Diverse pollen nutrition can improve the development of solitary bees but does not mitigate negative pesticide impacts

Effects of Three Different Bee Pollen on Digestion, Immunity, Antioxidant Capacity, and Gut Microbes in Apis mellifera

The nutritional value of pollen for honeybees varies significantly depending on its source. This study examines the nutrient composition of three types of bee-collected pollen-Maize bee-collected pollen (MBP), Lotus bee-collected pollen (LBP), and Sunflower bee-collected pollen (SBP)-and their effects on honeybee digestion, immunity, and gut microbiota. Nutritional analysis revealed no significant differences in moisture, protein, and carbohydrate content among the three pollen types. However, sunflower bee-collected pollen exhibited a significantly lower crude fat content than maize bee-collected pollen and lotus bee-collected pollen, while lotus bee-collected pollen had a significantly higher crude ash content than the other pollen types. Additionally, notable differences in amino acid composition were observed across the three pollen types. Feeding assays demonstrated that honeybees consumed significantly more sunflower bee-collected pollen than maize bee-collected pollen or lotus bee-collected pollen. Honeybees fed sunflower bee-collected pollen exhibited reduced lipid deposition, enhanced immune enzyme activity, and increased expression of immune-related genes. Protein digestibility was highest in honeybees fed lotus bee-collected pollen, whereas protease and lipase activities were significantly lower in those consuming sunflower bee-collected pollen. Notably, honeybees fed sunflower bee-collected pollen had thinner midgut intestinal walls. Furthermore, the microbial structure of the honeybee gut was altered depending on the type of different pollen. In summary, honeybees had the worst digestibility of Sunflower bee-collected pollen; sunflower bee pollen had a greater effect on antioxidant and immune functions, and intestinal flora of honeybees. These findings underscore the influence of different types of pollen on honeybee nutrition, immunity, and gut microbiota, offering a foundation for optimizing pollen diets to support honeybee health.

Age-dependent hypopharyngeal gland size and protein content of stingless bee workers, Tetragonula pagdeni

Eusocial insects, such as stingless bees (Meliponini), depend on division of labour, overlapping generations, and collaborative brood care to ensure the functionality and success of their colony. Female workers transition through a range of age-specific tasks during their lifespan (i.e., age-polyethism) and play a central role in the success of a colony. These age-specific tasks (e.g., brood care or foraging) often closely coincide with key physiological changes necessary to ensure optimal performance. However, our understanding of how nutrition, age, and polyethism may affect the development of such physiological traits in stingless bees remains limited. Here we show that pollen consumption and age-polyethism govern hypopharyngeal gland (HPG) acini size and protein content in Tetragonula pagdeni. By conducting a controlled laboratory experiment we monitored the effect of pollen consumption on worker bee survival as well as assessed how a pollen diet and age affected their HPG acini width and protein content. Further, we sampled nurses and foragers from field colonies to measure the effect of age-polyethism on HPG acini width. We found that pollen consumption enhanced survival and led to increased HPG acini width and protein content and that HPG acini were as expected largest in nurse bees. Our findings highlight the beneficial effects of an adequate diet for physiological development and health in stingless bees and reveal that age-polyethism is the key factor governing HPG size in worker bees. As HPGs are imperative for collaborative brood care-an essential component of eusociality-the data provide a foundation for future studies to investigate the impact of potential environmental stressors on a critical physiological trait in stingless bees which may serve as a proxy to understand the effects at the colony level.