Honeybee colonies work in an organised way even though no bee tells the others what to do. Young bees look after the queen and baby bees, older ones build and guard the hive, and the oldest workers fly out to collect food. Scientists have long known this pattern, but they did not know how the bees’ brains controlled these changes.Researchers from Heinrich Heine University Dusseldorf, together with scientists from the universities of Cologne and Frankfurt, say they have found an important clue. Their study suggests that specific brain circuits help decide which job a worker bee performs as it grows older.The findings, published in the Proceedings of the National Academy of Sciences (PNAS), Science X reported, show that changing the activity of certain nerve cells in the brain can make older bees return to tasks that are usually done only by younger bees.
Bees change jobs with age
Unlike people, honeybees do not have a leader assigning work. Yet the colony functions smoothly because worker bees naturally change jobs as they age.Young worker bees spend their time feeding and caring for the queen and the developing larvae. As they grow older, they help build the hive and guard it. Towards the end of their lives, they leave the hive to collect nectar and pollen.Although worker bees usually follow an age-based order of jobs, scientists have known that the system is flexible. If a colony suddenly loses many young worker bees, some older bees can return to nursing duties. Likewise, younger bees may begin foraging earlier than usual if more food collectors are needed, according to a 2008 study. The new study helps explain how the brain may control these changes.Scientists knew that the age-based pattern existed, but they did not understand how the bee’s brain controlled these changes. The research focused on a gene called doublesex.
Earlier studies by Professor Martin Beye’s team had shown that when this gene was switched off in older worker bees, they began caring for the queen again instead of continuing with the jobs normally done at their age. This suggested that the gene might play an important role in controlling work behaviour inside the colony.Because the gene is active only in certain brain circuits, the researchers used it to study how those circuits influence the jobs bees perform. The scientists used a method that allowed them to temporarily reduce the activity of the brain circuits linked to the doublesexgene. They did this by activating a neuron-silencing protein after feeding the bees a specific substance.When these brain circuits were slowed down, the older worker bees started caring for the queen again. When the circuits were left unchanged, the bees continued their normal age-related pattern of work.“The older worker bees then resumed caring for the queen, which only younger bees would otherwise do. When the circuits were not inhibited, the bees exhibited their normal, age-dependent behavior. In this way, we were able to control which tasks the worker bees performed,” lead author Dr Jana Seiler said, Science X quoted.
What findings mean
The researchers say the study provides evidence that communication between different brain circuits helps determine which tasks bees perform during their lives. It means reducing the activity of one set of brain cells appears to allow another set of brain circuits to become active, changing the bee’s behaviour. The team believes this helps explain how bee colonies organise work without any central planning.Professor Martin Beye said, “The ability to control the social behavior of bees offers us new opportunities to explore the fundamentals of innate behavioral diversity and social cooperation. The solution to the secret of how bees and other animals cooperate so well without a blueprint for work is likely hidden in the brain’s neural circuits.”The researchers say their work offers a better understanding of how the brain controls social behaviour in honeybees and also may help scientists study how cooperation develops in other animals as well.
