Photo credit: Screen capture from PLOS Media

Study demonstrates how ‘unusual’ skills can spread through a bumblebee colony.

A new study published in PLOS Biology reveals that bumblebees can be trained to pull a string to access a reward, and other colony members can learn this skill simply by watching the trained bees do it.

To test the bumblebees’ cognitive skills, Lars Chittka from Queen Mary University of London, UK, and colleagues poured sugar water onto artificial flowers, which were attached to strings and placed under Plexiglas. They then trained bees to tug on the string to access the sugar water — an “unusual” task that does not mimic any behavior the bees would normally perform in the wild.

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"What I like about the work, in addition to the experimental and intellectual challenges and insights, is the sheer absurdity of seeing bees solving a string-pulling puzzle,” said Chittka in a press release. “When lead author Sylvain Alem first showed me a bee successfully pulling on the string, I just couldn't believe what I was seeing. And even now, looking at the videos still makes me laugh."

When untrained bees were faced with the task, they rarely learned to pull the string on their own. But after being placed in transparent cages that allowed them to observe a demonstration by trained bees, 60 percent of the untrained bees were able to solve the problem.

Although over a century of behavioral research has shown that primates, cetaceans, birds, and fish can acquire new skills simply by watching others, until now, few studies have tested this ability in insects.

To see whether the string pulling behavior would spread in a natural social situation, the researchers placed a single trained bee in each of three colonies of untrained bees. They write in their paper, “once one bee knew how to string pull, over time, most of the foraging bees learned from the initially trained bee or from bees who had learned from the trained bee, even after the initial demonstrator was no longer available.”

The ability of animals with relatively small brains to learn a complex task, and culturally spread that learned knowledge to others, makes Chittka question, "How much brainpower is actually required for any one task — how many neurons, how many sequential and parallel neural processing stages?"

"In that view,” he says, “the single task that actually requires a big brain has not been discovered yet, and indeed there is more and more evidence, both from experiments on small-brained insects and computational neuroscience, that small circuits can deal with exceptionally complex challenges.”

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