The ‘hot male’ hypothesis: do female crickets prefer males with increased body temperature in mate choice scenarios?

Insects have been extensively used as model systems to study mating preferences based on variation in acoustic signals. In many species, females perform phonotaxis towards attractive, long-range acoustic signals produced by males, whereas the final mating decision is based on an assessment of additional, multimodal, close-range cues. The production of acoustic signals is costly, because invested energy is inefficiently converted into acoustic power. Here, we investigated whether heat released as a by-product during song generation might serve as an additional cue during mate choice decisions. Males that broadcast highly energetic calling songs increased their thoracic temperature considerably above ambient temperatures. The use of this additional cue would turn the acoustic signal into an inherently bimodal one, indirectly indicating the quality of the sender. To test this hot male hypothesis, we performed trackball and Y-maze experiments with Anurogryllus muticus. For comparison, additional trackball experiments were conducted with Gryllus bimaculatus females. In all paradigms, females of both species showed no evidence of a preference for hot males and, therefore, we conclude that increases in thoracic temperature do not seem to play a role as a multimodal component in mate choice decisions in A. muticus.