Reproductive potential and its behavioural consequences in orphaned bumblebee workers (Bombus impatiens)

International audienceAbstractThe supposition that aggression in orphaned workers is used in a battle over reproductive rights was evaluated for Bombus impatiens. Ovarian development was experimentally stimulated or inhibited in orphaned sisters. The manipulation translated into differences in egg laying. Two groups of pairs differed as to whether both or just one of the workers had developed ovaries. The prediction that workers with higher reproductive potential in the unmatched groups would show less aggression overall, compared to those in the matched groups, was not borne out. Nonetheless, butting frequency by the worker with developed ovaries was significantly reduced, as was oophagy, whereas the butting frequency by the worker with undeveloped ovaries was significantly increased. In contrast with Bombus terrestris, overt conflict does not end with one worker gaining a reproductive edge. The results challenge the premise that aggression is a means of preventing reproduction by kin: aggression may possibly serve to promote it