Some fruit flies seem to enjoy whizzing around on a carousel in what may be a form of play.
Many animals, such as dogs and gorillas, appear to play regularly, but it is unclear how common such behaviour is in insects and other invertebrates. Last year, researchers found that bumblebees roll wooden balls around in the first evidence of insect play.
and at the University of Leipzig in Germany have now found that fruit flies (Drosophila melanogaster) appear to engage in play too.
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The researchers built several small arenas with access to a spinning carousel and some food. They placed 112 flies in the arenas, with each one housing one fly at a time for three to four days each, to see how they interacted with the environment. Another 194 flies were placed in the same environment, but with a stationary carousel, as a comparison group.
Flies that had access to the spinning carousel spent upwards of 5 minutes on it at a time 鈥� significantly more than those for whom the carousel didn鈥檛 move. Many of the flies visited the spinning carousel several times over the course of the experiment.
鈥淲e were all astonished,鈥� says Huetteroth. 鈥淢y expectation was that the flies would completely avoid it and wouldn鈥檛 like it at all.鈥�
To be considered play-like behaviour, an activity must have no immediate relevance for survival, and it must be voluntary and intentional. These findings strongly suggest that fruit flies engage in play, says Huetteroth, expanding what we currently understand about their biology.
Intriguingly, the team found that some flies in the spinning carousel group seemed to seek it out much more than others, while some flies avoided the platform altogether.
鈥淭he study is quite well designed to make a convincing case that flies will voluntarily seek the opportunity to experience whizzing around,鈥� says at the University of Lethbridge in Canada. 鈥淲hat the study does not explain is why some flies seem to like this experience and some don鈥檛.鈥�
BioRxiv
