Influence of pollen and carbohydrate sources on honey bee longevity and physiological factors

The Western honey bee (Apis mellifera) plays a crucial role in global agriculture by pollinating a wide range of crops and maintaining ecosystem biodiversity. However, in recent years, honey bee populations have experienced alarming declines, raising concerns among scientists, farmers, and environmentalists. These declines are attributed to a combination of stressors, including pesticide exposure, habitat loss, climate change, parasitic infestations, and nutritional deficiencies. In this study, we evaluated the effects of different carbohydrate sources (corn syrup and sugar syrup) and pollen types (rapeseed, kiwi, and a mixed pollen) on honey bee longevity and physiological responses. Kaplan–Meier survival analysis revealed that bees fed corn syrup, particularly when combined with mixed pollen (CS-MP), exhibited the highest survival rates. Corn syrup-fed bees also had significantly longer lifespans and lower food consumption compared to those fed sugar syrup, suggesting enhanced nutritional efficiency. Furthermore, bees in the CS-MP group developed larger hypopharyngeal gland (HPG) acini and exhibited the highest relative expression of the vitellogenin gene, indicating superior nutritional benefits. Gut microbiota analysis demonstrated that dietary treatments significantly shaped microbial composition, with a notable increase in Lactobacillus abundance in the mixed pollen groups. Overall, these findings highlight the importance of optimal carbohydrate–pollen combinations in promoting honey bee longevity, gland development, gene expression, and gut microbial health. The results offer practical implications for beekeeping practices aimed at improving colony health and resilience.