Male bumblebees (Bombus terrestris) are more explorative and behaviourally flexible than workers.

Abstract

Sex role differences can influence ecological and evolutionarily important traits, such as exploration and behavioural flexibility. In bumblebees, for instance, females (workers) are the main foragers for the colony whereas males (drones) have minimal responsibility. When males leave the nest, however, they become solitary foragers while searching for mates for reproduction. This suggests that increased exploration and behavioural flexibility are crucial for their survival and reproduction success. Here, we compared the exploratory behaviour and behavioural flexibility of male bumblebees (B. terrestris) with that of female workers in a laboratory. We measured bees active time in a novel environment in an exploration task and their colour-reward associative learning ability and behavioural flexibility in a simultaneous two-choice discrimination-reversal colour learning task. As predicted, males were more active (thus explored more) in the novel environment than females. Performance of a colour-reward association learning was comparable between males and females, but males demonstrated enhanced behavioural flexibility when the reward contingency changed. Males used the win-stay, lose-shift strategy, making fewer errors (being more flexible) than females. Males explorative behaviour may be related to their pre-mating patrolling behaviour in the wild. Their enhanced flexibility suggests their readiness to find profitable flowers when other flowers decrease in quality. These results highlight the importance of exploration and behavioural flexibility for males, which can increase their chance of attracting mates for reproduction and maximising their energy during foraging. Results provide insights into how different traits are related to sex roles in various fitness-related contexts.