Pheromone that keeps young bees at home

Old forager bees exert some sort of influence on young nurse bees keeping them at home -- but how do they do it? Zachary Huang and others have discovered the answer.

Experiments showed that if a significant number of forager bees didn’t come home, the young nurse bees would mature ahead of schedule and head out to become foragers themselves. If the older bees were kept inside more than usual -- as in an extended rain shower -- fewer young bees would mature, but instead stick to brood care.

Pheromones were suspected, but couldn't be identified. Many quick-acting “releaser” pheromones are known, but the researchers suspected “primer” pheromones that worked to keep bees at home are slower-acting.

Then they discovered that forager bees carry a chemical called ethyl oleate in the abdominal reservoir in which they store nectar. Young bees don't have ethyl oleate and it is the primer pheromone that keeps them at home.

Forager bees load up on ethyl oleate when they’re buzzing about gathering food, but don’t digest it. The forager bees feed the chemical to the worker bees, and the ethyl oleate keeps them in a teenage state, sort of like being grounded to watch the younger siblings. As the old bees die off, the chemical no longer is fed to nurse bees. Eliminate ethyl oleate and the bees mature into foragers.

... Huang said the system makes sense for the health of the hive. Young bees -- those in the first two to three weeks of life -- are biologically better suited for brood care, thanks to some boosted blood protein. Bees forced out too early aren’t great navigators, and since foraging is dangerous, they risk dying before their time.

Zachary Huang of Michigan University may be a familiar name to Propolis readers -- he's the one with the brilliant bee pictures.