Sexually transmitted parasites and host mating behavior in the decorated cricket

Sexually transmitted diseases play a potentially important role in the ecology and evolution of host mating behavior. Here, we use a sexually transmitted nematode-cricket (Mehdinema alii--Gryllodes sigillatus) system to examine the effects of parasitism on host mating activity and female choice. Previous work has shown that infected male crickets produce a significantly smaller nuptial gift (spermatophylax) than uninfected males. This is expected to result in reduced spermatophylax feeding duration and early ampulla removal. Here, we hypothesize that the parasite-mediated reduction in spermatophylax size will consequently shorten female intercopulatory interval. We predict that females mated to infected males will exhibit a shorter intercopulatory interval than females mated to uninfected males. To test this hypothesis, we experimentally measured the behavioral responses of females mated to uninfected and infected males. We found no significant difference between female handling of the spermatophylax and ampulla from infected versus uninfected males. Although the duration of spermatophylax consumption is positively correlated with the duration of ampulla attachment, neither of these variables is correlated with female intercopulatory interval. Intercopulatory intervals for females previously mated with uninfected versus infected males are not statistically different. We conclude that parasitism in male G. sigillatus does not influence female intercopulatory interval or male mating success. We found no evidence for female mate choice based on male infection status. The lack of female choice is consistent with theoretical predictions involving parasites that are sexually transmitted. Copyright 2005.