Stonefly duets: vibrational sexual mimicry can explain complex patterns

Stoneflies of the suborder Arctoperlaria exchange vibration signals for intersexual communication. The exchange takes the form of a duet with a male Call and female Answer. Some species and populations have three-way duets, with the male responding to the Answer with a third signal, termed Reply. We review duet descriptions of 106 species in terms of their temporal organisation and mate guarding tactics as identified by Bailey ( 2003 ), and propose a functional explanation in terms of concealment of the female for three recurrent phenomena: (1) In the case of large temporal overlap between Call and Answer, the overlapping part of the Call masks the Answer; (2) In three-way duets, the Reply mimics the female; (3) In a Call with two distinct phases, one phase mimics the female. It turns out that the Reply can be interpreted as mimicking the Answer in virtually all three-way duets. In two-way duets with a diphasic Call, the first phase typically mimics the Answer. Three-way duets with a diphasic Call are heterogeneous. Evidence for eavesdropping behaviour comes from the observation that males of the genus Zwicknia produce a Call in response to duetting sequences more often than in response to single male Call signals. We conclude with proposals for further research.