The Susceptibility and Behavioral Response of Anopheles Albimanus Weidemann and Anopheles Vestitipennis Dyar and Knab (Diptera: Culicidae) to Insecticides in Northern Belize, Central America
Uniformed Services University Of The Health Sciences Bethesda United States
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During a 9-month study period 1995-1996 in Caledonia Village, northern Belize, anopheline mosquitoes collected off human-bait and from experimental huts were evaluated for their susceptibility and behavioral responses to DDT and deltamethrin. Adult Anopheles albimanus, Anopheles vestitipennis, and Anopheles crucians were completely susceptible at diagnostic dosages for DDT 4.0 and deltamethrin 0.025 using the standard WHO susceptibility testing method. Dose response probit analysis indicated low heterogeneity for all 3 species populations response to DDT and deltamethrin. Behavioral responses were measured using excito-repellency ER boxes allowing either direct contact irritancy or noncontaet repellency to be observed. Use of ER boxes produced strong behavioral avoidance responses with DDT and deltamethrin contact irritancy tests during 60-min exposure for An. albimanus and An. vestitipennis compared to controls and noncontact trials. A significant repellency response was noted for both species during the 5-hr noncontact tests compared to controls. The behavioral effect of insecticides on mosquitoes has frequently been overlooked as an important means of reducing human-vector contact. This investigation supports the importance of avoidance behavior excito-repellency, in particular with DDT, as effective suppressive components in defense against malaria. These results indicate that the continued use ofindoor residual insecticide spraying still bears merit as a means of decreasing transmission of maIaria in northern Belize.