The response of Anopheles gambiae s.l. and A. funestus (Diptera: Culicidae) to tents baited with human odour or carbon dioxide in Tanzania

Abstract

AbstractField studies on the response of Anopheles gambiae s.l. Giles and Anopheles funestus Giles to tents baited with human odour or carbon dioxide were conducted in south-east Tanzania. Two exit traps and a CDC miniature light trap set beside a bed net were used to sample mosquitoes that entered the tent. Human odour, pumped from an underground pit into a bed net attracted a similar number of mosquitoes as a bed net occupied by a human male. Significantly fewer mosquitoes were caught in a tent into which carbon dioxide (300 ml min-1) was pumped than in a human-odour baited tent (9 and 27% for A. gambiae s.l. and A. funestus respectively). A five-fold increase of the carbon dioxide concentration (to 1500 ml min-1) did not increase the catches of A. gambiae s.l. whereas those of A. funestus were increased to 69% of the catches by human odour. Species identifications of A. gambiae s.l. catches showed that A. arabiensis Patton prevailed and that the proportions of A. arabiensis/A. gambiae s.s. did not differ between treatments. It is concluded that in the indoor situation described, human odour other than carbon dioxide is the principal cue to which these malaria vectors are attracted and that the physical presence of a host and carbon dioxide, when used as a kairomone on its own, accounts for only a minor part of the overall attractiveness of man, particularly for A. gambiae s.l.