Altruistic worker bees usually abstain from reproduction — unless they have a shot at making a royal baby.

Michael Holmes at the University of Sydney in Australia and his colleagues monitored the fertility and breeding habits of seven colonies of Western honeybees (Apis mellifera). It was thought that workers (who are all female) refrain from breeding and instead raise the queen's brood, which is better for the colony's overall success. But the researchers found that overall, 4.2% of males (drones) are produced by workers, a level 40 times greater than that typically reported. Furthermore, just before virgin queens set out to establish their own hives, a worker baby boom occurs and the number of worker-produced drones peaks at more than 6%.

The authors speculate that workers may risk breaking rank for the chance of producing a new queen's future mate.

Mol. Ecol. 22, 4298–4306 (2013)