Acoustical Courtship Signals and Sexual Success in Irradiated Caribbean Fruit Flies (Anastrepha suspensa) (Diptera: Tephritidae)

Abstract

The effects of radiation on the two acoustical sexual signals of the Caribbean fruit fly, Anastrepha suspensa (Loew), were examined by irradiating flies at 2.5, 5, 7.5, and 10 kR 2-26 h before emergence and noting the effects on sound production and sexual behaviors. The pulse train intervals of the calling song increased with dosage, while the propensity to produce the sound decreased. The pulse trains of control songs consisted of two frequencies. The lower of these frequencies became lower yet with increased radiation but the higher frequency was unchanged. When flies were irradiated 24-48 h before eclosion, low frequency sounds decreased in proportion and often were absent altogether. The fundamental frequency of the precopulatory song was also lower in flies irradiated with higher dosages. The pulse trains were longer in 10 kR irradiated flies, and may be indicative of relative sexual incompetence. Several of the changes in the sound production of irradiated flies may make them less effective as sexual advertisements. These include increased pulse train interval, decreased calling sound propensity, and lowering of the sound frequencies. However, our measures of sexual success, time after introduction until mating, mating attempts, and mating duration showed no significant relationship with radiation dosage.