Bees like to roll small wooden balls as a form of play, study finds

There’s rarely time to write about every cool science story that comes our way. That’s why we’re once again posting a special Twelve Days of Christmas series of posts this year, highlighting one science story every day from December 25 through January 5 that has fallen through the cracks in 2020. Today: Scientists Caught Bees Rolling Wooden Balls , just for fun, on video, with additional evidence that bees can experience positive ‘feelings’.

Many animals are known to play, mostly large-brained mammals (like humans) and birds. Now scientists think they’ve observed real play behavior in bees, which were filmed rolling small colored wooden balls, according to an October paper published in the journal Animal Behavior.

“This research strongly indicates that insect minds are much more advanced than we can imagine,” said study co-author Lars Chittka of Queen Mary University of London and author of a recent book, The ghost of a bee. “There are many animals that play just for fun, but most examples come from young mammals and birds.”

According to the authors, gaming behavior is generally divided into three broad categories. Social play involves playful interactions between animals, usually young animals engaged in play-fighting. For example, there is anecdotal evidence from previous studies (one dating back to 1820) for social play between ants and young wasps. Locomotor play involves running, jumping, or similar intense and sustained movements not associated with any particular goal. And when playing with objects, an object is manipulated like a toy.

Chittka’s group conducted a previous study in 2017 in which they showed that bees can be trained to roll small wooden balls in order to receive a reward. But they also noted instances where the bees chose to roll the balls even when there was no obvious reward or benefit. The balls were placed in a tunnel that connected the hive to the experimental arena where the food was. Several bees walked over the balls or stopped to roll them on their way back and forth from the food. Chittka et al. wondered if this could be real gaming behavior and decided to investigate further.

It is not easy to design an experiment that conclusively demonstrates that bees (or other insects or animals) specifically engage in play behavior. It’s not like you can just ask the bees if they’re having fun. Five basic criteria must be met.

First, the behavior should not be performed to obtain food, attract a mate, or seek shelter. Second, the play behavior must be “voluntary, spontaneous, and rewarding in itself,” rather than being associated with some kind of reward. Third, the motor actions for play behavior must be different from the actions performed when searching for food or attempting to mate. Fourth, the play behavior is repeated but not stereotyped, to distinguish between a one-off event and a usual tic. Finally, play should be initiated when the subject is relaxed, to distinguish it from stress-related behaviors such as pacing or walking, both of which are commonly observed in caged animals.

For these new experiments, Chittka et al. followed a similar arrangement. They placed 45 bees in the arena and let them choose to walk in a straight line to a foraging area of ​​food, or wander off that path through an area of ​​colored wooden balls. Even when they finished eating, most bees (37) chose to roll balls for at least one extra day after, with 29 rolling balls for two extra days after eating. Individual bees rolled balls between 1 and 117 times over the duration of the experiment, with the latter number suggesting that at least some of the bees found the activity rewarding.

In a second experiment to help determine if this qualified as a game, another 42 bees were given access to two color-coded chambers, one of which was empty while the other always contained wooden balls. Then the balls were removed and the bees were allowed to choose which room to spend time in. They showed a strong preference for the room with a color previously associated with the wooden balls. A third experiment revealed that younger bees rolled balls more often than older bees, and male bees rolled balls for a longer duration than female bees.

Overall, the authors state that the behavior of the bees in their experiments met the five basic criteria for play. “It’s certainly amazing, sometimes amusing, to see bumblebees demonstrate something like play,” said study co-author Samadi Galpayage, a graduate student in Chittka’s lab. “They approach and manipulate these ‘toys’ again and again. It shows once again that despite their small size and small brains, they are more than little robotic creatures. They can even experience some kind of positive emotional states even if they are rudimentary, like other larger fluffy or less fluffy animals.

DOI: Animal Behavior, 2022. 10.1016/j.anbehav.2022.08.013 (About DOIs).