Same-sex sexual behaviour and mistaken identity in male field crickets, Teleogryllus oceanicus

A variety of adaptive and nonadaptive hypotheses have been proposed to explain the maintenance of same-sex sexual behaviour (SSB) in animals. Adaptive hypotheses have gained limited support in insect systems, and the behavioural mechanisms underlying the expression of SSB are not well understood. A frequently suggested mechanism is that SSB in insects occurs as a result of mistaken identity. We used the field cricket, Teleogryllus oceanicus, to evaluate adaptive hypotheses for the existence of male SSB and then dissect its proximate behavioural origins. We tested whether male SSB mitigates the costs of intrasexual aggression or facilitates the establishment of social dominance. We found no support for either of these adaptive hypotheses. However, the social environment males experienced modulated their expression of SSB. Males with recent experience of females in their social environment were between three and eight times more likely to engage in SSB in subsequent encounters with males, compared to males that experienced either another male or no social contact. Our results provide evidence that male SSB in T. oceanicus arises as a result of mistaken identity driven by weakened sex discrimination when there is a perception of females available for mating, and they highlight a pivotal role for behavioural plasticity in the expression of SSB.