Abstract

Simple SummaryTo determine the biologic function of gut bacteria with no host specificity in honeybee larvae, honeybee larvae were treated with antibiotics for disrupting the gut bacteria. Then, the body weight, development time, and expression of nutrient metabolism genes and immune genes of honeybee larvae were investigated. The results demonstrated that the disruption of gut microbiota by antibiotics weakened the nutrient metabolism, decreased the body weight, extended the development process, and decrease the immune competence of honeybee larvae, indicating the vital roles of gut bacteria in bee larvae fitness.AbstractSymbiotic bacteria could increase the nutrient provision, regulate the physiological state, and promote immunity in their insect host. Honeybee larvae harbor plenty of bacteria in their gut, but their functions are not well studied. To determine their effect on honeybee larvae, the 1-day-old larvae were grafted on to 24-well plates from the comb and artificially reared in the lab. They were treated with penicillin–streptomycin to remove the gut symbiotic bacteria. Then, the 5-day-old larvae and the newly emerged adults were weighted. The developmental periods to pupae and eclosion were investigated, respectively. The bacterial amount, expression of developmental regulation genes (ecrandusp), nutrient metabolism genes (ilp1,ilp2,hex70a,hex70b,hex70c, andhex110), and immunity genes (apidaecin,abaecin,defensin-1, andhymenoptaecin) were determined by qRT-PCR. The result showed that the antibiotics-treated larvae have significantly lower body weights in the 5-day-old larvae and the emerged bees. The expression ofilp2 andhex70cin 5-day-old larvae was down-regulated. Theuspwas down-regulated in 5-day-old larvae, but increased in 7-day-old larvae, which disturbed the normal developmental process and caused the extension of eclosion. Moreover, antibiotics tre