Natural History and Acoustic Behavior of a Gregarious Cricket

The cricket Amphiacusta maya (Gryllidae: Phalangopsinae) was studied in the field in Costa Rica and in the laboratory. In the seasonal habitat of Guanacaste Province, C.R., adults are found only during the first 4 months of the rainy season. Adults and subadult nymphs form aggregations each dawn and disperse at dusk. Within the aggregations, males chirp, fight other males, and occasionally mate with females. The acoustic behavior of these crickets differs from that of the better-known field crickets in three major ways. First, males do not produce a calling song. Second, the chirps given in aggressive and courtship contexts are nearly indistinguishable spectrally and temporally. Third, the species-typical chirp does not elicit phonotaxis in adult females or in nymphs. Possibly the calling song would no longer provide a selective advantage to males because females are in their vicinity regardless of male behavior. Additionally, acoustic signal similarity may be a result of selection for aggressive signalling in both contexts (aggression and courtship). Thus these modifications in acoustic signals may be adaptations to a gregarious mating system.