Males of social insects can prevent queens from multiple mating

During copulation, males of Bombus terrestris fill the queen's sexual tract with a mating plug after transferring their sperm. The sticky secretion is produced by the male's accessory glands and disappears within a couple of days. Experiments now show that the primary function of the plug is to redu ce the subsequent mating probability of the queen. The plug is not efficien t in preventing sperm migration into the spermatheca. Due to its low energe tic value, the plug is also unlikely to serve as a nuptial gift. This type of male interference with female mating propensity has so far not been foun d in social insects. This finding could, at least tentatively, explain why females of B. terrestris may not be able to take advantage of the demonstra ted benefits of multiple mating. Furthermore, such male interference could be a more general phenomenon in social insects. with obvious ramifications for the evolution of polyandry in this group.