Mate binding: male adaptation to sexual conflict in the golden orb-web spider (Nephilidae: Nephila pilipes)

To counter female resistance to mating and cannibalism, males of many animal species have evolved a variety of behavioural adaptations. Here we investigated a novel copulatory courtship behaviour, mate binding, in which the male deposits fine silk onto the female’s body in between copulation bouts, in an orb-web nephilid spider, Nephila pilipes. We hypothesized that mate binding might reduce female aggressiveness and sexual cannibalism and that both tactile and chemical cues play a role. We performed a series of mating trials, in which we blocked (1) the females’ tactile perception, (2) the females’ chemoreceptors, and (3) both types of communication. We also manipulated male spinnerets and thus male silk production. As predicted, mate binding reduced both female resistance to repeated mating and levels of sexual cannibalism. Our results suggest that both tactile and chemical cues are crucial for mate binding to succeed in rendering females less aggressive, but that tactile cues are more important. We conclude that mate binding prolongs total copulation duration, whereby the male maximizes his paternity. Therefore, mate binding may serve as a mechanism countering sexual conflict over repeated mating and sexual cannibalism.