Courtship song in Drosophila melanogaster:: a differential effect on male-female locomotor activity

The courtship song of male Drosophila melanogaster Meigen, 1830 is involved in species recognition and sexual stimulation. This signal is usually addressed to the female to reduce her locomotor activity, thereby facilitating copulation. However, no accurate quantification of her locomotion has been made. To examine the effect of courtship song on locomotor behaviour of both sexes, we used a video-tracking system that allowed for the quantification of two indicators of activity level: distance moved and movement duration. First, we showed that the broadcast of the courtship song alone produced no effect on female locomotion. Females reduced their locomotor activity only when acoustical stimulation was placed in a natural courtship context (i.e., in the presence of a male). This suggests that the sum of visual, tactile, acoustic, and chemical stimuli provided by the male may act together to trigger female receptivity. Second, our playback experiments showed a strong stimulating effect of courtship song (particularly of the pulse component) on the locomotor activity of isolated males, suggesting that this signal probably plays a role in male stimulation. Courtship song has an opposite effect on male/female locomotor activity in D. melanogaster.