Effects of dietary crude protein levels on development, antioxidant status, and total midgut protease activity of honey bee (Apis mellifera ligustica)

The effects of different levels of dietary crude protein on the development, antioxidant enzymatic activity, and total midgut protease activity of honey bees were investigated in the study. A total of 30 colonies of bees with sister queens were used in the test. Dietary treatments were pure rape pollen (Control) and pollen substitutes (PS) with crude protein (CP) levels at 15%, 20%, 25%, 30%, and 35% (designated as PS15, PS20, PS25, PS30, and PS35), respectively. We compared the effects of these diets on honey bees by measuring diet consumption, bee development (egg hatch, pupation success, and pupal weight), and the protein content of emergent adult bees, their antioxidant status and the activity of their midgut digestive proteases. Bees consumed significantly more (P < 0.001) natural pollen than any PS, and bees fed PS had similar diet consumption over the entire experimental period. However, the total protein intake was varied (P < 0.05). PS with a protein level about 30% was recognized as excellent quality diet for maximum body weight, highest protein content and antioxidant enzymatic activity, and PS with a protein rate about 35% exerted the greatest effect on increasing percentage of hatch and percentage of pupation. All these results indicate that PS appeared to be a valuable proteinaceous food approximated to the pollen, and 30 similar to 35% of dietary protein level was optimal to maintain the colony development.