by Kavitha Kannan
As spring rolls in across Europe, so do the bees. For some of us, the low hum of a bee hovering over lavender is one of the most reassuring sounds of the season. For others, it’s a cue to run, because the memory of a sting doesn’t fade easily.
But let’s look at it from the perspective of bees. Bees near trees or flowers are actually not so threatening. They’re simply minding their own business and foraging, finding food. They’re only bothered if you try to provoke them, as with any animal that tries to defend itself. It’s only when you get close to the hive, the colony’s home, its brood, its queen, that things change.
Provoke a honey bee colony, and you’re in trouble. Worker bees that take the role of ‘guards’ will detect the threat and release banana-smelling chemical compounds to other bees in the same hive to warn them about it. These signals, called ‘alarm pheromones’, recruit more bees to the site, pushing them to attack the predator. They bump into it, bite it, and sting it [1, 2]. However, stinging comes at a terrible cost. A honey bee’s barbed stinger lodges deep in mammalian skin, and when she tries to fly away, it tears from her abdomen and she dies.
This creates a paradox. The colony needs defenders, but it can’t afford to lose too many of them. If every bee stung every time, the colony would destroy itself in the act of defending itself. So how do honey bees regulate this?
This was the question at the heart of my PhD, which I began in 2020 at the University of Konstanz, on the shores of Lake Constance in southern Germany. My supervisor, Morgane Nouvian, had been chipping away at this paradox from different angles. Her lab had already uncovered two braking mechanisms. First, the alarm pheromone, which we tend to think of as a straightforward “attack!” signal, actually follows a more nuanced dose-response curve. At low concentrations, it recruits stinging. But at very high concentrations, bees collectively dial back their responsiveness, hitting a plateau where some sting and others don’t [3]. So the alarm signal isn’t just a positive feedback signal. It has a built-in brake. Second, it was also identified that as group size increases, the likelihood of any individual bee stinging decreases [4]. The more bees around, the less likely each one is to commit.
But I wanted to push this further. If every bee doesn’t sting, then which bees sting? Is it random each time, or do some individual bees choose to always sting versus others that choose to always not sting?
To test this, I couldn’t exactly stand in front of a hive and take notes. That wouldn’t be safe science. Instead, I used a stinging assay that my PhD supervisor had designed: a controlled setup that mimics a predator attack at the hive entrance, complete with a rotating “dummy predator” and channels that release a synthetic alarm pheromone. I tested individual bees repeatedly, four times each, across different conditions: alone or in pairs, with or without the alarm pheromone.
What I found was the biggest result of my PhD. Individual honey bees are consistent in their stinging responsiveness. Some bees chose to sting again and again, across every test. Others simply refused, no matter the provocation. This wasn’t noise. It pointed to something more interesting: bees have an individuality when it comes to stinging [5].
With the social factors layered in, the alarm pheromone and the presence of a companion bee, the stinging responsiveness varied slightly. The pheromone pushed bees toward stinging, while the presence of another bee pulled them away from it. But the bees’ individual personalities persisted through it all. A gentle bee mostly stayed gentle. An aggressive bee mostly stayed aggressive. It was as though the decision was already made internally, probably driven by neurophysiological factors, but the social context could pull it to either side to some extent.
But a pair of bees is still a long way from a real colony. So, I asked a follow-up question: what happens in larger, more realistic groups? I colour-marked individual bees and tested them first within groups of six, to characterise each bee’s behaviour, coding stinging bees as “aggressive” and non-stinging bees as “gentle”. Then I shuffled them into new groups, either an all-aggressive, all-gentle, or mixed, and tested them again. Individuals stuck to their decision even when surrounded entirely by bees of a different temperament. Group composition didn’t reshape their behaviour.
Our finding was a first for the species: honey bees have individual stinging tendencies. This is analogous to a “personality”: a consistent preference for one behaviour over another, regardless of social context. Think of someone who’s talkative in any group, whether the others are chatty or quiet.
What drives these consistent preferences is still an open question. It’s likely a combination of genetics, age, and experience. An earlier study found that colony genetics dominates over individual genetics in shaping aggression in bees [6], but our results suggest that the story is more complicated – individual differences persist within a single colony and require further investigation. Moreover, my study only focused on the defensive bees from the hive entrance without knowing their age or tasks. Tracking individual bees at these finer details is likely to give us more information on the question of which bees are attacking and why.
So the next time you see a bee or a bee hive, maybe it’s worthwhile to think about how it’s composed of individuals with their own personalities, their own machinery for taking in different information and making a decision. Perhaps to even sting you!
- Nouvian, M., J. Reinhard, and M. Giurfa, The defensive response of the honeybee Apis mellifera. The Journal of Experimental Biology, 2016. 219(22): p. 3505-3517.
- Kannan, K., C.G. Galizia, and M. Nouvian, Olfactory Strategies in the Defensive Behaviour of Insects.Insects, 2022. 13(5): p. 470.
- López-Incera, A., et al., Honeybee communication during collective defence is shaped by predation.BMC Biology, 2021. 19(1).
- Petrov, T., et al., Extracting individual characteristics from population data reveals a negative social effect during honeybee defence. PLOS Computational Biology, 2022. 18(9): p. e1010305.
- Kannan, K., C.G. Galizia, and M. Nouvian, Consistency and individuality of honeybee stinging behaviour across time and social contexts. Royal Society Open Science, 2025. 12(1).
- Avalos, A., et al., Genomic regions influencing aggressive behavior in honey bees are defined by colony allele frequencies. Proceedings of the National Academy of Sciences, 2020. 117(29): p. 17135-17141.
Author
Kavitha Kannan recently completed her PhD in Biology at the University of Konstanz, Germany. She finds the cross-over of animal behaviour and neurobiology (neuroethology) fascinating, and is also drawn to conservation science. She is currently exploring her next steps in research and science communication.
Illustrator
Vithur Varenya is an aspiring developmental biologist currently working as a Junior Research Fellow at SRMIST. Her passion for art began with observational sketching, and she especially enjoys illustrating elements of nature, often decorating her notes with creative doodles. Outside the laboratory, she spends her time exploring new subjects, experimenting with new art styles, and reading books.
This article was written as part of Club SciWri’s Science Writing Workshop, an initiative aimed at nurturing new voices in science communication and helping participants explore how to make complex ideas accessible to wider audiences.
Workshop conducted by Saurja Dasgupta, Ananya Sen, Rohini Subrahmanyam, Sumbul Jawed Khan and Roopsha Sengupta
