Acoustic studies on the mechanism of sound production in the mating songs of the melon fly,Dacus cucurbitae Coquillett (Diptera: Tephritidae)

The sound production mechanism in the male mating songs for the melon flyDacus cucurbitae Coquillett was acoustically investigated to determine whether sounds resulted from free wing-fanning or stridulation produced by contact between wing and abdominal pecten. Waveforms in the songs of normal (pecten-present) males showed more complex vibrations than those of pecten-removed males. The total harmonic distortion in normal songs was greater than that of the pecten-removed songs. Female (pecten-absent) songs showed different sound signatures on the oscillogram and frequency spectrum from normal male songs. The female songs had more harmonic components than the normal male songs. These results suggest that wing/pecten stridulation of normal male songs produces complicated wing oscillations with a small number of harmonics of near-periodic waveforms and a high harmonic distortion. They also suggest that the free wing-fanning observed during female and pecten-removed male songs produces simple and uniform wing oscillations with many harmonic contents of complex-periodic waveforms and low harmonic distortion. Despite the occurrence of some acoustic differences, pecten-removal did not positively influence the rate of copulation.