Honey bee colonies organize work without any leader assigning tasks, but scientists have now discovered that specific circuits in the brain help control this process. (representational image)
Honey bee colonies operate in an organized manner even though there are no bees telling others what to do. Young bees take care of the queen and baby bees, while older bees build and guard the hive, while the largest workers fly off to collect food.
Scientists have known this pattern for a long time, but they didn’t know how bee brains control these changes.Researchers from Heinrich Heine University in Dusseldorf, in cooperation with scientists from the Universities of Cologne and Frankfurt, say they have found important evidence. Their study suggests that certain circuits in the brain help determine what function a worker bee performs as it ages.The results, published in the journal Proceedings of the National Academy of Sciences (PNAS), show that changing the activity of certain neurons in the brain can cause older bees to return to tasks that would normally only be done by younger bees.
Bees change their jobs as they age
Unlike humans, honeybees do not have a leader to whom to assign work. However, the colony runs smoothly because worker bees naturally change jobs as they age.Young worker bees spend their time feeding and caring for the queen and developing larvae. As they grow, they help build and guard the cell. At the end of their lives, they leave the hive to collect nectar and pollen.Although worker bees typically follow a job order based on age, scientists have known that the system is flexible. If the colony suddenly loses many young worker bees, some of the older bees can return to nursing duties. Likewise, younger bees may start foraging earlier than usual if more foragers are needed, according to a 2008 study. The new study helps explain how the brain controls these changes.
Scientists knew that an age-dependent pattern existed, but they did not understand how the bee brain controls these changes. The research focused on a gene called doublesex.
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Previous studies by Professor Martin Bye’s team have shown that when this gene was switched off in older worker bees, they began to care for the queen again rather than continuing with the jobs they normally performed at their age. This suggests that the gene may play an important role in controlling working behavior within the colony.Because the gene is only active in certain circuits in the brain, researchers have used it to study how those circuits affect the functions that bees perform. The scientists used a method that allowed them to temporarily reduce the activity of brain circuits associated with the double gene. They did this by activating a neuron-silencing protein after feeding the bees a certain substance.When these brain circuits slowed, the older worker bees began caring for the queen again.
When the circuits were left unchanged, the bees continued their normal age-related work pattern.“The older workers then resumed caring for the queen, which only the younger bees had done,” said Dr. Jana Seiler, lead author of the study, quoted by Science
What the results mean
The researchers say that the study provides evidence that communication between different brain circuits helps determine the tasks that bees perform during their lives. This means that reducing the activity of one set of brain cells appears to allow another set of brain circuits to become active, changing the bee’s behavior. The team believes this helps explain how bee colonies organize work without any central planning.Professor Martin Bye said: “The ability to control the social behavior of bees provides us with new opportunities to explore the fundamentals of innate behavioral diversity and social cooperation. The solution to the mystery of how bees and other animals cooperate so well without a blueprint for action is likely hidden in the neural circuits of the brain.”The researchers say their work provides a better understanding of how the brain controls social behavior in honey bees, and may help scientists study how cooperation evolved in other animals as well.
