Scientists around the world are trying to figure out why honey bee populations are declining—a pattern known as colony collapse disorder.
They’ve identified pathogens, pesticides, and nutritional deficits as stressors, but it’s still a mystery why bee colonies sometimes collapse rapidly, rather than decline slowly, leaving bee keepers with an empty hive box.
An international team recently used radio tracking to follow thousands of bees in Australia throughout their lives hoping to solve the mystery. They found that bees reacted to stress by starting to forage when young, but the young precocious foragers did not cope well with growing up too fast.
“Bees display a predictable pattern of behavioral development,” says Eirik Søvik, a postdoctoral research associate at Washington University in St. Louis. “They begin adult life performing in-hive tasks, shifting to foraging when they are two or three weeks old. Varied stressors, such as loss of foragers, starvation, or disease, can cause bees to accelerate their behavioral development and forage precociously.”
Precocious foragers completed fewer foraging trips in their lifetime and experienced a higher rate of early death, putting pressure on the colony’s social structure. This disrupted the colonies’ finely balanced social dynamics, triggering a population collapse.
“Bee colonies contain a precise balance of bees specialized in the different roles the society needs. If that balance is upset by young bees starting to forage early, sometimes the colony cannot cope,” says Andrew Barron of Macquarie University and senior author of the study published in PNAS.
“There is a breakdown in division of labor, and loss of the adult population, leaving only brood, food, and few adults in the hive.”
With their greater understanding of the collapse process, the authors are now exploring possible strategies to improve colony resilience including rescue packages for sick colonies, and new sensors to detect colonies at risk of failure.
“Other factors previously implicated in colony collapse, all have different treatments,” Søvik says. “Our study suggests that it might be better to pursue more general preventative measures.”
Source: Amy Macintyre/Macquarie University via Washington University in St. Louis