Improving pollen substitutes to maintain development and hemolymph parameters of honey bees (Apis mellifera L.) during pollen dearth periods

To enhance the performance of honey bee colonies and to improve the physiological characteristics of honey bee workers in late winter and early spring (dearth period) in Assiut region, Upper Egypt-three pollen substitutes rich in protein and available in the local market were used and compared with bee bread as a control. The pollen substitutes were administrated at 7-day intervals for 15 wk, from December 2018 to March 2019. The rate of food consumption, sealed brood areas, bee population size, and characteristics of hemolymph of honey bee individuals were measured. Stored bee bread was the best protein source for developing honey bee colonies, continued with date syrup, recording the highest sealed brood areas compared with the rest of the diets. All hemolymph parameters under substitute feeding conditions were less than those determined under control conditions (bee bread), and the numbers of spring bees were more than those of winter bees. Total soluble solids (TSS), total hemolymph count (THC), differential hemolymph count (DHC), and hemolymph protein concentration (HPC) differed significantly among the experimental treatments with a significant superiority of date syrup (diet 3) over the others. It can be concluded that the date syrup was more suitable for honey bee colonies which was more favorable than traditional pollen substitute and improved physiological status of honey bee individuals during pollen scarcity periods. So under Upper Egypt conditions, pollen substitute feeding especially date syrup during the winter-early spring period under pollen scarcity helped honey bee colonies to be developed in the early spring seasons.