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

Abstract

Sex role differences can influence ecological and evolutionarily important traits like activity level and behavioural flexibility. In bumblebees, female workers are the main foragers for the colony, whereas males (drones) have minimal responsibility. However, males become solitary foragers once they leave the colony, suggesting that increased activity level and behavioural flexibility are crucial for their survival. Here, we conducted a laboratory experiment to compare male and female bumblebees’ active time in a novel environment (using an ‘activity’ task) as well as their colour-reward associative learning ability and behavioural flexibility (with a simultaneous two-choice discrimination-reversal colour learning task). As predicted, males were more active in the novel environment than females. Males and females showed comparable performance in learning the colour-reward association, but males demonstrated enhanced behavioural flexibility when the reward contingency changed. Males’ active time may reflect their exploratory behaviour (e.g., pre-mating patrolling), and their enhanced flexibility suggests their readiness to find new profitable flowers when exploited flowers decrease in quality. These results highlight the importance of these behavioural and cognitive traits for males, which may increase their chance of finding mates and improve their foraging efficiency.