Diet-Induced Alterations in Gut Microbiota and Antimicrobial Peptides Profiles of Honey Bees (Apis mellifera)

Honey bees ( Apis mellifera) are essential not only for honey production but also as key pollinators in agriculture. Worker bees perform age-related tasks, remaining inside the hive for approximately the first 20 days after emergence and foraging outside thereafter, which is critical for colony maintenance. However, complex stressors weaken the bee’s immune system and disrupt its gut microbiome. Given that the gut microbiome plays an essential role in immune defense, this disruption renders honey bees susceptible to pathogens, contributing to colony collapse disorder. In this study, we investigated the effects of larval and adult diet on gut microbial communities and antimicrobial peptides (AMPs) expression in worker bees over 20 days. Each group was initially assigned to one of two dietary treatments: a 50% sucrose solution or honey. The adult individuals that developed under these conditions were subsequently maintained on their respective initial diets, thereby generating four experimental groups. At the end of the feeding period, gut microbiota composition and the expression of AMPs were quantified using real-time quantitative PCR. Additionally, cultivable gut bacteria were isolated and identified for comparative analysis. Our results show that feeding honey reduced harmful bacteria and increased beneficial bacteria associated with AMPs expression. These results suggest that diet during development can improve gut health and immunity in honeybees.