The effect of microalgae addition and fermentation of pollen substitute diets on the physiological characteristics of honey bees

This study aimed to develop a nutritious and palatable pollen substitute diet for honey bees. Here, in caged-bee experiments, a mixture of microalgae (Chlorella and Spirulina) at concentrations of 5% and 10% was evaluated as a novel nutritional additive to fermented diets. The results showed that the addition of microalgae to the fermented diet considerably improved the diet’s consumption ratio and digestibility, as well as hypopharyngeal gland (HPG) development, total hemolymph protein concentration, total body fat, hindgut weight, bacterial counts, and worker dry thorax weight compared with the traditional pollen substitute and sugar. However, the response varied significantly with the level of microalgae supplementation. In most cases, the fermented diet supplemented with 10% microalgae yielded the best results among the substitute diets. Therefore, based on the results of the present study, we conclude that a fermented diet supplemented with 10% microalgae significantly affects key physiological characteristics associated with the nutritional status of the honey bee (Apis mellifera L.), thereby improving its performance.