Mating in the mosquito, Anopheles gambiae s.l.

ABSTRACT. Swarming behaviour in the Anopheles gambiae complex was observed in the field, in the Gambia, West Africa, and in the laboratory. Naturally occurring swarms of A.melas were seen in a clearing at the edge of mangrove swamps close to their breeding sites. Males could be induced to swarm over artificial 'markers' within this 'arena' but not outside it. Females were observed entering the swarm and mating. In the laboratory, in an artificial 'dusk', male A.gambiae s.str. swarmed over a black marker on the floor of their 1.2-m cube cage. In contrast to the males, females made only short flights over the marker, performing brief turning movements at its edge. It is proposed that swarming brings about the aggregation necessary before short-range attraction can take place, and that, in nature, anopheline mosquitoes orientate visually first to an arena and then to a marker within the arena. Female behaviour can be interpreted as a process of scanning possible swarm sites until mating is achieved.