Read our COVID-19 research and news.

Bumble bees are surprisingly innovative

Bumble bees may have small brains, but that doesn’t mean they’re not inventive. A new study shows that the insects can innovate to solve complex problems, quickly figuring out a better way to get a sugar reward. Such mental flexibility may help bees overcome human-caused changes to their environment.

“It’s a cool study, and both the authors and the bees deserve credit for their innovativeness,” says Dhruba Naug, a behavioral ecologist at Colorado State University in Fort Collins.

Bumble bees have already proven themselves remarkable animals. They possess complex navigational skills, rudimentary culture, and emotions. They can even use tools: Scientists have shown that the insects can learn to pull a string—and so get a sugary reward—by watching another bee perform the task. Although bees don’t pull strings in the wild, they do sometimes pull or push aside flower petals and parts that may resemble strings.

“That made us wonder if bees could learn to do something with an object they had never encountered in their evolutionary history,” says Olli Loukola, a behavioral ecologist at Queen Mary University of London, an author on the string work.

So in the new study, Loukola and colleagues made the bees forage for sugar water by moving a small, yellow ball to a specific target (as in the video above)—something far removed from what the insects do in the wild. The scientists first trained the bees to know that the ball had to be in a target location in order to yield sugar water. Then each insect was shown three yellow balls placed at varying distances from the target. Some bees watched a previously trained bee move the farthest ball to the target and get a reward. Other bees watched a “ghost”—a magnet beneath the platform—move the farthest ball. And a third group didn’t see a demonstration; they simply found the ball already at the target with the reward.

In separate tests, each bee was subsequently challenged to move one of the three balls to the target within five minutes. The 10 bumble bees that watched a sister perform the task were the most successful, the scientists report today in Science. They also solved the task faster than those that watched the ghost or didn’t see a demonstration. Some of the latter bees solved the task entirely on their own.

The bees quickly figured out a better way to move the ball, too. Although those that watched the demonstrator initially pushed the ball to the target, in subsequent trials, they walked backward and pulled the ball—an unexpected and innovative change, the scientists say.

The bees also displayed inventiveness when deciding which ball to move. Although the demonstrator bees always moved the farthest ball (because the others were glued in place), most of the observer bees chose instead to move the ball that was closest to the target. When the researchers replaced the yellow ball that was closest to the target with a black ball, most of the bees moved it for the reward—showing that they understood the general principle of the task: Move a ball to the center, not move only a yellow ball.

“These bees solved the problem more effectively,” and showed that they could “generalize the solution to new situations,” says Anne Leonard, a behavioral ecologist at the University of Nevada in Reno, who was not involved in the study.

This flexibility could help bumble bees in the wild, which face widespread population declines. “It suggests that bees may be able to respond quickly to novel problems that arise in their environment,” such as the introduction of new flowering plants and the loss of familiar ones, says Daniel Papaj, an evolutionary biologist at the University of Arizona in Tucson.

Most importantly for the study’s researchers, “It puts the final nail in the coffin of the idea that small brains constrain insects’” cognitive abilities, says co-author Lars Chittka, a behavioral ecologist also at Queen Mary University of London. There’s more going on beneath that exoskeleton than we think.