The function of antennation as courtship in bean beetles

During mating, male bean beetles (Callosobruchus maculatus) engage in antennation, a behavior where they rapidly tap the female's back immediately before intromission. Behavioral observations suggest that antennation may function as courtship in this species, but this has not yet been empirically tested. Here we sought to determine the function of antennation by investigating whether females prefer higher antennation intensity. We tested this by measuring and comparing mating behaviors of females who mated with either control males or males where one antenna had been ablated. By ablating one of the male's antennae, we were able to manipulate the female's perception of antennation intensity. We found that when females mated with a single male, the ablation treatment had no effect on the female preference behaviors we measured (latency to copulate, kicking behavior, and clutch size). However, when females were allowed to mate twice, once with a control and once with a manipulated male, we found that females laid more eggs when they mated with a control male. Overall, we found that females show a preference for more intense antennation behavior by increasing their clutch size when they mate multiply. This supports the hypothesis that antennation functions as courtship in this species.