Eavesdropping and defensive auditory masking in an Australian bushcricket, caedicia (Phaneropterinae : Tettigoniidae : Orthoptera)

We investigated the potential for a novel alternative male tactic in Caedicia, an Australian genus of duetting phaneropterine bushcrickets (Orthoptera: Tettigoniidae: Phaneropterinae). Males listen to and track females as they reply to the calls of other males, using both the male call and the female reply to initiate their own searching behaviour. We describe this behaviour as eavesdropping. Calling males produce a high intensity chirp following their calling song, which has no apparent effect on female responsiveness. We test the possibility that this loud chirp acts to defend the temporary pair bond, established between the calling male and the duetting female, by preventing other males from hearing the female reply. We suggest means by which the calling male may be able to hear the female reply whilst producing the masking chirp. This behaviour may be considered a form of pre-copulatory acoustic mate guarding.