Breaking down the microbiology world one bite at a time
Social dynamics within a beehive are rooted in the gut
Beehives are notorious for their dynamic social networks, with the Queen Bee sitting at the top of this elite hierarchy. Worker bees, drones, and non-reproductive female bees, all have a unique role to play in the upkeep of the hive. Social networks are found in other animal species as well, such as dolphins, elephants, and ants colonies. However, many generations of researchers have pondered over the question, “How and why do these animals create the vast arrays of social dynamics that we observe?”
Behavior often begins in the brain. Recent studies have uncovered a deep connection between the bacteria that live on (and inside) animals, and how they regulate the animal’s health. It is even known that one’s microbiome can change their brain chemistry. Since a honeybee hive is smaller and more manageable than a elephant herd, researchers at University of Lausanne, in Switzerland, studied the social dynamics of these creatures in relation to the bacteria residing in their guts, and published their work in Nature Ecology & Evolution earlier this year.
To test the effects of the gut bacteria on social behavior, the scientists took two different beehives, one where they removed all of the gut microbes and the other where the bees had the bee-typical gut bacteria. Through the use of an automatic tracking system which captured the bees’ flight patterns and interactions, the authors monitored the social behavior of hundreds of worker bees for seven days. They found that bees missing their gut bacteria became less specialized in their jobs, and had less social interaction compared to the bees that maintained their gut microbiome. Through this simple set up, the scientists were able to elegantly show the microbiome is playing some role in social dynamics amongst the bees, but how can these tiny, microscopic creatures have such an impact?
The authors looked at the brains of the bees to find their answers. Small chemicals such as serine, glutamine, aspartate and glycine, were severely reduced in the brains of bees missing their gut bacteria.
These chemicals are well known factors that help in proper brain function. The first reports of serine in the brain came from a scientist named Hashimoto in 1995, but it wasn’t until nearly 10 years later, in 2004, that their role was uncovered. Scientists in London described these chemicals as helping maintain the timing of brain signaling and also recycle some of the neurotransmitters to reduce brain energy loss. Thus the world of metabolites affecting brain function exploded, with the guts of our bees adding to the growing connection between the gut and the brain.
Digging deeper, the authors wanted to investigate why these chemicals differed amongst the two types of bees. They speculated that “the gut microbiota specifically increases the abundance of brain metabolites, which could be due to bacterial signals received from the gut or the direct transfer of microbial or dietary-derived metabolites from the gut to the brain.”
Next, they examined the brains themselves, attempting to discover the effects these metabolites were having on brain function. Since the authors were focusing on social behavior, they explored three regions of the brain involved in memory and learning. To the scientists’ surprise, the brains remained largely constant between the groups of bees. The brain region that received the most change was the region involved in smell and taste.
The authors also found a likely culprit- the bacterium that elicited the most drastic changes amongst the bees was none other than Bifidobacter asteroides. This large bacterial genus is typically found nestled in the guts of animals, from humans to insects, is typically harmless, and can help in digestion and other physiology. One paper even describes them as “among the first microbes to colonize the human gastrointestinal tract and are believed to exert positive health benefits on their host”. These bacteria are also frequently added to foods as an active ingredient to help with digestion!
B. asteroides is the one of the most common gut bacteria in insects, making its debut as a regulator for brain function and social skills. The next time you eat a Chobani yogurt seeking to gain some extra protein and give your gut some love, think of the bees and Bifidobacter, making your brain happier and you — a buzzing socialite.
Link to the original post: Liberti, J., Kay, T., Quinn, A. et al. The gut microbiota affects the social network of honeybees. Nat Ecol Evol 6, 1471–1479 (2022). https://doi.org/10.1038/s41559-022-01840-w
Featured image: Honeybees scurrying over a honeycomb. Credit: https://www.rawpixel.com/image/6036230
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