Phoning the Queen with Fanning and Pheromones

The reappearance of honey bees is a sign that spring is finally here. The worker bees leave the hive and collect pollen and nectar from the surrounding flowers. Not only are bees important pollinators of our crops and gardens, their group behavior has also fascinated behavioral scientists. One of the most known behaviors bees do is called the “waggle dance.” This is when bees communicate where to go by moving their butts in different patterns, a form of nonverbal communication that astound us humans. These types of non-verbal communication are common across the animal kingdom.

Another form of non-verbal communication that bees use is the production of pheromones. Every animal has pheromones, chemical signals produced by the body and usually used to communicate. In a new study, Dieu My T. Nguyen and colleagues sought to understand how bee movement and pheromones interact to help individual bees locate the queen. Prior research showed that honey bee swarms are a collective behavior and occur because individual bees are tracking the queen’s pheromones. The researchers wanted to understand how far these pheromones can travel in space and time and if the behavior of the bees increased the distance the pheromones traveled and the time they were detectable. 

Technology Teaches Us About Nature

The team used video recording and machine learning analyses to understand how the bees change their behavior to increase pheromone detection. When a bee is “scenting” pheromones, it raises its abdomen while fanning their wings vigorously to push the pheromone scent to the surrounding bees. The researchers looked for evidence of this behavior in the video recordings.

For the videos, bees were placed in a 2D arena. Imagine a busy street intersection with a camera viewing the movement of all the cars and people from above. The first thing the researchers did was separate the workers from the queen so they could measure how long it took the workers to reach the queen. The queen was placed on one side of the arena and the workers on the other. Using machine learning and knowledge about the diffusion of chemicals into the air, the researchers built a model to estimate the direction of the scents for each worker bee. When bees are farther from the queen they are in the “scenting” position with raised abdomens then as more and more bees aggregate around the queen the number of bees with the scenting position decline. The researchers then used the results of these experiments to develop models to predict how swarms might form with different distances and densities. 

Collaboration is Key

Interestingly, during the arena trials, not every bee was in the scenting position. In fact, the researchers observed collaborative behavior between the workers. Some worker bees were in the scenting position, seeking out the pheromones of the queen. These bees frantically fanned their wings, pushing the scent of the pheromone behind them towards the other bees who then began to congregate around the queen. Like the game of telephone where one person whispers a phrase to the person next to them and around the circle, bees are doing the same thing, although they are more successful! 

In a game of telephone, the final phrase is often drastically different from the initial phrase. The game shows that with verbal communication, many details can get lost in translation. With the bees, however, their game of telephone is passing pheromones from a scenting bee to a non scenting bee and so on. It’s a collaboration that benefits all in the group and helps them locate the queen.

This experiment was not only instrumental in showing how we can use technology to understand communication in the animal world, but also highlights communication patterns that at first, seem foreign to humans, a species that values verbal communication. Scientists are divided on the role of human pheromones for communication, however, we use non-verbal communication such as eye-rolls, smirks, and a firm handshake to communicate with others in our species. Perhaps we can even learn from the bees and when collaborating with a group, we should make sure we have key members in the group, facilitating the success of others and thus, a more productive game of telephone.

Source: Nguyen, D.M.T, Iuzzolino, M., Mankel, A, Bozek, K., Stephens, G.J., and Peleg, O. 2021. Flow-mediated olfactory communication in honybee swarms. Proceedings of the National Academy of Sciences, 2021; 118 (13): e2011916118 DOI: 10.1073/pnas.2011916118