Prolonged and variable copulation durations in a promiscuous insect species: No evidence of reproductive benefits for females.

ABSTRACT

Within promiscuous mating systems, copulation often functions as more than a means of fertilization, and copulation durations can vary widely. Copulating for prolonged durations can enhance both female and male reproductive success, but can also result in costs females of some insect species experience increased fecundity and fertility through male-provided nutrition during prolonged copulations, but also decreased longevity due to male-driven mechanisms. Here, for a common, promiscuous insect species (the squash bug, Anasa tristis), we first describe the range of copulation duration, which spans from 2 min to over 23 h. To investigate whether female A. tristis benefit from prolonged copulation, we next manipulated copulation duration and female diet, and we documented the resulting fecundity, fertility, and longevity of each female. We found no evidence that prolonged copulation durations affect female reproductive success. Females produced fertile eggs after a single 30 min copulation, and they subsequently produced fertile eggs for an additional 4 weeks. Our findings suggest that females do not benefit from prolonged copulations, that sperm transfer occurs very early during copulations, and that females can store sperm for long durations. Consequently, we suggest that female harassment avoidance and male mate-guarding may explain prolonged copulations in this species.