One of the first things I get asked when I tell people that I work on bee cognition (apart from ‘do you get stung a lot?’) is ‘bees have cognition?’. I usually assume that this question shouldn’t be taken literally otherwise it would mean that whoever was asking me this thought that there was a possibility that bees didn’t have cognition and I had just been making a terrible mistake for the past two years. Instead I guess this question actually means ‘please tell me more about the kind of cognitive abilities bees have, as I am very much surprised to hear that bees can do more than just mindlessly sting people’. So, here it is: a summary of some of the more remarkable things that bees can do with their little brains. In the first part of two articles on this topic, I introduce the history and basics of bee learning. In the second article, I go on to discuss the more advanced cognitive abilities of bees.
The study of bee cognition isn’t a new thing. Back in the early 1900s the Austrian scientist Karl von Frisch won the Nobel Prize for his work with honeybees (Apis mellifera). He is perhaps most famous for his research on their remarkable ability to communicate through the waggle dance but he also showed for the first time that honeybees have colour vision and learn the colours of the flowers they visit. Appreciating how he did this is perhaps the first step to understanding everything we know about bee cognition today.
Before delving into the cognitive abilities of bees it’s important to think about what kinds of abilities a bee might need, given the environment she lives in (all foraging worker bees are female). Bees are generalists, meaning that they don’t have to just visit one particular flower type for food (nectar and pollen), but can instead visit hundreds of different types. However, not all flowers are the same. They can vary in how good their nectar and pollen is, whether they have both of these food types or only one, and some flowers actually offer no food to bees at all (such as orchids that ‘trick’ bees into pollinating them). Bees make thousands of trips to flowers a day, as they aren’t just finding food for themselves but also for their colony. A foraging bee will visit a handful of flowers, drinking nectar and packing pollen on to her legs. She then returns to her colony, regurgitates the nectar (which becomes honey) and takes off her pollen loads. The honey and pollen is then fed to bee larvae (baby bees) by other worker bees. Therefore, if a bee wants to make sure that she’s getting the best food out there for her colony then she needs to rapidly learn which flowers have the best ‘rewards’ (nectar and pollen) available.
How does a bee learn this? Well, the simplest form of learning she uses is associative learning. Just as Pavlov’s dogs learned that a bell sound predicted food, thus making them salivate, so a bee learns that a particular flower offers, say, really good nectar. This can happen when she visits a single type of flower, for example if she lands on a lavender flower and finds some really good nectar, she will be then more likely to seek out another lavender flower in the future. Bees can also learn which flowers are the best in comparison to other flowers. For example a bee might land on one flower, collect some nectar and then leave and land on a flower of a different species and discover better nectar there. She would then not only learn to visit the second species of flower, but also learn to avoid the first species in preference to finding the second.
In the first experiment of its kind, von Frisch showed that bees can learn flowers based on their colour. To do this, he trained bees to collect ‘nectar’ (sugar water) off of coloured cards, for example the colour blue. He then placed the blue card amongst a number of other cards, all grey, but varying in how bright they were (from dark grey to light grey in colour). He then waited to see which card bees would try to land on. If bees can only see in black and white, then they would get confused and land on shades of grey that were similar in brightness to the colour blue they had learned to visit. However, bees didn’t do this: they visited the blue card and ignored all the grey ones, showing that they could perceive the hue (what we non-specialists often call the ‘colour’) of the card. Von Frisch then went on to show that bees also learn the scent of a flower when they visit it. Since then other scientists have shown that bees can also learn to re-visit flowers based on shape, size, pattern, temperature and even their electric field.
The work that von Frisch did formed the basis of research on bee learning today. What’s more, his techniques are still used to this day: pairing artificial flowers in the form of coloured or scented cards with a sugar water reward. In my next post I’m going to introduce some of the more amazing things we’ve discovered bees can do in the century since von Frisch.
von Frisch, K. 1956. Bees; their vision, chemical senses, and language. Ithaca, N.Y., Cornell University Press
von Frisch, K. 1967. The Dance Language and Orientation of Bees. Cambridge, Massachusetts: Harvard University Press.
Honeybee on flower: Cory Barnes
“Von Frisch color vision experimental setup” – isanhu