Foraging effort outpaces foraging precision under amino acid deficiency in Apis mellifera (Hymenoptera: Apidae)

The European honey bee (Apis mellifera Linnaeus) is the most widely used commercial pollinator and relies on pollen to obtain essential amino acids (EAAs) required for development. Because modern agriculture often restricts honey bees to nutritionally limited monocultures, colonies may experience EAA deficiencies that compromise health. While honey bee colonies are known to increase pollen foraging in response to reduced stores, it remains unclear whether foragers can compensate for dietary imbalances by selecting higher-quality pollen in field-relevant conditions. We raised colonies on diets with either complete or deficient EAA profiles and allowed them to forage freely in a natural environment while tracking pollen foraging effort and analyzing the nutritional content of bee-collected pollen. Colonies raised on EAA-deficient diets increased pollen foraging, indicating a behavioral response to nutritional stress. However, the nutritional quality of bee-collected pollen did not differ among treatments, suggesting that foragers did not compensate by selecting pollen with higher crude protein content. Our results suggest that colonies respond to EAA limitation by increasing foraging effort, but foragers may lack the capacity to assess or respond to pollen quality at the level of crude protein. This finding highlights a potential disconnect between colony nutritional needs and individual foraging behavior, and it raises broader questions about how honey bees regulate nutrient intake in variable landscapes.