HOST SELECTION PATTERNS OF ANOPHELES PSEUDOPUNCTIPENNIS UNDER INSECTICIDE SPRAYING SITUATIONS IN SOUTHERN MEXICO

Studies of host selection patterns of Anopheles pseudopunctipennis wer e conducted in villages in foothills near Tapachula, Mexico. Based on 2 years of collections, 53.8 and 86.1% of all engorged females resting inside houses were found to contain human blood. Estimates of weighte d and unweighted human blood indices, including data from outdoor rest ing collections, varied from 29.5 to 54.7%. Humans and dogs were the m ore common blood sources for all An. pseudopunctipennis mosquitoes, ac counting for 96% of blood meals tested. Results of analyses of host pr eference through estimates of forage ratios (FRs) indicated that the l arge numbers of blood meals from humans and dogs were more reflective of host availability than host preference. An FR of less than 1 indica ted that, in terms of host availability, proportionately fewer An. pse udopunctipennis females fed on humans than other large animal hosts. I n contrast, FRs of 15-20 and 5-7 revealed strong selective biases for horses and pigs as sources of blood meals, respectively. The proportio n of outdoor-resting, blood-engorged females containing human blood de clined markedly after houses were sprayed with DDT. This response to h ouse spraying is attributed to an excite-repellency effect of DDT.