Female reply strategies in a duetting Australian bushcricket, Caedicia sp. (Phaneropterinae: Tettigoniidae: Orthoptera).

Duetting is common between the sexes of phaneropterine bushcrickets (Phaneropterinae: Tettigoniidae: Orthoptera). In this paper we describe the complex duet of an undescribed Australian species within the genus Caedicia: The male's call consists of three parts, of which the final part contains information of the species' identity and most reliably elicits the female's response. The timing of her reply usually occurs within a period of about 1 s after the male has completed his signal but may also start during the male's call. Females reply with brief clicks ranging from 1 to >10, adjusting this reply number to changes in male call duration and intensity. By using computer-synthesised calls, we discovered that the female times her reply both from cues within the male call, when she starts the reply before its conclusion, and from the end of the call, in the case where the reply follows the male call. As the number of clicks in the reply increases so the interval between clicks decreases; the female fits her entire reply within a critical time window following the male's call. The male call intensity had a marginal effect on female reply strategy. We suggest a model based on levels of female motivation, by which females may set the number of clicks in reply as well as the reply latency.