Is- Vol. 8 No. 1 March 1977 77 SOUTHEAST ASIAN J. TRap. MED. PUB. HLTH. lands, Santa Cruz and Torres Islands but This species was yet known from Wuvulu Belkin (1965) have yet recorded it in Wuvulu (Belkin, 1965). in 1956. Armigeres breinli : Larvae collected in shells ; The part played by Ae. hebrideus in the adult females caught on man in the whole transmission of the dengue virus, suspected by island. Shells are classical breeding sites for Daggy (1944), seems likely according to the the larvae of this mosquito. This species is observations made in Espiritu Santo Island known to bite man during daytime in the bush (New Hebrides), where, Ae. aegypti being (Belkin, 1962). Its distribution covers New absent, succeSSIve outbreaks are easily Guinea, Bismarck archipelago, Santa Cruz and spread. Solomon Islands. It has no medical signifi­ Aedes (F.) notoscriptus : Larvae and pupae in cance. tree holes and in metallic drum in Onne and Auna. The larval ecology of this Aedes can DISCUSSION be compared to the bionomics of the earlier mosquito. On the other hand, the adults are When, in 1956, David D. Bonnot made a not anthropophilic, and this fact is confirmed very brief survey on Wuvulu Island, four by their absence in our collections. This species have been collected (Belkin, 1965) species is known from a large area in the viz: Aedes notoscriptus, Ae. hebrideus, Culex South Pacific (Austra1.ia, New Zealand, New squamosus and C. pipiensfatigans. Guinea, New Britain, New Ireland, Moluccas, These two Aedes species have so been found Neo-Caledonian archipelago) and reported in again in 1975, with Ae. lineatus probably the collection studied by Belkin (1965). It introduced since this date, and perhaps Ae. probably has no medical significance. dasyorrhus. This survey affirms the absence Aedes (V.) lineatus: Females collected on man of Ae. aegypti actually. As far as Culex is in the whole island at the end of afternoon, in concerned, only C. pipiens fatigans is still rather large numbers. This Aedes, of which present in the island. However, this species the larvae usually breed in pools with abun­ is certainly the first to be exposed to the dant vegetation or in flooded forests (Huang, anticulicid measures which are carried out 1968) seems to be a man-biting mosquito in from time to time. A. breinli lastly, probably all its distribution area, with the largest of introduced, seems to have taken root in those of Verrallina: Solomon Islands; New Wuvulu Island. Britain, New Ireland, Bismarck archipelago, No Anopheles species have ever been New Guinea, Admiralty Islands, Ceram, observed in the island where malaria is pre­ Amboine, Australia and New Hebrides where sent. However, Anopheles larvae are proba­ Rageau and Vervent (1958), then Rodhain bly present in the swampy central area and and Fauran (1975) drew attention to its they could have escaped from the surveys. abundance in forest and its aggressivity for man. Concerning the medical importance of these mosquitoes, only Ae. hebrideus could be Aedes (L.) dasyorrhus : Only one female in an efficient dengue vector. The serological rather bad condition seems to belong to this survey made in the islanders (Micronesian species, which is known in New Guinea and islanders and New-Guinean Melanesian im­ Solomon Islands. ported workers) shows that dengue outbreaks Culex pipiens fatigans : Many larvae collected which spread over South Pacific did not reach in drums in Auna village and one female. Wuvulu Island (Gaxotte et at., 1975). The 78 Vol. 8 No. 1 March 1977 ENTOMOLOGICAL SURVEY ON WUVULU IsLAND, PAPUA-NEW GUINEA virus introduction anyway is~still always tions at Rabaul relating to incidence and possible, like it happened-in "New Britain or in vectors. Tran.s: Roy. Soc. Trop. Med. Sepik district (New Guinea) in 1971-1972. Hyg., 44 : 291. Except for C. p. fatigans, no recorded culicid BELKIN, J.N., (1962). The mosquitoes of the could be an efficient vector of bancroftian South Pacific ( Diptera, Culicidae). Univ. filariasis, the presence of which was shown by Calif. Press, Berkeley, Los Angeles. Backhouse and Heydon (1950). Vol. 2. BELKIN, J.N., (1965). The mosquitoes of the SUMMARY Robinson-Peabody Museum of Salem Expedition to the South-west Pacific, An entomological survey in Wuvulu Island, 1956. Contr. Amer. Entom. Inst., 4 : 11. Papua New Guinea, in August 1975 and 1976 DAGGY, R.H., (1944). Aedes scutellaris shows the presence of six mosquito species : hebrideus Edw. : a probable vector of den­ Aedes (S) hebrideus, Ae. (F.) notoscriptus, gue in the New Hebrides. War Medicine, Ae. (V.) lineatus, ? Ae. (L.) dasyorrhus, Culex Chicago, 5 : 292. pipiens fatigans and Armigeres breinli. The GAXOTTE, P., (1975). Wuvulu Medical medical significance of these mosquitoes -is Report 1974. discussed, with special reference to the pro­ blem of dengue virus transmission. GAXOTTE, P., RODHAIN, F., ARDOIN, P. and HANNOVN, C., (1975). Results of a sero­ epidemiologic survey on arboviruses in a ACKNOWLEDGEMENTS remote island of South-west Pacific (Wuvulu Island, Papua New Guinea). The authors would like to thank Mr. Trop. Geogr. Med., 27 : 405. Anthony Bais, East Sepik District Commis­ sioner and Dr. K. Farrell, East Sepjk District HUANG, Y.M., (1968). Aedes (Verrallina) of Health Officer, Papua-New Guinea, for their the Papuan subregion (Diptera : Culi­ help and Mr. Alain Boutonnier for his techni­ cidae). Pacific Insects Monogr., 17: 1. cal assistance. Special gratitude is extended RAGEAV, J. and VERVENT, G., (1958). Arthro­ to the people of Wuvulu Island and the parti­ podes d'interet medical ou veterinaire cipants and staff of Project Ocean Search aux Nouvelles Hebrides. Doc. Instituf Wuvulu 1975 and 1976. Francais d'Oceanie et ORSTOM, Nou­ mea. 51 pp. REFERENCES RODHAIN, F. and FAURAN, P., (1975). Resul­ tats d'une enquete sur les vecteurs de la BACKHOUSE, T.e. and HEYDON, G.A.M., dengue aux Nouvelles Hebrides. Bull. (1950). Filariasis in Melanesia: Observa­ . Soc. Path. Exot., 68 : 539. Vol. 8 No.1 March 1977 79 .