Effects of propolis and other plant natural products on honey bee health, detoxification and gut microbiota

There is a growing demand among beekeepers for more sustainable treatments to promote honey bee health. Certain plant natural products (PNPs), such as honey bee-collected resins (propolis) and beekeeper-applied essential oils, positively impact bee health, but the specific mechanisms underlying their effects need more research. This project aims to understand how propolis extracts and essential oils added to the honey bee diet modulate different aspects of bee health. Cages of newly emerged bees were provided pollen paste and sucrose syrup containing either i) Brazilian or ii) Louisiana propolis extract, or iii) lemongrass, iv) spearmint, or v) thyme oil at different concentrations for seven days. Control treatments consisted of either kanamycin (negative control), emulsifiers, or just sucrose. The sucrose, Brazilian propolis, and lemongrass-fed cages had the longest median lifespans while the thyme and spearmint-fed cages had the shortest. Analyses of whole bee abdomens revealed some differences in the abundances of prominent bacterial gut taxa in bees fed kanamycin, spearmint, and thyme relative to the controls, but overall the bee gut microbiota appears robust to perturbation by even high concentrations of PNPs. Effects of the PNPs on other metrics of health and detoxification pathways will also be discussed.