Development of the Hypopharyngeal Glands of Worker Bees (Apis mellifera L.) When Fed Different Protein Sources During the Spring Period

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 (<i>Glycine max</i>), brewer's yeast (<i>Saccharomyces cerevisiae</i>), spirulina (<i>Arthrospira platensis</i>), pea protein (<i>Pisum sativum</i>), 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.