Courtship song components affect male and female Drosophila differently

The responses of male and female Drosophila melanogaster to male courtship songs were investigated by videotaping single sexed groups of flies as they were exposed to simulated sounds: pulse, sine, pulse sine and rhythmic, and controls: white noise (males only), and silence (females only). Patterned sounds (1-min silence, 1-min sound) were delivered for 19 min: (1) in 6-dB steps from 60 to 108 dB; and (2) at 84 dB. This method enabled sound intensity effects to be distinguished from the effects of time of exposure. Pulse, pulse sine and rhythmic songs significantly increased male locomotory activity and male-male courtship interactions compared with initial measurements at no sound. Sine song had similar effects but to a lesser degree. White noise resulted in complete cessation of movement. Females behaved differently from males: there was more movement at initial no sound, followed by decreased movement over time in all conditions. However, sine and rhythmic songs differed significantly from the silent control condition and maintained activity at a high level. An exposure of 1 min to pulse sine song at 84 dB made females slow down showing that intensity level, and not length of exposure, was the critical stimulus. It is suggested that the different responses of males and females to the various components of male courtship song are adaptive: female movement initially attracts males; while increased male movement plus decreased female movement enhances mating. (C) 1995 The Association for the Study of Animal Behaviour