Date of this Version
Martin, CM. 2014. Costs of female mating behavior in the variable field cricket, Gryllus lineaticeps [dissertation]. Lincoln, NE: University of Nebraska-Lincoln. 104 p.
Female animals may risk predation by associating with males that have conspicuous mate attraction traits. The mate attraction song of male field crickets also attracts lethal parasitoid flies. Female crickets, which do not sing, may risk parasitism when associating with singing males. If parasitism risk is sufficiently high, it may affect the evolution of female mating behaviors. In this dissertation, I explore the interaction between the female variable field cricket, Gryllus lineaticeps, and the parasitoid fly, Ormia ochracea. To begin, I investigated whether female parasitism risk resulted from being near singing males. I found that females can become parasitized both by being near singing males when a fly arrives and by picking up previously deposited larvae when assessing males. Female crickets benefit from mating with males with high chirp rate song, but high chirp rate song attracts more flies. By caging male-female pairs above speakers broadcasting songs of different chirp rate, I found that females near high chirp rate song were more likely to be parasitized. Females with stronger preferences should thus incur higher costs. For fly parasitism to have a large effect on female mating behavior, it would need to affect fitness. I conducted a study to determine whether being parasitized affected female lifetime fecundity; I found that being parasitized reduced lifetime fecundity by over 90%. With parasitism occurring in a mating context, parasitism being more likely when near preferred males, and parasitism reducing fitness, it should impact female cricket mating behavior. I conducted a study to determine whether females from a highly parasitized population discriminated between male songs of differing chirp rate; I found that they did not prefer high chirp rate song to intermediate chirp rate song, which is contrary to what would be expected based on benefits alone. This dissertation shows that the risk to female crickets of becoming parasitized is likely an association cost that has a large impact on female fitness and could affect female mating behavior.
Advisor: William E. Wagner, Jr.