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 lin eaticeps), males are attacked by parasitoid tachinid flies (Ormia ochr acea) that locate males through their calls. Female flies larviposit o n 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 th e effect of variation in male singing behavior on mate and predator at traction. Both female crickets and female flies preferred male calling songs with higher chirp rates, longer chirp durations, and higher chi rp amplitudes. In addition, both female crickets and female flies pref erred male calling songs with higher chirp rates and longer chirp dura tions, even when these songs were of lower amplitude. These results su ggest 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 increa se a male's risk of attracting parasitoids. Sexual and natural selecti on appear to have opposing effects on the evolution of male singing be havior in this species.