Global climate change, intensive agriculture, and anthropogenic pollution adversely affect flowering plants and the vitality of bee colonies. In nutritional stress conditions, bees deplete the food reserves of their fat body to sustain colony life. Beekeepers play a critical role by providing supplemental nutrient solutions. This study examines the effects of various sugar syrups on the fat body development of worker bees (Apis mellifera macedonica). The colonies were divided into one control group and five experimental groups: one fed with 1:1 sugar/water syrup, one with 2:1 sugar/water syrup, one with inverted syrup (Apiinvert), one with HFCS (high-fructose corn syrup) (Isosweet), and one with 1:1 honey/water syrup. Fat body development was assessed through meticulous dissection, and the degrees of development were documented using a USB digital microscope (Bresser). The results indicate significant seasonal variations in fat body development, with winter depletion and recovery influenced by supplemental feeding. Apiinvert and honey/water syrup promoted higher fat body stages, while Isosweet led to elevated fifth degrees of development but raised concerns about potential toxicity due to the hydroxymethylfurfural (HMF) formation of improperly stored syrups. This study concludes that adequate supplemental feeding with easily digestible sugars is critical for promoting fat body development, enhancing winter survival, and ensuring overall colony health. These findings provide practical guidance for beekeepers to optimize feeding strategies and support resilient bee colonies.

The supplementary feeding of bee colonies under conditions of limited natural food sources is essential for maintaining their health and productivity. Pollen is a major source of protein for bees, collected during plant flowering. Its absence negatively affects the secretory activity of the hypopharyngeal glands (HPGs) in young nurse bees. This study aimed to assess the effect of different protein sources provided during the spring period on the development of HPGs in worker bees. An experiment was conducted with 28 bee colonies divided into seven groups of four colonies each—one control and six experimental. The colonies were fed soy isolate (Glycine max), brewer’s yeast (Saccharomyces cerevisiae), spirulina (Arthrospira platensis), pea protein (Pisum sativum), and bee pollen (a mixture of pollens from various plant species). The results confirmed the critical role of pollen, as 40% of bees in the pollen-fed group exhibited HPGs at grade 4. The group supplemented with spirulina showed similar results (35.8%), indicating its potential as an alternative protein source. These findings highlight the importance of proper protein supplementation and suggest that spirulina could serve as a promising substitute for pollen in early spring feeding to support colony development.