Bumblebees display flexible problem-solving

(CN) — Bumblebees may be capable of a level of problem-solving once thought to be reserved for animals with much larger brains.

Researchers found that the insects could use a movable ball to reach a reward without being trained on the task, suggesting they can solve unfamiliar challenges and work toward a goal rather than just respond to visual cues. The findings, published Thursday in the journal Science, add to growing evidence that sophisticated decision-making is not limited to animals with large brains.

Previous studies have shown that some birds and primates can use tools or objects to solve problems. Whether invertebrates could do the same without explicit training has remained less clear.

To test that question, researchers placed bumblebees into an area and familiarized them with two objects: a blue ring that represented a flower and a movable Styrofoam ball. The insects learned that the flower was associated with a sugar reward and that the ball could be pushed around the arena.

The bees were never trained to combine those experiences. However, when presented with the challenge, many rolled the ball beneath the flower and used it as a platform to reach the reward.

“What surprised me most was the high success rate,” lead author Olli Loukola said in an email. “Before running the experiments, I expected perhaps 15–20% of the bees to solve the task. Instead, more than 70% succeeded, which was far beyond my expectations. The fact that so many individuals independently arrived at the solution suggests that this ability may be more widespread in bumblebees than we had anticipated.”

Bees that had prior experience with both the flower and the ball were more likely to succeed than bees that had only been exposed to one of the objects or neither. This indicates the insects were drawing on previous experiences rather than stumbling onto the solution by chance.

The research team then made the task more difficult by hiding the flower behind barriers. Even without seeing the target, many bees still moved the ball to the correct location.

Most successful bees also rolled the ball directly to the right spot without first testing incorrect locations, suggesting their behavior was not simply trial and error.

“This result suggests that the bees were not simply reacting to the sight of the flower or moving the ball because the reward appeared to be getting closer,” said Loukola, who is a behavioral ecologist at Finland’s University of Oulu and University of Turku. “Even when the flower was hidden, they could still move the ball to the correct location. This indicates that they understood what needed to be done to solve the task and were working toward a goal rather than responding only to immediate visual cues.”

Some bees even rolled the ball when no reward was present, further suggesting the behavior was not solely driven by immediate reinforcement.

Researchers say the study adds to a growing body of evidence that insects can solve unfamiliar problems in ways that go beyond simple stimulus-response behaviors.

“Rather than relying solely on simple stimulus-response rules, bumblebees appear capable of generating effective solutions to unfamiliar challenges,” Loukola said. “While we should be cautious about comparing insect cognition directly with that of vertebrates, the findings show that sophisticated decision-making can emerge even in animals with very small brains.”

Further work is needed to better understand the decision-making processes behind the behavior and whether similar abilities exist in other insect species.

“Sometimes the most interesting discoveries can come from relatively simple experiments if the right question is being asked,” Loukola said.