Comparative sensitivity of four Anopheles (Diptera: Culicidae) to five repellents.

Five repellents were evaluated against Anopheles albimanus Wiedemann An. freeborni Aitken, An. gambiae Giles, and An. stephensi Liston, using a "free choice," dose-response testing procedure on rabbits. Overall, deet was the most effective repellent based on effective dosages (ED50's and ED95's), except against An. albimanus. An. albimanus was significantly more tolerant to deet compared with dimethyl phthalate or ethyl hexanediol. Permethrin was effective against all four anopheline species at the ED50 levels; however, the ED95 values were higher compared with the other repellents. There were significant differences in sensitivity of some of the four species to all the repellents tested, except dimethyl phthalate and indalone. The variability in the response of these anopheline species to repellents confirm that the extrapolation of repellent data from one anopheline species to another is unreliable and that comprehensive tests are needed for each species.