Duetting strategies of phaneropterine bushcrickets

Thomas Hammond

Research output: ThesisDoctoral Thesis

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Abstract

[Truncated] Many species of the subfamily Phaneropterinae (Tettigoniidae: Orthoptera) adopt a system of acoustic duetting to facilitate mate location. More typically in the Tettigoniidae (bushcrickets or katydids), males call and silent females select and locate males. In a phaneropterine duet, the male produces an acoustic call which is answered by the female, usually with a number of short clicks. The male, upon hearing the female response, will commence searching for the female. Thus, by adopting the system of a duet, costs associated with mate searching are shifted from the female to the male. In this thesis I investigate duetting behaviour in three species of phaneropterines belonging to the genus Caedicia. The aim of this study is to test hypotheses regarding the evolution of calling and searching strategies. We expect that males and females will pursue mating strategies that will maximise their reproductive output given their current condition.

I investigate the variation of mating tactics by females by studying female behaviour in a species of Caedicia, identified here as Caedicia sp. 10. This study shows that females modify their acoustic response in terms of the number of clicks produced. As females change the number of clicks they produce, they similarly alter the timing of their response and the rate of click production. Adjusting the reply in this way maintains the response within, and close to the centre of, a critical species-specific time window, which is the period of time following the male call during which the male will recognise a female response. To adjust the timing of the response, which may be produced while the male is still calling, females use one of two cues within the male call. A female can time her response from either the end of the male call, or from a syllable produced within the call. A second question examines the female’s response to male calls of different intensity, which is a cue indicating distance between duetting partners. This experiment showed that females increase the number of clicks they produce as male call intensity is lowered.
Original languageEnglish
QualificationDoctor of Philosophy
Publication statusUnpublished - 2003

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