Evaluation of protein and amino acid composition of pollen and its use by domestic honey bees (Apis mellifera)

Pollen is the main source of proteins and amino acids for Apis mellifera L. However few studies have evaluated the use of these nutrients by domestic honey bees. This study examined protein content, amino acid profile, and their apparent digestibility of various pollen types foraged by honey bees in an apicultural region of Argentina. To achieve this purpose, bee pollen was collected, identified and separated into monofloral pollen loads which were used to formulate pollen diets with TiO₂ as an inert marker. Crude and soluble protein contents, as well as amino acid profiles, were analyzed in the diets. Subsequently, we conducted three in vitro trials using caged bees fed with these diets. Feces were collected and analyzed for soluble proteins and amino acid profiles. The soluble and crude protein of the diets varied according to their botanical origin, but amino acid profiles were consistent among diets. Caged bees, especially spring bees, used efficiently the protein in the diets (83.6 ± 24.2% apparent digestibility). No significant differences in the apparent digestibility were detected among the 19 amino acids evaluated. This suggests either bees do not selectively absorb specific amino acids from food, or modifications of the amino acids profile by endogenous secretions or gut microbiota activity. These findings contribute to a better understanding of how honey bees utilize dietary proteins, providing valuable information for improving apicultural nutrition strategies.