Honeybees may seem like nature’s perfect little automatons: organized, efficient, self-sacrificing. But in reality the insects are imperfect individuals. Their dance language is sloppy and imprecise. They lose self-control when they’re hungry. And, a new study has found, worker bees have distinct personalities.
Iowa State University ecologists Alexander Walton and Amy Toth explain that animals need to meet three requirements before you can say they have “personalities.” First, individuals have to behave differently from each other in a way that’s consistent over time. Second, those behavioral differences also have to show up across different contexts. Finally, there should be sets of behaviors that tend to clump together, like personality types.
To look for these features in honeybees, the authors put groups of worker bees into cages. This was an artificial setting, but it let the scientists closely track the behavior of each individual bee (they marked the insects with dabs of colored paint to tell them apart). In a hive, worker bees’ responsibilities change as they age. They transition from indoor tasks—cleaning, building, taking care of young—to outdoor tasks like foraging and guarding the hive. But all the bees in the experimental cages were the same age, so this shouldn’t have affected their behavior.
Every other day, the researchers exposed the bee cages to a series of tests. In one test, they put a slide carrying queen mandibular pheromone into the cage. When a queen bee releases this chemical, it tells workers to groom and feed her. In another test, a slide held alarm pheromone—bees make this chemical when the colony is under attack. And in a third test, the scientists dropped a real live bee into the cage. Since the other bees didn’t know this bee, they would view it as an intruder.
The researchers looked for several reactions among the bees, including touching a slide with their antennae, attacking an intruder bee, or attacking each other. How individual bees responded to each test was consistent from one day to the next, the researchers found. So the bees met the first criterion for personality.
For the second criterion, Walton and Toth looked only at the behaviors that were possible in all three contexts. They found that one behavior in particular was consistent across different contexts. This was “trophallaxis,” or bees sharing their food mouth-to-mouth. Bees that responded to one of the tests by giving some food to their sisters were more likely to respond to the other tests in the same way.
To check the third criterion of personality, the researchers studied bees in an actual hive. This was a little harder to do. But they tried to monitor of a whole range of behaviors in individual bees, including grooming, dancing, guarding, foraging for pollen, and taking care of the queen. They found a handful of behaviors that did group together: some bees were more prone to certain tasks that involved interacting with their sisters, while other bees were more fond of individual tasks.
Overall, honeybees seemed to have “hallmarks of personality,” the authors write. But they think age-related changes in bee duties might ultimately matter more to how a bee spends her time. So, fine—they’re still kind of like robots.
Image: by Brad Smith (via Flickr)