Bee sisters are genetically closer than human sisters, so it’s easy to assume this is why they recognise each other.
However, new research led by Cassondra Vernier from Washington University, US, suggests it’s actually shared gut microbiome characteristics that have the real influence.
“What we show is that it is genetic, but it’s the genetics of the bacteria,” says Yehuda Ben-Shahar, corresponding author of the team’s paper in the journal Science Advances.
Actual recognition is due to pheromones on the skin. These are different between colonies and this helps bees recognise nestmates and allow them back into the hive after work – and keep out invaders.
The new study found that these pheromones are caused, at least in part, by shared gut microbiota instead of bee genetics, which is a new concept in how bees socialise.
“Different colonies do in fact have colony-specific microbiomes, which has never been shown before,” says Vernier. “Bees are constantly sharing food with one another – and exchanging this microbiome just within their colony”.
The microbiome is extremely important in health and digestion, but it now seems it is also important in socialisation. As Ben-Shahar puts it: “Their ability to say ‘you belong to this group’ basically depends on getting the right bacteria at the right time. Otherwise, they are blind to it.”
The team first determined that bees from different colonies had different gut microbiomes by sequencing RNA from the gut. They then took baby bees from different colonies and raised them in a new colony. They found that these bees developed a similar gut profile to their hosts, instead of their original colony sisters.
When the researchers altered the gut microbiome of their bees, the sisters could not properly recognise each other anymore and started to think other bees with the same gut microbes were sisters instead.
“The importance of this paper is that it’s one of the first papers that actually shows that the microbiome is involved in the basic social biology of honeybees – and not just affecting their health,” Verner says.
Dr Deborah Devis is a science journalist at The Royal Institution of Australia.
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