The dispersal and survival of Anopheles Culicifacies Giles (Diptera: Culicidae) in a Sri Lankan village under malathion spraying

Abstract

AbstractTwo mark-release-recapture experiments with Anopheles culicifacies Giles were carried out immediately before and one month after a round of malathion spraying of houses (at 2 g/m2) in a village in north-western Sri Lanka. In the first experiment the measurement of bidirectional movement of females collected in two halves of the village showed that movement was somewhat affected by wind direction; the percentage of migrants moving partially upwind was greater (11·4) than that in the reverse direction (6·4). The best estimates of daily survival were 0·79 before spraying and 0·44 after spraying; population sizes were about 44 500 and 1300, respectively. The proportion of females resting in the collection huts rose after spraying. The results are discussed with reference to the evolution of insecticide resistance in populations under insecticidal pressure and those populations not selected by spraying.