A predevelopment mosquito survey in the Mahaweli Development Project area, Sri Lanka: adults.

Abstract

The adult mosquito fauna of forest land due to be developed into irrigated agriculture under System C of the Mahaweli Development Project of Sri Lanka was surveyed in 1984 and 1985. Seventy-one species of mosquitoes were collected during the survey, 38 of which were taken at diurnal human bait; the most abundant were Aedes albopictus (Skuse), a vector of dengue in Southeast Asia, Ae. novalbopictus Barraud, and Ae. w-albus (Theobald). Nocturnal human-bait catches yielded 48 species, of which Mansonia annulifera (Theobald), was dominant. Other common species included Culex tritaeniorhynchus Giles, Cx. gelidus Theobald, Cx. fuscocephala Theobald, and Cx. pseudovishnui Colless, all potential vectors of Japanese encephalitis, and Anopheles culicifacies Giles, the established vector of human malaria in Sri Lanka. CDC light traps attracted 49 species, of which the most abundant were Mimomyia hybrida (Leicester) and Cx. pseudovishnui. Thirty-two species were collected from temporary huts in the forest; Ma. annulifera was dominant. Significant seasonal and site-related density differences were apparent in several species. There was evidence of the rapid invasion of areas disturbed by humans by two peridomestic species, Culex quinquefasciatus Say, the vector of bancroftian filariasis in Sri Lanka, and Armigeres subalbatus (Coquillett). Considering the likelihood that environmental changes associated with development will lead to increased population densities of at least some of these potential vectors, mosquito-borne diseases can be expected to play a significant role in human health after settlement and irrigation.