The waggle dance in honey bees is only partly based on innate behavior. A study shows that social learning also plays an important role for bees when it comes to correctly coding the direction and distance of a food source. Bees, which have never been able to observe experienced individuals dancing their waggles, also dance themselves, but transmit the signals imprecisely and incorrectly. Although the dances become more precise with experience, some mistakes remain throughout the bee’s life.
In order to communicate information about the exact location and quality of a food source to swarm members, honey bees perform complex signaling movements. During the so-called waggle dance, they crawl at high speed in eight-shaped loops in the beehive and wiggle their abdomens as they do so. The length and angle of the loops encode the flight distance and direction to the target. Different bee species and even different colonies of the same species show slightly different patterns in different regions, so they obviously have dialects when communicating.
Young bees without role models
So far it was unclear whether the waggle dance is a completely innate behavior or whether social learning also plays a role, similar to other complex forms of communication. If the behavior were entirely innate, it should make no difference whether a young honey bee could observe other bees dancing before their first waggle dance. To test this, a research team led by Shihao Dong from the Chinese Academy of Sciences in Yunnan examined bee colonies consisting exclusively of newly hatched animals.
“Usually, young foragers have the opportunity to learn from older individuals,” Dong and his team explain. “At the age of eight days, they begin to follow experienced waggle dancers, and at twelve days they start dancing themselves.” In the bee colonies created for the experiment, however, the young bees had no role models to follow. Nevertheless, they too began to dance – in accordance with the realization that the basic disposition for the waggle dance is innate.
Lifetime Mistakes
But while young bees from control colonies, which were able to orientate themselves on older animals, carried out the correct movements from the start, the exemplary young bees had problems with this: “Bees that did not have the opportunity to follow dancers before they danced for the first time produced significantly more disordered dances with larger angular divergences and incorrectly coded the distance,” reports the research team.
Would these mistakes even out over the course of the bee’s life as individuals gained more experience? To find out, Dong and his colleagues observed the bees again 20 days later, towards the end of their approximately six-week lifespan. “When the same bees were older and had experience dancing and following dancers, they significantly reduced directional errors and produced more ordered dances. However, they were never able to perform normal distance encoding,” Dong reports. All their lives, these bees reported too great a distance to the food source.
Critical phase of social learning
Thus, although the bees partially compensated for the deficits over time through experience, they retained certain faults. From the researchers’ point of view, this indicates that there is a critical phase at the beginning of the bee’s life, in which the subtleties of the waggle dance are acquired through social learning. During this time, the ethnic-specific dialect is also taught. Young bees, lacking this opportunity, developed a kind of faulty dialect of their own, which they retained throughout their lives.
But why do bees use social learning to refine their innate waggle dance behavior in the first place? “Learning is a useful way to adapt behaviors to local conditions,” explains the research team. “We suspect that the unique topology of each bee colony’s dance floor makes it beneficial for novice dancers to learn from more experienced dancers. Another possibility is that experienced dancers relay distance information to fellow flocks based on local optic flow.”
Pesticide threat?
In future studies, the team would like to investigate in more detail what role the environment plays in the development of bee dialects. The question of the extent to which external threats, such as pesticides, disrupt language acquisition in social insects is also an open question. “We know that bees are very intelligent and can do remarkable things,” says co-author James Nieh of the University of California at San Diego. “Several publications and studies have shown that pesticides can impair the cognitive abilities and learning ability of honey bees. Therefore, pesticides could impair their ability to learn how to communicate and potentially even change the way that communication is passed on to the next generation of bees in a colony.”
Source: Shihao Dong (Chinese Academy of Sciences, Kunming, Yunnan, China) et al., Science, doi: 10.1126/science.ade1702