Influence of different pollen diets on the development of hypopharyngeal glands and size of acid gland sacs in caged honey bees (Apis mellifera)

We examined the consumption rate of protein diets in caged and free-flying honey bees, amino acid composition of diets, and diet effects on gland development. The effect of seven different diets (sugar solution only, Feedbee®, Helianthus pollen, Sinapis pollen, Asparagus pollen, Castanea pollen, and mixed pollen diet) on the development of the hypopharyngeal (HPG) and acid glands (AG) was tested in caged honey bees. Caged bees consumed the protein diet mainly at the age of 1–8 days, with the highest consumption rate on day 3. Different diets affected the development of both glands. The acini of HPG attained their maximum size in caged bees at an age of 5 days. Bees fed with Castanea sp., Asparagus sp., or mixed pollen had the largest glands among all test groups of this age. The AG sacs of caged bees grew in size between 5 and 12 days and were at day 18 less affected by different protein diets. Castanea sp. and mixed pollen diets were preferably consumed in free-flying colonies.