Quantification of Hemolymph Proteins as a Fast Method for Testing Protein Diets for Honey Bees (Hymenoptera: Apidae)

Hemolymph protein measurements in honey bees, Apis mellifera L., were used to determine the efficiency of protein diets as pollen substitutes. Groups of 120 newly emerged worker bees were kept in small cages in the laboratory and fed on bee bread or unprocessed pollen (natural protein diets), soybean/yeast or corn meal (alternative protein diets), or a sucrose solution (nonprotein diet), from adult emergence until 6 d later. The protein content in hemolymph was determined in these bees at 0, 2, 4, and 6 d of adult life. Additionally, vitellogenin (a major protein in young adult worker bees) titer was measured through rocket immunoelectrophoresis of the hemolymph of 6-d-old bees. A significant and progressive rise in protein titers was observed from o to the 6th d of adult life in the hemolymph of bees fed on bee bread, soybean/yeast, or pollen. However, a significant protein reduction was recorded in bees fed on corn meal or sucrose only. The protein titer of 6-d-old bees gave the best discrimination between diets. Protein titers were highly correlated with vitellogenin levels in 6-d-old bees, when the different diets were compared. The protein values reflected the quantity and usability of the protein in the diets and not the consumption, which was similar for all protein diets used. Both total protein measurement and vitellogenin level determination proved to be objective methods for comparing the effectiveness of protein diets; however, the former is faster and less expensive and could easily be used for routine analyses.