Lack of perceived sperm competition risk increases post-copulatory song in Pacific field crickets

Mate guarding enables males to bias fertilization, increase their share of paternity, and thereby enhance reproductive success. When the risk of sperm competition is high, males may benefit from investing more in guarding behaviors. While some species physically restrain females during guarding, others use more passive tactics. Male Pacific field crickets (Teleogryllus oceanicus) sing after mating to entice females to stay, even though they cannot mate again immediately. Post-copulatory song effectively keeps females in proximity, prolongs spermatophore attachment, and ultimately enhances male reproductive success. We investigated whether cues about the risk of sperm competition determine male investment in post-copulatory song. Additionally, we studied whether hearing cricket calls either during rearing or immediately before mating modified the listeners' behavior. Males exposed to acoustic cues of male competitors during rearing or immediately before mating were not more likely to sing post-copulatory songs. However, among those males that did sing post-copulatory songs, those exposed to song during rearing had a greater latency to begin singing and overall spent less time singing post-copulation than males exposed to silence. These findings suggest that early-life social environments shape long-term mating strategies, while immediate cues have limited influence on post-copulatory mate guarding behavior.