Napoleon is often quoted as having said that an army marches on its stomach. However, if the notorious French emperor was to reinvent this famous saying today, he might suggest that an army marches on its gut microbiome, the ecosystem of bacteria and yeasts that inhabits our guts. But we are not the only species that depends on our intestinal lodgers for health and digestion; the digestive tracts of honey bees are also packed full of bugs that contribute to their nutrition and immunity. So, an international team of scientists led by Yanping Chen from the Bee Research Laboratory, USA, wondered how the mighty insect's microbiome contributes to their resilience toward the pernicious deformed wing virus (DWV).
The team supplemented the diet (50% sugar solution) of some bees with pollen, while others received pollen and antibiotic supplements and an additional group just got a dose of antibiotics on top of their dinner. Then, the team tracked the bees’ health and nutrition and discovered that the bees that were fed antibiotics were in generally poorer shape than those that were fed pollen. The bees that were on antibiotics produced less mTOR protein, which is essential for regulating their energy use and metabolism, had lower expression of the genes encoding proteins that are essential for royal jelly production and were more vulnerable to DWV proliferating in their bodies. However, when the scientists supplemented the diets of the antibiotic-treated bees with pollen, they found that the bees recovered some of the royal jelly components, nutrient metabolism improved and they seemed to gain mass.
So the bees’ gut microbiome seems to be essential for their health and pollen in the diet may be a key player. ‘Our results illuminate the roles of bacteria in honey bee nutrition, metabolism and immunity’, say Chen and her colleagues.