Sexual communication in the oriental fruit fly, Dacus dorsalis Hendel (Diptera: Tephritidae)

Results of the research on sexual communication in the Oriental fruit fly, Dacus dorsalis were reported in three chapters: 1) description and details of its sexual behavior, 2) determination of the significance of sexual signals for attracting members of the opposite sex and in successful mating, and 3) identification of the behavioral characteristics which make males attractive and successful in mating with females. Three major components in the sexual behavior included: 1) signal emission through male wing-fanning followed by the arrival of females; 2) courtship behavior involving male wing-fanning followed by attempted copulations; and 3) copulation. Further tests also showed that females that had mated once neither were attracted to males nor accepted Subsequent matings as readily as virgin females. By modifying either the male's ability in emitting sexual signals, i.e. modification of wing fanning, or the various sensory receptors in the females, i.e. the eyes for visual signals, the aristae for acoustic stimuli, and the antennae for olfactory cues, it was possible to investigate the separate modalities of sexual communication during the 1) attraction phase (i.e. the bringing together of the two sexes over a distance of about 50 cm), and the 2) courtship phase (i.e. signal emission at close range of about 6 cm). The wing fanning in males was found to play a significant role in the production of signals for the attraction of and mating with females. Experiments conducted in the females showed that acoustic as well as olfactory signals were crucial in attracting females to wing-fanning males, but only olfactory stimuli were important for mating acceptance of the females. Differential sexual success among males and female choice played an important role in the complex mating system in this species. Sexual success in males was measured in terms of ability to attract and mate with females. For the most part, both qualities could be found in the same male. It was also found that sexually successful males had the capability of signaling for a longer duration, and had the top rank in male-male aggressive interactions more frequently than other males. Thus, intermale competition could possibly be another component of sexual selection operating in this species. The results of this study provide baseline information that will be important for the development of more effective control and/or eradication methods for D. dorsalis as well as other related species.