I recently wrote about how bumblebees were able to perform some seemingly impressive feats, although the underlying reason they could do so was relatively simple. However, recent work by Caroline Strang and David Sherry has demonstrated that bumblebees are capable of another behavioural feat, never before shown in this species. In this post, researcher Caroline Strang tells us about this exciting new finding.
In order to do their job as pollinators, honeybees and bumblebees must engage in an extraordinary amount of learning. They have to learn how to get to and from their hive, which flowers provide the best nectar and how to extract nectar from those flowers.
It would be impressive enough for bees to learn all of this a single time in their lives, but they are in fact constantly having to learn new things. Honeybee hives are packed up and shipped from crop to crop, commercial bumblebees are shipped to greenhouses, and even wild pollinators must adapt to landscape changes.
Since we demand that bees adapt to changes in their environment it is important to determine whether or not they are capable of doing so. In fact, there is some reason to believe that bees cannot change their behaviour flexibly when the environment changes.
Bumblebees and honeybees tend to collect nectar from only one species of flower, a strategy called flower constancy. If the flower species from which a bee is collecting nectar disappears the bee must stop searching for that species and switch to a different species. In a recent article, Dr. David Sherry and I investigated whether or not bumblebees can cope with this problem in a laboratory.
We used a serial reversal task in which a bee is trained to land on a fake flower (a coloured square, either blue or yellow) for a sugar reward. Once the bee had learned to associate the colour with a reward, only visiting the colour of flower that was rewarded, we changed the task, so that landing on a different colour (either blue or yellow) was rewarded with sugar. The colour associated with sugar was changed back and forth repeatedly.
We found that each time the task changed the bees were able to adapt and learn to go to the newly rewarded colour. The bees even got better at adapting to the change the more times we changed the task.
These findings are particularly important because previous work on bees has shown that bees sometimes have difficulty changing their behaviour repeatedly and in fact lose the ability to tell the difference between rewarding and unrewarding colours or odours.
The studies showing bees to be inflexible required very rapid changes in behaviour and gave the bees little experience with each change before changing the task again. In our study the bees encountered even more changes than previous work, but were given more time and experience with each change before switching.
Our research on flexibility in bees shows that bees are capable of adapting to changes in their environment, but they need time to do so . Along with other work on learning in bees, this research contributes to our understanding of bees and may improve how we use them as pollinators.
The video below shows a bee taking part in the experiment
Caroline Strang, the author of this post, is a PhD student at The University of Western Ontario.
All photos and video taken by Caroline Strang
Strang, C.G. & Sherry, D.F. (2014). Serial Reversal Learning in Bumblebees (Bombus impatiens). Animal Cognition, 17, 723-734.