Flight behavior of Anopheles gambiae mosquitoes during arrival and bloodfeeding on human hosts

Like most malaria vectors, Anopheles gambiae is nocturnally active and its behavior is not easily observed. Though host-oriented flight in this and other mosquitoes is mediated by attractant cues from host skin and exhaled breath, knowledge of short-range host seeking flight has been obtained mostly in wind tunnels or relatively small-scale laboratory assays. Using a novel large-scale camera system illuminated with infrared light, we directly tracked and recorded hungry female An. gambiae in free flight during approach and landing on human volunteers in an experimental hut at a remote field location in Tanzania.  Most mosquitoes approached sleeping humans via a typical route, suggestive of a response to convective air currents. After landing, mosquitoes made short ‘bouncing’ flights across several locations on the volunteer’s body prior to selecting a site to bite, allowing a comparison of landing and biting rates between different body regions.  Flight responses to hosts protected by insecticide treated bed nets were also examined. Similar behaviors were seen at the bed net surface as at the unprotected host, and mosquitoes persistently approached and contacted the net surface in response to the volunteer within. These data, showing the flight patterns of this important African malaria vector during the final key stages of its interaction with the human host, provide valuable information for designing novel intervention tools, particularly important for combatting the growing levels of insecticide resistance in the field.