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