CORRELATES OF THE PERIDOMESTIC ABUNDANCE OF LUTZOMYIA-LONGIPALPIS (DIPTERA, PSYCHODIDAE) IN AMAZONIAN BRAZIL

Abundance of the sandfly Lutzomyia longipalpis, the vector of Leishman ia chagasi, was surveyed using CDC light-suction traps in fifteen vill ages and 180 homesteads on Marajo island, Para State, Brazil. Flies we re most abundant in cultivated areas, secondary growth and open woodla nd, away from savanna grassland and forest. Within homesteads, the abu ndance of flies in animal sheds was weakly associated with the number of hosts kept therein, and inversely related to the number elsewhere, both human and animal. Houses harboured more flies if dogs were presen t and if the house had: a roof of thatch rather than of tiles or tin; a thatched roof which had not been treated with insecticide; relativel y more holes in walls and roof. The sex ratio of flies was more male-b iased at higher densities. We weigh the importance of these variables as risk factors for Le.chagasi infection.