In a castaway test setup, groups of young honey bees figuring out how to forage on their own start spontaneously — but poorly.
Wobble counts. A honey bee’s hopping legs and turning loops encode cues that help its colonymates fly to food it has found, sometimes miles away. However, five colonies in the new test did not have older sisters or half-sisters as role models for proper dance moves.
Still, in some ways, the dances improved as the youth wobbled and looped day by day, reports behavioral ecologist James Nieh of the University of California, San Diego. But if you wiggle the hints for distance information, Apis mellifera without role models never matched the timing and coding in normal colonies where young bees practiced with older foragers before doing the main wiggle themselves.
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The squab-only colonies thus demonstrate that social learning, or the lack thereof, is important for communication through dance among honey bees, say Nieh and an international team of colleagues in the March 10 issue Science. Bee-Wiggle Dance, a type of language, turns out to be innate and learned, like songbird or human communication.
The dance may appear simple on a diagram, but it becomes difficult to perform on expanses of honeycomb cells. Bees “run forward in the dark at over a body length per second, trying to keep the right angle, surrounded by hundreds of bees crowding around them,” says Nieh.
Beekeepers and biologists know that some bee species can learn from others of their kind – some bumblebees have even tried soccer (SN: 02/23/17). But when it comes to wobble dancing, “I think people have assumed it’s genetic,” says Nieh. That would make that fancy footwork, for example, more like the garrulous but innate color-changing communication of octopuses. Instead, the laboratory experiments with shipwrecked people show a non-human example of “social learning for sophisticated communication,” says Nieh.
Testing for social learning required laborious beekeeping. At a beekeeping research center in Kunming, China, researchers placed thousands of near-mature honey bees (in the so-called purple-eyed pupal stage) in incubators, then collected the brand-new winged adults as they emerged.
These youngsters went to five strangely populated colonies of worker novices of the same age. Each colony got a queen who laid eggs but did not leave the colony to forage. The food had to come from the young workforce without older, experienced choppers swarming in and flower locations dancing.
In the wobble dance, forager bees not only have to master the movements, but also the obstacles of the honeycomb dance floor. A cell can be empty. “It’s only the fringes to hold on to… You could easily stumble,” says Nieh. Unlike commercial hives with manufactured unitary honeycomb cells, natural honeycomb is “very irregular,” he says. “They get a little crazy and rough around the edges.”
Dances on these treacherous surfaces encode the direction of eating in the angle at which a dancer wiggles over the ridge (measured relative to gravity). The duration of the wobble gives an indication of how far away the gold mine is.
The five colonies of castaways, unlike five other colonies in the apiary, had to dance alone with a natural mixture. At the beginning of the experiments, the researchers drew and analyzed the first dances of five bees from each hive.
Even in the mixed-age hives, the dancers didn’t get the perfect angle every time. The extremes in a set of six waggle runs can differ by a little over 30 degrees. The castaways, however, had many more problems at first. The angles of two of the five castaways deviated by more than 50 degrees, and one poor bee deviated by more than 60 degrees in six repetitions.
However, as the castaways gained experience, they got better. When the test was repeated a few weeks later towards the end of their lives with the same tagged bees, they found they were fishing around just like dancers in a normal hive.
What the shipwrecked did not change significantly were dance characteristics that encode distance from eating. The researchers set up the hives so that everyone would have the same experience walking the distance to a feeding station. But castaways danced on as if they were on.
They gave more trunk wobbles per wobble run (closer to five wobbles) than bees from mixed-age hives (closer to 3.5 wobbles). The youngsters also needed longer for each run.
Evidence like this foraging study “is actually accumulating for the importance of learning (whether individual or social) in the complex behavior of bees,” says insect ecophysiologist Tamar Keasar of the University of Haifa in Israel in an email. In her own work, she sees bees learning to extract food from intricate flowers. After all, bees aren’t just little automatons with wings.