Male black widows court well-fed females more than starved females: silken cues indicate sexual cannibalism risk

Abstract

Male mate choice is predicted to evolve as male investment in mating increases. Thus, taxa in which males pay a high cost for mating offer researchers an ideal system to test traditional sex roles. Males courting potentially sexually cannibalistic females may be under strong selection to bias their courtship efforts away from hungry females that may be more likely to attack. Here we tested the prediction that web-based chemotactile cues of recent female foraging success influence male courtship in the black widow spider, Latrodectus hesperus. In addition, we tested the underlying assumption that previous female foraging success reduces precopulatory sexually cannibalistic attacks. We found that males courted well-fed females significantly more than they did starved females, and that this bias was maintained in the absence of the female when males encountered only (1) cues from female webs and (2) cues from female silk after web architecture had been eliminated. A nonsignificant courtship bias in favour of well-fed females was also evident when these females were transplanted to the webs of starved females. Male courtship biases in favour of well-fed females appear adaptive, as starved females were significantly more likely to attack males before mating. We conclude by noting that sexual cannibalism offers a model system wherein the exploitation of cues of predation risk have unique implications such as the effects on male courtship preferences seen here.