5 Bee Research Papers Everyone Should Read

It has only been a few years back since I had come across a scientific study in which a bumblebee had been taught to roll a ball across a table. It made me laugh at the time. Because besides it was really fun and cute, it was also such an odd task for a bee to perform.

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A small insect, with a brain smaller than a grain of rice, was solving a problem it had never faced in nature. It made me stop and think about how often we underestimate the animals around us simply because they experience the world differently from us.

That is what I want to share with you today. Five research papers that changed how scientists, and slowly the rest of us, understand bees. Not just the headlines. Not just the “bees are declining” stories we see repeated everywhere.

The actual research behind them. The studies that made us look at bees differently.

I am not going to pretend these papers are easy reading in their original form. Scientific papers are written for other scientists and sometimes they are full of technical language to make your eyes cross.

My job here is to take what is underneath that language and explain why it matters. Because science is not only about collecting facts. It changes the way we see the living world. So, make yourself a cup of tea…

…And let us start with the bumblebee that played a game.

Full title: Bumblebees show cognitive flexibility by improving on an observed complex behavior Researchers: Loukola, O. J., Solvi, C., Coscos, L., & Chittka, L. (2017) Science, 355(6327), 833–836.
https://pubmed.ncbi.nlm.nih.gov/28232576/

This is what happened. Scientists from Queen Mary University of London exposed bumblebees to a tiny platform with a yellow ball attached to it. The bees received a sweet treat for pushing the ball to its center point. Simple enough. Except pushing a ball is not something bees normally need to do in their natural lives.

Untrained bees observed their peers who had been trained perform the task prior to attempting it themselves. The trained “demonstrator” always pushed the ball that happened to be furthest from the centre, because that was simply how it had learned the trick. And this is the point which made me pause while reading this article. When the untrained bees tried the task alone, most of them did not copy the exact route they had watched. They worked out that any ball would do, and pushed the closest one instead, because that was the smarter option. Later, when researchers swapped in a ball of a completely different colour, the bees solved the task anyway. They had understood the point of the game, not just memorised a sequence of moves.

A bumblebee brain holds fewer than one million neurons. A human brain holds somewhere around eighty six billion. For a long time, that gap was used as a lazy shortcut, small brain, small mind, nothing much going on in there. This study and the pile of research that followed it, made that shortcut impossible to defend. Something was clearly going on in there.

If a study like this makes you want more of the same, this is exactly what I write about in Bees & Beyond. Subscribe for weekly articles.

Full title: Wild Pollinators Enhance Fruit Set of Crops Regardless of Honey Bee Abundance Researchers: Lucas A. Garibaldi, Ingolf Steffan-Dewenter, Rachael Winfree and a very large international team Published: Science, March 2013
https://www.science.org/doi/10.1126/science.1230200

For a long time, the public conversation around pollination was, put simply, all honey bees, all the time. Managed hives, trucked from farm to farm, doing the pollinating work while everyone assumed wild, unmanaged bees were nice but optional, like a spare set of hands nobody really needed.

This was the research paper that tested that hypothesis for real, for the first time at a scale nobody had attempted before. The scientists pulled together data from 41 different agricultural experiments across 5 continents, everything from coffee to almond to watermelon and looked at what actually determined whether flowers turned into fruit.

The answer surprised a lot of people who should have known better. Visits from wild insects increased fruit set consistently, almost everywhere, regardless of how many honey bees were also present in the same field. And critically, wild bees and managed bees worked in parallel, each adding something the other did not fully replace.

If you keep bees the way I do, close to nature and paying attention to more than just the honey box, this paper is your evidence. Wild, solitary bees, bumblebees, all the unnamed and unglamorous pollinators working in hedgerows, doing unreplaceable work.

Full title: Neonicotinoid pesticide reduces bumblebee colony growth and queen production Researchers: Penelope R. Whitehorn, Stephanie O’Connor, Felix L. Wäckers and Dave Goulson Published: Science, April 2012
https://www.science.org/doi/10.1126/science.1215025

I want to walk you through this one slowly, because the design is so simple it almost feels unfair how much it revealed.

Researchers at the University of Stirling took colonies of a common bumblebee, Bombus terrestris, and split them into two groups. One group was exposed to imidacloprid, a widely used neonicotinoid pesticide, at levels a bee would realistically encounter on a treated crop, delivered through nectar and pollen, nothing exaggerated. The other group received nothing. Both groups were then placed outdoors, where the colonies could develop and forage under natural conditions.

The treated colonies grew more slowly. That much you might expect. But the real result came later, at the point in a bumblebee colony’s life when they produce new queens. They are the only individuals who overwinter (to found next year’s colonies). The treated colonies produced 85% fewer queens than the untreated ones.

Sit with that number for a second.

85%.

A near total collapse in the one output that actually determines whether a wild bumblebee population continues to exist. And here is the part that unsettles me most as a beekeeper. A colony affected like this can look completely fine from the outside. Workers still flying, still foraging, still doing their visible job. The damage is happening somewhere you cannot see it, in the next generation that never arrives.

This paper, alongside further research that built on it, became part of the evidence base that led the European Union to restrict neonicotinoid use on flowering crops.

This is precisely the kind of story I want you reading with your morning coffee. Subscribe to Bees & Beyond for weekly articles.

Full title: More than 75 percent decline over 27 years in total flying insect biomass in protected areas Researchers: Caspar A. Hallmann, Martin Sorg, Eelke Jongejans, Henk Siepel and colleagues Published: PLOS ONE, October 2017
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0185809

This study is usually referred to as the Krefeld study after the German entomological society whose members had been conducting insect trap studies in more than thirty different protected areas since the 1980s. These were mostly volunteer entomologists, who collected samples in the same manner, year after year, decade after decade. Nobody was paying much attention to them at the time.

When Hallmann and his colleagues finally sat down with this long, patient dataset and analysed it properly, the result stopped a lot of people, myself included, in their tracks.

Across sixty three protected areas in Germany, the total weight of flying insects had fallen by 76% over twenty seven years, and by as much as 82% during peak summer months. This was not one species declining while others picked up the slack. The overall biomass of flying insects had fallen dramatically. The decline was observed across the different protected areas included in the study. The researchers examined possible explanations, including weather and habitat changes, but the scale of the decline remained deeply concerning.

I want to be clear about why a study of “flying insects” belongs in an article about bees specifically. Bees do not live in a bubble. Bees are part of a much larger insect world. When flying insect numbers decline, the effects do not stop with pollination. Many other animals depend on insects as part of the wider food web. When someone measures the total weight of insects in the air and finds three quarters of it missing, they are measuring the health of the entire structure bees depend on. The flowers, the undisturbed soil, the food web around them, all of it.

Before this paper, insect decline was a worry mostly shared among entomologists at conferences nobody outside the field attended. This is the study that dragged it into the open and made governments start asking questions.

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Full title: Climate change impacts on bumblebees converge across continents Researchers: Jeremy T. Kerr, Alana Pindar, Paul Galpern, Laurence Packer and colleagues Published: Science, July 2015
https://www.science.org/doi/10.1126/science.aaa7031

Most animals facing a warming world do a version of the same thing. They shift their range towards the poles, or up into the hills, chasing the cooler conditions they are built for. It is not a perfect solution, but it is a strategy and many species manage it reasonably well.

Kerr and his team wanted to know if bumblebees, many of which are adapted to cooler conditions, were pulling off the same trick. They gathered more than a century of bumblebee records from Europe and North America, including historical observations, museum specimens and survey data, then compared how species ranges had changed over time.

The pattern was consistent on both continents, which matters more than it might sound, because two separate landmasses telling the same story is much harder to dismiss as coincidence. Bumblebees were losing ground at the warmer, southern edges of their ranges, but they were not expanding northward quickly enough to compensate for those losses. Some species climbed higher into the hills instead, trying to find cool air by going up rather than sideways. And crucially, the researchers ruled out land use changes and pesticides as the explanation. This was temperature, plain and simple.

It seems some bumblebee species may be limited by the cooler conditions they evolved for. As temperatures rise, the warmer southern ranges become increasingly unsuitable, while they are not always able to expand into cooler areas quickly enough to replace those losses.

Five papers is nowhere near enough to cover everything scientists have discovered about bees. There are hundreds more I could have chosen and that is probably why I will never run out of things to write about.

I did not choose these papers to frighten you and I hope none of them landed that way. I chose them because, together, they show something I find genuinely moving. Bees are not background scenery. They are the subject of careful, patient, sometimes decades-long human effort to understand them properly and every one of these papers, even the difficult ones, is a form of paying attention.

Bees pushing balls they never needed to push. A solitary bee doing half the pollination work nobody gave her credit for. A queen that never gets born because of a chemical. An insect population thinning out in traps for thirty years. Bumblebees stuck between a warming south and a north they cannot quite reach.

These separate studies are telling us one long story about tiny creatures that are far more capable, far more essential and far more fragile than most of us were ever taught.

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Thank you for reading and I will see you in the next one.