Even though they have a tiny brain, honeybees are amazingly good at finding their way in a complex environment. What do we know about it and why should we care (even if we don’t like honey)?
When I started working with honeybees, many years ago, I didn’t know much about them – I only knew they can sting and make honey. I couldn’t even tell a bee from a wasp. I would always hear my supervisor say bees were very fascinating creatures and think to myself ‘well, I am not fascinated’. For months, I was working with them and quite unhappy with their pretentious choice to come out of the hive only when there is sun. So, on sunny days, I was stuck in the lab running experiments, and on rainy days I had nothing to do. How annoying.
Until one day, I went out of the lab for a free field research project to study bees in their natural environment. That was when the magic happened: I fell in love with them!
Before that, I was always afraid I would get stung. After that, I spent weeks sitting in front of a hive day after day, catching and releasing bees, with bare feet, arms and face. Do you know how often I got stung? Only once: when I accidentally squeezed a bee which had landed on my arm. Yes, bees were landing on us all the time – on their way home from “work”, just before they entered the hive, they would sit on my arm and flap their wings so fast that I could feel the wind, like a tiny fan. They would fly past so close that I could feel how fluffy they are. Yes, bees are fluffy! They are also extremely disciplined: one of our experiments included sitting in the field with a sugar solution and writing down the numbers of the bees which would visit the feeding place. We would usually open the feeder at 9 a.m. The bees were so punctual that on days when we were a few minutes late on that exact spot in the field there would be already several bees, impatiently flying in circles and searching for their sugary water! On top of that, each one of them would have its own special schedule of visiting me. Some bees would come between 9 and 12 a.m. in regular intervals and then stop coming, while others would eventually fly by around 11 a.m. to check the situation and linger around for a while. After a few days I knew all my “visitors” so well that I would start worrying that something happened to #11, if it failed to be on time. Another thing which never ceased to amaze me was that bees always knew what the weather was like without even leaving the hive. They didn’t even bother to send someone out to check whether it is worth going foraging or not – on bad days they just stayed in.
Now, I know it sounds like we were just playing around with the bees, but in fact we were working really hard. Open field experiments mean no weekends, since every day is precious for collecting data. It also often means getting soaked in the rain or being under the blazing sun for hours on end. It requires a great deal of patience and ability to focus because sometimes you spend hours watching bees come and go, but drifting away in your thoughts is not an option – you shouldn’t miss a single visit. At the same time, it means working in isolation, because your nearest colleague is maybe one kilometer away and you only have a walkie-talkie connection. For weeks on end, I forgot how it felt to wear nice (and clean!) clothes or shoes other than rubber boots, or to eat anything else than sandwiches. I forgot the whole world beyond the tiny village lost in the fields we called home for a while: a place so rural and quiet that no one ever bothered to lock their house or car. The most entertaining event of the week was when we drove to the nearest supermarket for groceries. I remember being overwhelmed by all the colors, all the lights, the sheer infinite number of different products in their shiny packages and by the presence of people I never saw before! I felt like I had never been to a more magical place before.
Nevertheless, despite all these challenges, working on this project was extremely exciting. We wanted to find out how bees find their way around, or in other words: how bees navigate. Foragers can fly very long distances from the hive to a site rich in nectar or pollen but always seem to find their way back without any effort – how do they do that?
Scientists who study navigation believe there are different principles to finding your way.
The simpler one is through a path made of straight lines (vectors). You go from A to B – that’s one vector. Then you turn left and continue to C and that is another vector. With vector integration you can now easily find your way back to A without returning first to B. Another, more complex, way is to have a map in your brain: a cognitive map.
Humans are thought to navigate through such a cognitive map. In a part of our brain, called the hippocampus, there are nerve cells which become activated when we go to a certain place and, as we move, other cells become activated to match our new position. This process has been studied in rats in great detail, and it is thought to be pervasive in most mammals. Thus, mammals not only use a cognitive map, but we even know exactly where it sits: in the hippocampus. But bees have no hippocampus, because their brain is structurally very different from that of a rat. They also have only about one million nerve cells in the brain – a rat has 200 times more! So it was pretty logical to assume that bees use more simple methods to navigate. However, there is more and more evidence that bees may also use a cognitive map. As you can imagine, this is quite a challenging idea and not everyone likes it. However, in science, any new idea is first met with skepticism and doubt. Although this sometimes makes scientific progress quite hard and slow to happen, ultimately this is a good thing, because if a scientist has a new hypothesis, she/he has to be able to prove it with experiments to convince other scientists too.
So the tiny bee brain has an even tinier map of the field, the flowers, the river, the small forest, the hive.
But who draws this map? When a bee hatches, it has no idea what the world outside looks like. It’s all nice and cozy in the hive and the baby bee stays inside until it is strong enough to fly. One beautiful day it flies out, all alone. Hello world! This must be quite an awesome moment, and scary too. But the bee is fearless, it flies out and looks around. The first flights are called orientation flights: their purpose is to explore and study the area around the hive. Sometimes the bee just makes a short flight and stays close to the hive, but it can also go far away, even more than 100 meters during its very first flight! Each orientation flight is done in a new direction, so that the bee gets to know the surroundings of the hive in a perimeter of 500 meters and draws a tiny cognitive map. The bee often turns around to have a look at the hive and remember it well so that it can recognize it easily on its way back. Once it feels confident that it knows the area well, it can go on a foraging flight, which is usually much longer than an orientation flight.
How do we know all that? Of course we can learn a lot just sitting by the hive and watching the bees, but we will not know exactly where the bee went and whether it was the first flight or the fifth. So we needed a more elaborate strategy: after hatching, bees were labeled with numbers. Baby bees are super cute: they look exactly like adults but their sting is still soft and cannot yet penetrate our skin. Once labeled, we put them back in the hive. When a bee then came out of the hive a few days later, we could read the label and know that this bee was leaving the hive for the first time. Before it took off, we glued a mini antenna to its back, a so-called radar transponder. The flight track was then recorded by a radar, just like those used to track planes at the airport. Well, a less powerful one, obviously, but the idea is the same: you sit in front of a screen and see bright dots on black background: each of this dots represents a bee. The work at the radar was a bliss when the weather was wet or windy, but staring at blinking dots on a black screen for hours could really induce hallucinations. These dots were burned into my retina and continued blinking long after I had switched off the radar and left the field for the night. Nonetheless, the dots combined made a track and many tracks together gave us knowledge about the way a bee learns to navigate. We still have more questions than answers about bees’ behavior, about navigation and about the cognitive map, but the more we know, the more exciting it gets.
After that summer, I changed my field of work completely and never worked with bees again, but the deep sympathy for these super-smart and fluffy creatures never really left me.
Distant family members still ask how the bees are doing whenever they meet me, oblivious to the fact that I stopped having anything to do with bees years ago. Working in the lab, sometimes I recall the warm smell of the grass field at dawn, the magnificent sky above my head and the sense of freedom despite the busy schedule. In these moments I think, one day I want to have a bee hive in my garden.
Oh and by the way: next time you are sitting outside on a sunny day and a little insect is flying around, landing on your piece of cake and driving you nuts, look carefully: it has yellow-black rings, a sand clock shape, and it’s a wasp. Bees, as I told you before, are fluffy and grey. Also, bees are nice, and they wouldn’t come to bother you, because they have more important stuff to do.
1. ORIGINAL ARTICLE ABOUT NAVIGATION IN HONEYBEES: DEGEN J ET AL. (2015) EXPLORATORY BEHAVIOUR OF HONEYBEES DURING ORIENTATION FLIGHTS. ANIMAL BEHAVIOUR 102:45–57.
2. REVIEW ARTICLE ABOUT NAVIGATION IN HONEYBEES: MENZEL R & GREGGERS U (2015) THE MEMORY STRUCTURE OF NAVIGATION IN HONEYBEES. J COMP PHYSIOL A NEUROETHOL SENS NEURAL BEHAV PHYSIOL 201(6):547–561.
3. NOBEL PRIZE FOR THE DISCOVERY OF PLACE CELLS: HTTP://WWW.NATURE.COM/NEWS/NOBEL-PRIZE-FOR-DECODING-BRAIN-S-SENSE-OF-PLACE-1.16093
4. NICE BBC ARTICLE ON BEE TRACKING: HTTP://WWW.BBC.COM/NEWS/MAGAZINE-23448846
Petya Georgieva (@PBGeorgieva.) is a postdoctoral fellow at the Flemish Institute of Biotechnology (VIB) in Leuven, Belgium. She works on immune cells in cancer while training for her first marathon and learning Dutch.
Edited by: Ivo Marcelo (section editor), Clara Howcroft Ferreira (editor-in-chief)