By Marlowe Hood, AFP
PARIS–Scientists revealed Wednesday the trigger that can plunge a colony of obedient and sterile worker bees dutifully serving their queen into a chaotic swarm of sexual rebellion and regicide. It’s in the beeswax, according to a study published in the British journal Royal Society Open Science.
Biologists have long puzzled at what, exactly, tips the ordered world of many social insects — rigidly divided by caste, function and hierarchy — into murderous mayhem of sometimes Shakespearean dimensions. In this case, the actor subject to observation and experimentation was Bombus terrestris, more commonly known as the bumblebee. In its steady-state “social phase,” a bumblebee colony is a paragon of efficiency that would make Amazon’s Jeff Bezos green with envy. “Workers and the queen usually just attend to their tasks peacefully,” explained Anne-Marie Rottler-Hoermann, a researcher at the Institute of Evolutionary Ecology and Conservation Genomics in Ulm, Germany, and lead author of the study. The workers — always female — focus selflessly on foraging, taking care of the brood, nest-keeping and maintaining defenses against potential aggressors. The queen does what queens do: allows herself to be pampered and fed by her offspring, while she lays eggs to produce more workers and the occasional male that may later mate with a virgin queen, known as a gyne. The Final Act Males are otherwise pretty useless. They play no role in the life of the colony, which they abandon shortly after emerging.
Born in the late summer, when most of the nectar-rich flowers are gone, these wandering Lotharios usually die within a few days. This clear division of labor and absence of sexual conflict “can be considered the main reason for the great evolutionary and ecological success of social insects,” Rottler-Hoermann said. With bumblebees, a typical colony — which has a life-cycle of less than a year — will grow to accommodate 150 workers and one queen.
But at a certain point something snaps, and the clockwork cooperation comes to an end.
The transition to the “competition phase” is quick — and sometimes brutal.