Mosquito (Dipteral Culicidae) flight behaviour near conspicuous objects

Abstract

Field studies were conducted in Florida to investigate the behaviour of night-flying mosquitoes including Aedes sollicitans (Wlk.), Ae. taeniorhynchus (Wied.), Anopheles atropos D. & K., An. crucians Wied., Culex nigripalpus Theo., Culiseta melanura (Coq.), Deinocerites cancer Theo., Psorophora columbiae (D. & K.) and (Uranotaenia lowii Theo.) in relation to visually conspicuous objects. Adults of all species except Ae. sollicitans were taken in greater numbers in a large weathered plywood suction trap covered with black panels than in one without panels. However, both traps were attractive, as a transparent plastic suction trap covered with weathered plywood panels took larger numbers of all species except U. lowii than a transparent trap without panels. Buried suction traps furnished with visible risers (extensions) that made captures at 1·2 m elevations always captured proportionately larger numbers than buried traps with visible baffles that captured mosquitoes at ground level. A woodland species, C. nigripalpus, was captured in larger numbers toy traps furnisihed with visible risers and baffles than in traps furnished with transparent risers and baffles; however, collections of field species, e.g. Ae. taeniorhynchus, were smaller. The distribution of blood-fed and gravid females in collections from these traps provided some evidence that blood-seeking females are more responsive to visible objects than engorged or gravid females. These results are compatible with the hypotheses that (1) mosquitoes are attracted from a distance to visible objects, (2) in close proximity an avoidance action occurs and mosquitoes then pass over or around the visible object and (3) woodland species approach visible objects closely (<30 cm), whereas field species pass by at greater mean distances. Consequently, a larger percentage of visually attracted woodland mosquitoes than of visually attracted field species will be captured by suction traps. Depending upon trap design and specific behaviour, increasing the visibility of a suction trap can either increase or decrease trap collections