Close encounters: contributions of carbon dioxide and human skin odour to finding and landing on a host inAedes aegypti.
In a wind-tunnel study, the upwind flight and source location of femaleAedes aegyptito plumes of carbon dioxide (CO2) gas and odour from human feet is tested. Both odour sources are presented singly and in combination. Flight upwind along the plumes is evident for both CO2and odour from human feet when the odours are presented alone. Likewise, both odour sources are located by more than 70% of mosquitoes in less than 3 min. When both CO2and odour from human feet are presented simultaneously in two different choice tests (with plumes superimposed or with plumes separated), there is no evidence that females orientate along the plume of CO2and only a few mosquitoes locate its source. Rather, the foot odour plume is navigated and the source of foot odour is located by over 80% of femaleAe. aegypti. When a female is presented a plume of CO2within a broad plume of human foot odour of relatively low concentration, the source of CO2is not located; instead, flight is upwind in the diffuse plume of foot odour. Although upwind flight byAe. aegyptiat long range is presumably induced by CO2and the threshold of response to skin odours is lowered, our findings suggest that once females have arrived near a prospective human host, upwind orientation and landing are largely governed by the suite of odours from a human foot, while orientation is no longer influenced by CO2.
Department of Entomology, University of California, Riverside CA 92506 USA.
Emerson S
ES
Lacey
Department of Entomology, University of California, Riverside CA 92506 USA.
Anandasankar
A
Ray
Department of Entomology, University of California, Riverside CA 92506 USA.
Ring T
RT
Cardé
Anemotaxis; orientation wind tunnel; yellow fever mosquito