Bumblebees at Play
Reading Time: 4 minutes
Play is one of the most enchanting and mysterious behaviors animals exhibit.
Play is crucial to proper development in many species. Through play, animals develop their cognitive and motor abilities. They figure out their environment and social standing. They figure out weaknesses in prey and locations of edible vegetation. In short, play provides endless learning opportunities for youngsters.
Or so we always thought. Play does all these things, but ethologists are discovering play is more complex and obvious than once thought. Play is energetically costly and potentially dangerous (as any sledding child can testify). Nor is play universal across the animal kingdom, which deepens the mystery of its purpose.
Additionally, playful behavior can extend well into adulthood. The benefits of play have been difficult to quantify scientifically. As one writer said, “Some of the most obvious explanations haven’t held up to scientific scrutiny.”
So play remains, to a large degree, an enchanting mystery. Yet it indisputably happens.
To be defined as “play,” an animal’s behavior must fulfill five criteria:
• The behavior does not contribute to survival (it is not done to obtain food, mates, or shelter).
• It is intrinsically rewarding, meaning it is voluntary, spontaneous, or rewarding in and of itself (since it’s not associated with a reward).
• It differs from functional behavior (the motor actions for the behavior are different from those used, for example, when searching for food or attempting to mate).
• It is repeated but not stereotyped, i.e., neither a one-off chance occurrence nor a habitual tick.
• It is initiated under stress-free conditions, when the animal is relaxed (which distinguishes it from functionless behaviors induced by stress, such as pacing or rocking).
There are three types of play behavior: social, locomotor, and object. Social play consists of interactions between cohorts (usually juveniles), such as play fighting. Locomotor play involves sustained movement, such as running or jumping, without apparent need. Object play involves manipulating inanimate objects (toddlers playing with blocks, for example).
The most obvious examples of play come from large-brained mammals and birds, mainly because defining and investigating play behavior across other animals, primarily invertebrates, is challenging (how can you tell if crabs or sea cucumbers are playing?). But play behavior in insects? With their impossibly small brains, that’s a startling concept.
The idea that insects play has often aroused skepticism. Yet certain behaviors among the Hymenoptera (bees, wasps, hornets, etc.) cannot be described in any other light except playful. Young adult paper wasps, for example, exhibit play-like behavior in an apparent quest for social dominance.
But recent behavior observed in lab-kept bumblebees at the Queen Mary University of London may have blown the whole thing out of the water.
When bumblebees were given small wooden balls, they romped with them. There’s no other way to describe it. They grabbed the balls, rolled around with them, and went back for more. Lots more.
These lab-kept bumblebees were given wooden balls in the first place to see if they could learn complex behaviors by training the bees to move the balls to specific locations in exchange for a sugary reward. But the bumblebees went out of their way to roll the balls around — repeatedly — despite having no apparent incentive (such as food) to do so. They just seemed to be having, well, a ball with the balls.
The balls were 15 mm in diameter. Of the 18 balls used in the experiment, 12 were spraypainted yellow or purple, while the remaining six were left in their original wooden color. All the balls were plastic-coated to enable cleaning with water and 70% ethanol, to remove any scent cues that may have been left by the bees each day.
Initially, the bumblebees were trained to roll the balls to gain a reward, but a funny thing happened on the way to the laboratory. The bees would often roll the balls for no apparent reason. Between experiments, balls were placed in a tunnel connecting the hive to the chamber with food. There was plenty of space for the bees to walk to the food without having to touch the balls, yet they deliberately walked over and rolled around with the balls while on their way to and from the food chamber.
Some of the bumblebees rolled the balls around just once or twice in the experiment, and others romped with them up to 117 times. Younger bees rolled the balls more than older bees, and adult males rolled the balls for longer than females. In short, the bumblebees couldn’t seem to get enough of the wooden balls.
The play behavior was an unexpected discovery the researchers did not anticipate, and they promptly set up alternate experiments to test their theory that the bees were playing. Based on the criteria listed above, there is no other explanation.
The implications are enormous. One researcher wrote, “It is certainly mind-blowing, at times amusing, to watch bumblebees show something like play. It shows, once more, that despite their tiny size and tiny brains, they are more than small robotic beings.”
What purpose could play behavior have for bumblebees? Could it improve their motor coordination when extracting nectar and pollen from flowers? Is object manipulation an essential skill for their survival? We don’t know.
Remember, these bumblebees were originally being studied to see if they could be trained to score goals by rolling a ball to targets in exchange for a sugary food reward. (The answer: Yes). This, by itself, implies an amazing little insect brain. However, this behavior indicates that the brains of bumblebees — less than two cubic millimeters in volume — are more complex and sophisticated than previously thought. It even implies a level of sentience (consciousness) and the possession of emotions.
Whatever the elusive explanation for the behavior of the bumblebees with the wooden balls, I think we can all agree on one thing: It’s just about the cutest thing you’ll ever see.
PATRICE LEWIS is a wife, mother, homesteader, homeschooler, author, blogger, columnist, and speaker. An advocate of simple living and self-sufficiency, she has practiced and written about self-reliance and preparedness for almost 30 years. She is experienced in homestead animal husbandry and smallscale dairy production, food preservation and canning, country relocation, home-based businesses, homeschooling, personal money management, and food self-sufficiency. Follow her website www.patricelewis.com or blog www.rural-revolution.com.
Originally published in the May/June 2023 issue of Countryside and Small Stock Journal and regularly vetted for accuracy.
