March 8, 2012 | 1
After studying hives—both in the wild and in the lab—and analyzing genetic and biochemical profiles of bees’ brains, researchers have found that some bees, like some humans, seem to be programmed to seek out new experiences, or novelty.
Forager bees are in charge of gathering food outside of the hive, but not all of these bees, it seems, are inclined to strike out and go exploring for new flowers. Only a subset of them—some five to 25 percent—actively scout out new pollen sources. The rest of the foragers simply follow these adventurers’ bee dances to find the food. A similar division happens when a group of bees set out in a swarm to start a new hive. In a swarm, less than five percent of foragers acted as nest scouts—independently searching for a suitable new home.
The researchers wanted to see if these scouting groups overlapped, which would indicate an underlying tendency of a subgroup of bees to seek out the new—within the larger category of forager bees. And if some bees are striking out for novel finds in different circumstances, that, they argued, would be evidence that these bees have an essential “personality” difference from their fellow foragers.
To figure out if some bees searched for new food and for new real estate, the researchers first pinpointed the food scouts. Under the cover of night, when bees generally don’t forage, hives were moved to a new location outside of familiar territory. The researchers then singled out bees that served as food scouts—the ones that located flowers and returned first to tell other bees where to find the choicest pollen. Then, to see if the food scouts were also more inclined to hunt out new homes, the researchers watched eight different colonies over two years to see which bees took the lead when swarms broke off to find a new home. It turns out that the nest scouts were more than three times as likely as other foragers to also be food scouts.
The researchers then looked to see whether the food and nest scouting behaviors had a genetic basis. Whole-genome scans on the bees revealed “a large neurogenomic signature for scouting in the bee brain,” they reported in a paper, published online March 8 in Science.
Some genetic differences between scouting and non-scouting brains were predicted. “We expected to find some, but the magnitude of the differences was surprising given that both scouts and non-scouts are foragers,” Gene Robinson, director of the Institute for Genomic Biology at the University of Illinois at Champaign-Urbana and co-author of the new study, said in a prepared statement. There were many minute genetic differences. But one of the biggest finds were distinct differences in 10 genes that help to control catecholamine, glutamate and gamma-aminobutyric acid (GABA) signaling—signatures that have also been linked to novelty-seeking and reward behavior in humans.
To solidify their finding, the researchers tried changing the levels of these signals in scouting and non-scouting bees to see if they indeed affected their behavior. Non-scouting bees got extra glutamate and octopamine, while dopamine—a reward neurotransmitter—was inhibited in scouting bees. With these signals switched, the non-scouting bees became more inclined to go explore, and without dopamine, the scouting bees were less so.
Does this mean that these bees really have individual “personalities”?
Personality can sound like a strong word for any animal research—especially that done in insects. But, Robinson noted, “if you show the same tendency in different contexts, then that can be called a personality trait.” So with the parallels in food and hive scouting bees, he suggests that this novelty-seeking behavior is, indeed, an example of personality.
And that has deeper evolutionary implications. It is possible that insects and vertebrates developed similar signals independently, but a more likely explanation is that “these mechanisms represent part of a basic tool kit that has been used repeatedly in the evolution of behavior,” the researchers wrote in their paper.