Microbial growth enhances the attractiveness of human sweat for the malaria mosquito, Anopheles gambiae sensu stricto (Diptera : Culicidae)

Behavioural responses of the malaria mosquito Anopheles gambiae s.s. to vol atiles emitted by pooled and individual sweat samples collected from human volunteers were quantified in a dual-port olfactometer. Both fresh and incu bated sweat samples were attractive to An. gambiae, but incubated sweat was selected significantly more when the sweat samples were tested against eac h other. The enhancement of the attractiveness of the sweat following incub ation at 37 degreesC appeared to be due to volatiles resulting from bacteri al growth during incubation. The pH value of a sweat sample did not affect behavioural responses to sweat. The role of specific bacterial groups and s ubstrates in odour-mediated host-seeking behaviour is discussed.