Song recognition in female bushcrickets Phaneroptera nana

Unlike most acoustic systems evolved for pair formation, in which only male s signal, in many species of phaneropterine bushcrickets both sexes sing, p roducing a duet. We used the duetting species Phaneroptera nana as a model to explore the cues in the male's song that elicit the female's phonorespon se. Different synthetic male songs (chirps containing 2-6 pulses) were pres ented to Ph. nana females, and their acoustic responses were recorded. The threshold of the female response is lowest at 16 kHz (best frequency), coin ciding with the dominant frequency of the male song. The specific amplitude pattern of consecutive pulses in the song of the male is not a critical fa ctor in his signal. That is, songs with both a normal and a reversed order of pulses equally elicit a female response. By systematically deleting puls es from the synthetic male chirp, we found that at least two pulses are nee ded to elicit a female reply. Under no-choice conditions, increasing the nu mber of pulses did not result in a higher probability of response and did n ot change the latency of the response; i.e. two pulses are necessary and su fficient to elicit a female response. The range of pulse duration that elic its a female response is 0.2-25 ms, and the inter-pulse silent interval ran ges from 5 to 30 ms.