THE RESPONSE OF ANOPHELES-GAMBIAE SL AND A-FUNESTUS (DIPTERA, CULICIDAE) TO TENTS BAITED WITH HUMAN ODOR OR CARBON-DIOXIDE IN TANZANIA

Field studies on the response of Anopheles gambiae s.l. Giles and Anop heles funestus Giles to tents baited with human odour or carbon dioxid e were conducted in south-east Tanzania. Two exit traps and a CDC mini ature light trap set beside a bed net were used to sample mosquitoes t hat entered the tent. Human odour, pumped from an underground pit into a bed net attracted a similar number of mosquitoes as a bed net occup ied by a human male. Significantly fewer mosquitoes were caught in a t ent into which carbon dioxide (300 mi min(-1)) was pumped than in a hu man-odour baited ten: (9 and 27% for A. gambiae s.l. and A. funestus r espectively). A five-fold increase of the carbon dioxide concentration (to 1500 mi 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 h uman odour. Species identifications of A. gambine s.l. catches showed that A. arabiensis Patron prevailed and that the proportions of A. ara biensis/A. gambiae s.s. did not differ between treatments. It is concl uded that in the indoor situation described, human odour other than ca rbon dioxide is the principal cue to which these malaria vectors are a ttracted 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. gambine s.l.