Northern Illinois University DeKalb, Illinois, United States
In some insects, already mated individuals are avoided as mates. In the present study, the effects of female and male mating status were examined in the well-studied parasitoid wasp Nasonia vitripennis.
In N. vitripennis, mated females are less likely than virgins to respond to courtship by males once mounted. If a male mounted a virgin female first, the mating was almost always completed; whereas if he mounted a mated female, mating was completed about half the time. Nevertheless, males did not avoid or delay contacting or mounting mated females even when a virgin was simultaneously present. Hypotheses to explain this will be discussed.
To examine effects of male mating status on mating outcomes, virgin males and mated males were individually presented with a single dead female, which males will readily try to mate. Thus, the male’s behavior was in the absence of any influence of female behaviour or competition with other males. In this situation, mounting was not less likely or slower for the males that had just mated than for the virgin males.
However, matings with males that had just mated resulted in a reduced proportion of daughters relative to matings with males that had to wait a day to remate. In N. vitripennis, daughters develop from fertilized eggs; sons develop from unfertilized eggs. Sex ratio results of the present study are consistent with the reload hypothesis, i.e., with males needing time to move sperm to where it becomes available for a subsequent mating
