Convergent song preferences between female field crickets and acoustically orienting parasitoid flies

Traits that increase the attractiveness of males to females often make them more conspicuous to predators. In the field cricket (Gryllus lineaticeps), males are attacked by parasitoid tachinid flies (Ormia ochracea) that locate males through their calls. Female flies larviposit on crickets and the larvae burrow into and feed on the cricket, killing the cricket upon emergence. To determine whether traits preferred by females increase a male's risk of attracting a predator, I examined the effect of variation in male singing behavior on mate and predator attraction. Both female crickets and female flies preferred male calling songs with higher chirp rates, longer chirp durations, and higher chirp amplitudes. In addition, both female crickets and female flies preferred male calling songs with higher chirp rates and longer chirp durations, even when these songs were of lower amplitude. These results suggest that sexual selection by female choice will favor the evolution of higher chirp rates and longer chirp durations. However, call types that increase a male's attractiveness to females also appear to increase a male's risk of attracting parasitoids. Sexual and natural selection appear to have opposing effects on the evolution of male singing behavior in this species.