Propolis envelope promotes beneficial bacteria in the honey bee (Apis mellifera) mouthpart microbiome

Honey bees in the wild collect and apply plant resins to the interior of their nest cavity, which is called a propolis envelope. Propolis has been shown to have antimicrobial activity against honey bee pathogens, but the effect of propolis on the honey bee microbiome is unknown. Honey bees do not consume propolis but do manipulate propolis with their mouthparts. As honey bee mouthparts are used for collecting and storing nectar and pollen, grooming and trophallaxis between adults, feeding larvae, and cleaning the colony, they are an important interface between the bees external and internal environments and serve as a transmission route for core gut bacteria and pathogens alike.