To copulate or not? The importance of female status and behavioural variation in predicting copulation in a bumblebee

Abstract

Qualitative variation in female reproductive status and quantitative variation in courtship behaviour may both be important in determining whether copulation occurs after a mating interaction. However, integrated studies of these factors are rare. We examined whether female behaviour, male courtship behaviour and female reproductive status affect, on their own or together, the outcome of mating trials in the bumblebee, Bombus terrestris. We used insemination techniques to manipulate the status of females, enabling us to dissect the relative roles of previous behavioural experience and actual reproductive status of females. Despite quantitative variation in male and female behaviour, the main predictor of copulation was female reproductive status. While two behaviours, female rejection of males and male attempts to copulate, explained 9% of the variation between trials in whether copulation occurred, on their own they could not predict whether mating occurred. Nonbehavioural factors, such as colony of origin and animal age, had no predictive power with respect to the occurrence of copulation. Our results suggest that, despite potential selection on males for courtship behaviour, quantitative within-species variation in the precopulatory behaviours we observed had little or no effect on whether copulation actually occurs. Rather, the reproductive status of females seems to be the most important determinant of copulation.