Gut microbes are important for digestion and immunity in humans — and may also be beneficial to bees.

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Waldan Kwong at Yale University in New Haven, Connecticut, and his colleagues hand-reared larvae of the honeybee (Apis mellifera; pictured) in the laboratory. They allowed some bees to develop without gut bacteria, and inoculated others with bacteria found in nest-mates' stomachs. Compared with bees that lacked gut microbes, insects with bacteria made 28 times more apidaecin — an antimicrobial protein that protects against invading pathogens but doesn't seem to affect the gut bacteria. They also had higher survival rates when infected with the bacterium Escherichia coli.

The authors say that gut microbes, as well as other variables such as genetics, could affect the immunity of commercial bees, which are threatened by multiple pathogens.

R. Soc. Open Sci. 4, 170003 (2017)