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Do Bees Have Fun Too? Playful Behavior in Bees Identified for the First Time


Animal play is a widely observed phenomenon, but examples of it are most prevalent in mammals and birds. Here, the researchers show that ball-rolling behavior by bees meets the criteria for play established by Burghardt (2005): it is a behavior with no apparent function at the time, performed spontaneously and repeated for pleasure. This is one of the first studies to document play in invertebrates, raising questions about the cognitive and emotional capacities of bees.


Play is not unique to humans, but a phenomenon present in many animal species, as first observed in the 19th century by Groos (1898). Studies indicate that play plays a crucial role in the healthy development of cognitive and motor skills.


These skills, in turn, can be useful in essential tasks, such as finding food. Furthermore, play is seen as a fundamental element of animal well-being. The clearest examples of play have been documented in mammals and birds with large brains. However, systematic research on play in other types of animals is scarce. This is partly because it is challenging to define and study play in such diverse species.


To facilitate the investigation of this behavior in animals, Burghardt (2005) proposed five main criteria that help identify play.

First, play is a behavior that does not have an obvious or adaptive function at the time it occurs (Criterion 1). For example, behavior performed solely to obtain food, shelter, or mates is not classified as play.


Second, it is voluntary and spontaneous, and is performed because it is rewarding in itself, without depending on an additional reward (Criterion 2).


Third, play is distinct from normal functional behaviors in its form. That is, the movements performed are distinct from those used in activities such as foraging or reproduction (Criterion 3).


Fourth, play is repetitive but does not follow a rigid or automatic pattern (Criterion 4), which differentiates it from tics or stereotypic behaviors. Finally, play only occurs when the animal is in a relaxed state.


Stress can temporarily prevent play, although in some situations play can help reduce stress (Criterion 5). This last criterion helps distinguish play from stress-induced behaviors such as circling, a common behavior in caged animals.


Play can be divided into three main categories: social, locomotor, and object play. Social play involves playful interactions between animals, such as mock fights between young of the same species.

Locomotor play involves intense movements, such as running or jumping, without a specific goal, just for the pleasure of movement.


Object play involves manipulating inanimate objects, such as balls or twigs. Although less studied, there is evidence of social play even in insects, such as ants (Formica rufa) and young wasps (Polistes dominulus), which exhibit behaviors similar to play fighting.

The study, conducted by researchers at Queen Mary University of London, UK, which we discuss here, focuses on object play in bees.


Previously, this group of researchers used another approach, training bees to roll a ball toward a goal, rewarding them with sugar water. Some bees were able to do this without any demonstration. Other bees observed their companions doing this and then figured out even faster ways to move the ball.

But this reward system did not characterize or differentiate whether the bees played for fun or for reward.


In this new study, across three different experiments, they examined whether ball-rolling behavior by bees met established criteria for play and how ball-rolling resembled object play in other animals.

Experimental setup. Aerial view of the section of the experimental arena containing the foraging area and the object area. A nest box containing a bee colony was connected to the arena via a plastic tunnel. The tunnel led to an unobstructed path in the object area with colored objects on the sides of the path: nine moving balls on the right and nine non-moving balls on the left. The path led to the foraging area that contained ad libitum 30% sucrose (S) and ground pollen (P). Sucrose was replenished externally via a tube. The location of the sucrose and pollen was alternated each day to prevent the bees from developing a lateral bias.


Experiment 1: Do bees engage in object manipulation as play?


A total of 910 ball-rolling actions by 45 bees were recorded. Individual bees rolled balls between 1 and 44 times on an experimental day and between 1 and 117 times over the entire duration of the experiment.


Most bees (37/45) rolled balls for at least one additional day after feeding in the foraging area, and 29 bees for at least two additional days.


The results showed that before experiencing ball rolling, bees showed no significant preference between exploring the area with moving balls or the area with stationary balls. However, after the first experience of rolling a ball, they demonstrated a strong preference for the area with moving balls.


The behavior was repetitive, and bees continued to interact with the balls on subsequent days. This pattern indicates that the behavior was not motivated by an immediate need, but possibly by the pleasure associated with the activity.


Interestingly, there was no preference for specific ball colors, suggesting that the interaction was not related to an attraction to a particular color.

Video S1. An example of a ball rolling by a bee at speed × 0.5. The bee approaches a colored wooden ball while facing it, touches the ball with its front legs, holds the ball using all its legs, rolls the ball, detaches itself and leaves the ball. The bee approaches a second ball, rolls it and detaches itself.


Experiment 2: Does age influence engagement in ball rolling?


In this experiment, we investigated whether the age of bees influenced their propensity to roll balls. Younger bees (up to 3 days old) exhibited significantly more ball rolling actions (average of 11 times per day) than older bees (at least 10 days old, with an average of 4 times per day).


These results indicate that the behavior is age-related, being more frequent in young bees. This is consistent with observations in mammals and other animals, in which play tends to be more intense in early stages of development.


Experiment 3: Can ball-rolling behavior act as an unconditioned stimulus?


To investigate whether ball-rolling is inherently rewarding, bees were given access to two colored chambers: one containing moving balls and one containing no objects.


During a subsequent test in which both chambers were available, the bees showed a preference for the chamber associated with the presence of the balls. This suggests that the ball-rolling activity is rewarding in its own right, independent of other external rewards.

Animal play is a widely observed phenomenon, but examples of it are most prevalent in mammals and birds. Here, the researchers show that the ball-rolling behavior of bees meets the criteria for play established by Burghardt (2005): it is a behavior with no apparent function at the time, performed spontaneously and repeated for pleasure.


Furthermore, the results revealed that age influenced the frequency of play, with young bees being more likely to interact with objects, a pattern similar to that observed in other animal species.


Finally, the behavior proved to be rewarding, as demonstrated by the bees’ preference for the chamber associated with the activity.


This is one of the first studies to document play in invertebrates, raising questions about the cognitive and emotional capacities of bees. It reinforces the idea that even insects have complex behaviors, which may be associated with skill development and intrinsic pleasure.



READ MORE:



Do bumble bees play?

Hiruni Samadi Galpayage Dona, Cwyn Solvi, Amelia Kowalewska, Kaarle Mäkelä, HaDi MaBouDi, and Lars Chittka

Animal Behaviour. Volume 194, December 2022, Pages 239-251


Abstract:


A variety of animals have been found to interact with and manipulate inanimate objects ‘just for fun’, that is, to play. Most clear examples of object play come from mammals and birds. However, whether insects interact with inanimate objects as a form of play has never been systematically examined. Here, we show that rolling of wooden balls by bumble beesBombus terrestris, fulfils behavioural criteria for animal play and is akin to play in other animals. We found that ball rolling (1) did not contribute to immediate survival strategies, (2) was intrinsically rewarding, (3) differed from functional behaviour in form, (4) was repeated but not stereotyped, and (5) was initiated under stress-free conditions. Through the design of the experiment and with the support of behavioural observations, we excluded the possibilities that ball rolling was driven by exploration for food, clutter clearing or mating. Similar to vertebrate play, we also found age and sex differences for ball rolling by bumble bees: younger bees rolled more balls than older bees and male bees rolled individual balls for longer durations than females. We explicitly show that ball rolling is itself a rewarding activity. After being trained to find freely movable balls in one of two differently coloured chambers, bees showed a preference for the colour of the chamber where they had rolled balls. Our results contribute to the question of sentience in insects and lend further support for the existence of positive affective states in these animals.

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