Bees make more friends when they’re full of healthy gut bacteria

The astonishing uniformity of this microbial ecosystem around the planet—similar in all species, including sociable bumblebees—indicates that the bacteria are essential to honeybee survival in some way. Since bees with healthy microbial partners develop into adults with more complicated social ties and even different brain chemistry than bees with sterile guts, research earlier this week in the journal Nature Ecology and Evolution may help to partially explain why.

In many animals, the community of bacteria, fungi, and other microbes known as the gut biome has a potentially significant but mysterious function. Human cognition may even be shaped by it. According to Joanito Liberti, the paper's principal author and an evolutionary biologist at the University of Lausanne in Switzerland, "the gut-brain axis is particularly interesting from an evolutionary standpoint, because gut symbionts were probably there when the first neuronal systems formed." There are some indications that the microbes may influence our behavior; however, since we have many more organisms inside of us than honeybees do, it is difficult to link one to the other.

And the significance of gut flora in this investigation was clear. This [result] really demonstrates that the gut microbiota may be essential to the hive's operation, according to Liberti. The crucial function of those gut bacteria may also contribute to an understanding of why bees are so susceptible to hazards from humans, notably agricultural toxins.

Because they are born sterile, unlike human infants, honeybees are especially well-suited to microbial experiments. Bees don't acquire their microbial cargo until they reach adulthood and start interacting with other hive members. The scientists are able to grow blank-slate bees without the use of any antibiotics by removing days-old grubs from the hive and incubating them in sterile conditions. Half were treated with bacteria from the lab's microbial bank again. The other children were born and raised as virgins.

Those infertile bees didn't exhibit any overt indications of suffering, such as poor flying or collapsing dead, at least not during the 10-day study period. Just like their microbially-complete siblings, they didn't socialize as much. They were significantly less likely to "touch heads" with other bees, which in bee lingo implies to exchange food or knowledge. They also interacted with the other members of the group "more spontaneously and equitably," according to Liberti. These bees appear to have formed "friendships" as a result of their stomach microbiota.

Egalitarian bees may seem like a wonderful thing, but Liberti claims that a colony with several specialized connections is really better at managing the intricacies of the world. He claims that "not everyone is doing everything at the same time." When taking care of a brood, it is more important to have information on the brood than whether foragers discovered a food patch.

The team discovered disparities within the bees that were based on the way their DNA was functioning. In the sterile population, a third of the 60 distinct compounds that were examined in bee brains were less prevalent. In the neurotransmission or brain fuel supplies, four specific amino acids that were much more prevalent in bacterial-bees were specifically involved. Memory, vision, smell, and taste-related genes were all impacted in the brain tissue itself; in other words, the microbiota interfered with the replicating machinery that converted those genes into chemicals.                                                                                    

According to Liberti, "maybe the microbiome doesn't directly affect the survival of bees." However, if their brains are not functioning properly, they will naturally be less effective at storing the food they gather and making the honey they require. This will eventually have an impact on the survival of the entire hive.

That might contribute to explaining why wild and domestic bee populations are in such a state of stress. High doses of a typical herbicide have been shown to disrupt the microbiomes of honeybees in studies over the past ten years. Without actually killing the bees, the weedkiller may have an impact on their sensory and learning abilities.                                                                                                    

According to Liberti, certain agricultural exposures may change insects indirectly through the microbiome, but depending on the dose, they may also have direct effects. In studies he co-authored earlier this year, it was shown that persistent, low-level pesticide and herbicide exposure—possibly more representative of real-world doses—damaged honeybee metabolisms without altering their microbiomes. Numerous typical pesticides, herbicides, fungicides, and even antibiotics have already been demonstrated by scientists to directly damage honeybees.

It's possible that we've been unknowingly affecting the microbiome, another crucial aspect of honeybee functioning.