In honey bees, adult longevity is strongly dependent on the quantity of dietary protein ingested after emergence, but relatively little is known about the role played by the protein content of larval diet. In total, 15 colonies of Apis mellifera ligustica Spinola (Hymenoptera: Apidae) bees with sister queens were randomly allocated to one of three groups (five colonies per group), provided with pollen substitutes (PS) with protein concentrations of 15, 25, or 35%, designated as PS15, PS25, and PS35, respectively. In a field experiment, we measured the PS consumption and collected samples for analyzing body protein content and gene expression. On day 29, groups of 50 newly emerged workers from each colony were obtained and confined in cages for measuring survival and longevity. Results showed that bees consumed significantly more PS15 and PS25 than PS35. However, the total protein intake of PS15 was less than that of the others. Increasing the protein available to larvae (PS35) significantly increased total accumulated protein before emergence, adult survival, and longevity. Furthermore, bees fed PS25 or PS35 tended to have higher mRNA levels for genes encoding antioxidant enzymes, providing a potential physiological mechanism for observed survival differences among the three dietary treatments. We conclude that protein content in larval diet could positively influence worker longevity likely because of the increased related antioxidant gene expression.

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Effects of dietary crude protein levels on development, antioxidant status, and total midgut protease activity of honey bee (Apis mellifera ligustica).Abstract -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∼35% of dietary protein level was optimal to maintain the colony development.Apis mellifera ligustica / dietary crude protein levels / development / antioxidant status / total midgut protease activity

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