The Form and Function of Acoustic Courtship Signals of the Papaya Fruit Fly, Toxotrypana Curvicauda (Tephritidae)

Abstract

The male papaya fruit fly, Toxotrypana curvicauda Gerstacker, makes two acoustic signals during courtship: (1) the approach song consists of one to five pulse trains (sound bursts) and is directed at females prior to mounting; (2) the precopulatory song consists of one to seven pulse trains produced immediately after mounting the female. Unlike the somewhat similar "calling song" of the Caribbean fruit fly, the papaya fruit fly's approach song is monotonic, a character which may be due to an absence of selection for escaping vegetation-filtering. Virgin females, but not males, become less active in the presence of broadcast approach sounds, suggesting that the proximate effect of the song is to depress locomotion in the female. Large males pair more often than small and the sound pressure level of large male approach songs is louder. Females may detect the size/vigour of a singer by his song, and such sounds may have evolved as sexually selected male advertisements rather than a means of species isolation.