3-D flight behaviour of the malaria mosquito Anopheles gambiae s.s. inside an odour plume

Abstract

A wind tunnel and a novel auto detecting digital video system were used to study the flight behaviour of the nocturnal malaria mosquito Anopheles gambiae Giles sensu stricto. Females of this anthropophilic mosquito need to locate a host to obtain a blood meal in order to develop eggs. This host-seeking behaviour is mainly guided by olfactory stimuli, but little is known to what extent these stimuli affect flight and landing parameters. In this study single female mosquitoes were exposed to natural and synthetic human odours in a wind tunnel. Flight behaviour was digitally recorded and with the use of computer programmes the 3-dimensional (3-D) flight track of the mosquito was reconstructed. From the obtained tracks, the amount of plume contact, average flight speed and flight angles were calculated. Mosquitoes were found to significantly reduce their flight speed, trackand course angle when they were inside a plume of odours. Drift angle was not different inside and outside the odour plume. The flight speed was reduced when the mosquitoes came nearer to the odour source. The observed responses to host-stimuli can be explained by the nocturnal activity pattern of this mosquito. Reducing flight speed and course angle may be an efficient strategy to stay inside the trail of odour molecules when flying in the dark. It is important to know more about the flight behaviour of this malaria vector in response to odours, because it may help in the development or improvement of odour-baited mosqui