Meeting Abstract

82.3  Thursday, Jan. 7  Male mate choice in black widows: chemical and physical cues allow males to avoid sexual cannibalism by poor-condition females JOHNSON, JC*; TRUBL, P; BLACKMORE, V; Arizona State University West Campus jchadwick@asu.edu

Extensions of Bateman’s rule predict male mate choice should evolve as male investment in mating increases. Spiders use chemical cues to avoid predators and locate mates, but it remains unclear whether males courting sexually cannibalistic females use chemical cues to make risk-sensitive mating decisions. Here we test the prediction that cues of female foraging success (“fed cues”) encourage male courtship in the black widow spider (Latrodectus hesperus). In addition, we test the prediction that previous foraging success reduces pre-copulatory sexually cannibalistic attacks/kills by females. Results show that, in both the absence and presence of females, males courted significantly more in webs containing fed cues. However, when well-fed females were switched to the webs of starved females and vice versa, males preferred courting well-fed females despite the lack of fed cue. Male preferences for well-fed females appear adaptive. Starved females were significantly more likely to attack and kill males before mating, and males were attacked and killed most often by starved females inhabiting webs containing fed cues. We conclude by noting that sexual cannibalism offers a model system wherein chemical communication arms races between predator and prey have broad implications such as the effects on sexual selection described here.