Effects of sound on swarming male Psorophora columbiae.

Male Psorophora columbiae were shown to respond to sound during swarming. The responses consisted of abrupt changes in flight speed and direction. Tones with frequencies of 200 to 425 Hz were attractive to males over a distance of at least 1 m. Male mosquitoes responded better to tones with sine waveforms than they did either to square waveforms or triangular waveforms. Swarming males became accommodated and no longer responded to sounds presented for 5 seconds or longer. Based on observations of field populations of swarming Ps. columbiae, it appears that males use sound waves to locate females, but additional factors seem to be required for males to initiate the actual copulatory behavior. Also, males appear to use sound to maintain their position and spatial relationship within the swarm.