How does the memory of bumblebees work?

A new study led by the Queen Mary University of London (QMUL) has found that bumblebees do not seem able to keep memories for how sweet a particular flower was, but instead only remember if it was sweeter than other flowers.

The researchers first trained bumblebees on two flowers, making them learn that one flower was sweeter than the other. Later on, they also learned that a third flower was sweeter than a fourth one. Then, the insects were given the choice between two of the flowers they had not seen together before, such as the first and the third, or the second and the third.

During the experiments, the bumblebees’ preferences indicated that they could only retain very basic ranking memories for the flowers for an extended period of time. While they could remember that a flower had been better or worse during the training phase, they did not seem capable of remembering for more than a few minutes how sweet or rewarding the flowers were on their own, or even how much sweeter they were compared to other flowers.

While humans and other animals, such as starlings, are able to keep memories for both absolute information (e.g. how sweet something is) and comparisons (if something is sweeter than something else), bumblebees seem unable to memorize absolute information.

“Our results reveal an intriguing divergent mechanism for how bumblebees retain and use information about options, compared to humans and birds,” said study co-lead author Yonghe Zhou, a doctoral student in Biological and Behavioral Sciences at QMUL. 

 “It may be that the different strategies used by bumblebees and humans may have evolved because of their different diets,” added study senior author Fei Peng, a psychologist at Southern Medical University in China. “Maybe because bumblebees evolved to mostly only eat flower nectar, they never needed to remember the details and could survive and thrive simply using simple comparisons.”  

“Despite what may seem to be a poor memory strategy, bumblebees do very well in finding the most profitable flowers. It’s fascinating to consider how different animals, in their own ecological niche, can be similarly successful using such different strategies,” Yonghe concluded.

The study is published in the journal eLife. 

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By Andrei Ionescu, Earth.com Staff Writer