During the tests, groups of young honey bees, which are independently figuring out how to find food, begin to spontaneously sway, but badly.
Swinging matters. A honey bee runs and turns in loops that encode clues that help its colony members fly to the food it has found, sometimes several kilometers away. However, in the five colonies in the new test, there were no older sisters or half-sisters to act as role models for performing the dance moves correctly.
Still, the dancing improved somewhat as the children moved and circled day after day, reports behavioral ecologist James Nye of the University of California, San Diego. But when the bees found clues to obtain distance information, Apis mellifera without role models never matched the timing and encoding in normal colonies, where young bees practiced with older foragers before performing the basic swing themselves.
Thus, juvenile-only colonies show that social learning, or lack thereof, matters for honey bee communication through dance, say Nye and an international team of colleagues at Science March 10. It turns out that bee swaying, a kind of language, is both innate and learned, like a songbird or human communication.
The dance may seem simple in the scheme, but it becomes difficult to perform it in the spaces of the cells. The bees “run forward at more than one body length per second in the pitch black, trying to keep the right angle, surrounded by hundreds of bees swarming them,” Nye says.
Beekeepers and biologists know that some species of bee can learn from others of their kind—some bumblebees have even tried to play soccer. But when it comes to waggle dancing, “I think people assume it’s genetic,” Nye says. This would make this fancy footwork more like the chatty but innate color-changing communication of a cuttlefish, for example. Instead, laboratory experiments with bees show a nonhuman example of “social learning for complex communication,” Nye says.
Testing social learning required some sophisticated beekeeping work. At an apiary research center in Kunming, China, researchers placed thousands of near-adult honeybees (at the so-called purple-eyed pupal stage) in incubators, then collected the new winged adults as they emerged.
These young children got into five strangely populated colonies of newcomers of the same age. Each colony had a queen who laid eggs but did not leave the colony to forage. The food had to come from a young workforce, without the older, experienced foragers buzzing and dancing around the flowers.
During the waggle dance, the forager bees have to master not only the movements, but also the obstacles of the honeycomb dance floor. The cell can be empty. “These are just edges to hold on to… It would be easy to trip over,” Nye says. Unlike commercial hives with manufactured, uniform combs, natural combs are “very irregular,” he says. “They get a little crazy and rough around the edges.”
A honey bee that brings home food to its colony does a wobbly dance, telling its fellow colony members how to find the source. In the center, a bee with a green dot on its back performs its first dance as other bees crowd around. She has already learned to imitate the dances of other experienced foragers, so she makes quite ordinary figure eights. A new study shows that bees that don’t have such mentors can’t dance well.
Dancing on these treacherous surfaces encodes the direction of food at the angle at which the dancer swings across the comb (measured relative to gravity). The length of the swing gives a clue as to how far the gold is.
Unlike the five other colonies in the apiary with a natural mixture, the five shipwrecked colonies were left to figure out the dances on their own. At the beginning of the experiment, the researchers recorded and analyzed the first dances of five bees from each hive.
Even in hives of various ages, the dancers did not always get the perfect angle. The extremes in a series of six runs can differ by a little more than 30 degrees. However, at first there were many more problems with the beehives that suffered death. The angles of two of the five dancers suffering a fall deviated by more than 50 degrees from each other, and one poor bee deviated by more than 60 degrees in six repetitions.
Wobbling dances allow honeybees to share news about where to find food. The honey bee, marked with a purple dot that forms an irregular eight in the center, had no older, experienced foragers to guide it in practice dances. As a result, her first dance is rough and the other bees seem to run into her as much as they follow her. The study, which compared bees with and without dance mentors, shows that this sophisticated communication is a mixture of innate and learned behavior.
As the shipwreck victims gained more experience, they became better. A retest with the same tagged bees a few weeks later, at the end of their lives, found them to spin about as well as the dancers in a regular hive.
What the ship’s victims didn’t change were the dance features that encode distance to food. The researchers set up the hives so that everyone had the same experience covering the distance to the feeder. However, the victim bees continued to dance as if it was further.
They gave more sweeps per run (about five sweeps) than bees from hives of different ages (more than 3.5 sweeps). Youngsters also took longer on each run.
Evidence like this foraging study “is really piling up for the importance of learning (individual or social) in complex bee behavior,” says insect ecophysiologist Tamar Keasar of the University of Haifa in Israel in an email. In her own work, she sees how bees learn to forage from complex flowers. After all, bees aren’t just little automatons with wings.
