Influence of bee pollen supplement on health and immunity of the honeybee Apis mellifera L

Abstract In the current study, the effect of a supplemented diet (artificial protein cake) administered during autumn and winter was evaluated. The histological examination of the midgut tissue was performed. Measured parameters included gene expression of antimicrobial peptides (defensin-1, abaecin, and hymenoptaecin), activities of antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), and glutathione (GSH). In addition, lipid peroxidation (LPO), total protein carbonyl content ( TPC), vitellogenin (Vg), glucose oxidase activity, and total polyphenols were measured in newly emerged, nurse, and forager worker bees from both supplemented and control colonies. Colonies that did not receive dietary supplementation served as controls. The histological analysis revealed morphological alterations in the midgut cells of treated bees. On the other hand, there are noticeable increases in the gene expression of antimicrobial peptides, antioxidants, glucose oxidase, and total polyphenols content in colonies fed the supplemented diet compared with control colonies. In contrast, Vg and LPO levels were lower in the treatment group than in the control group. Generally, there was a clear improvement in the gene expression of antioxidant enzymes and antimicrobial peptides in bee colonies that received a supplemental diet compared to control colonies. The honeybee workers supplemented with the artificial diet may possess mechanisms that reduce oxidative stress. Together, the results indicate that supplemental feeding can enhance colony health during the overwintering period, a time marked by increased colony losses. However, this practice appears to impact the physiological state of the workers’ midgut. In conclusion, it is crucial to feed honeybees diets that contain the essential elements required to maintain bee health.