| Dietary crude protein plays a crucial role during the development of honey bee. Twoexperiments were conducted to investigate the effects of different levels of dietary crudeprotein on the development and relative gene expression of honey bees (Apis mellifera).Besides, in order to determine the optimal level of larva and adult, as a guideline forapiculture, we conducted the field study and we compared these effects of pollen substituteswith those of pollen.Exp.1The objective of the experiment was to study the effects of food protein quality onbee development and longevity. A total of15colonies of bees with sister queens from thesame breeding line were randomly allocated to3groups (5colonies per group). All bees wereadapted to pollen substitutes (PS) containing a low (15%, LP), medium (25%, MP), or high(35%, HP) level (dry matter basis) of crude protein. We measured the weight, body proteincontent and the expression of gene proPO related to cuticle development during eachdevelopment stage. Furthermore, we analyzed the effects of larval food quality on adultlongevity and relative antioxidant gene expression of all development stage. The results ofthis experiment indicated：The weight of L5and W0were significantly varied (P <0.05)among treatment and bees fed LP showed the lowest weight (P <0.05). Diet quality had asignificant impact on body protein content of all development stage and those of LP were thelowest (P <0.05). During the7days after emergence, the ingested dietary protein was mainlyused for hypopharyngeal gland and the protein content in hemolymph is relatively lower. Theadult fed LP in the larval period suffered a short longevity and low expression of Cu/ZnSod,MnSod, Cat and Gst-1of all development stage. Besides, inadequate dietary protein also led toa low expression of proPO.Exp.2In order to determine the optimal dietary crude protein level for honey bee,30colonies of bees with sister queens from the same breeding line were randomly allocated to6groups (5colonies per group). Dietary treatments were pure rape pollen (Control) and pollensubstitutes (PS) with crude protein (CP) levels at15%,20%,25%,30%, and35%(designatedas PS15, PS20, PS25, PS30, and PS35), respectively. We compared the effects of these dietson honey bees by measuring population of colony, bee development (egg hatch, pupation success etc.), and protein content of larva and newly emerged workers as well as theirantioxidant status. All those parameters are used to estimate the optimal level of dietaryprotein. The result of this experiment indicated: Bees consumed significantly more (P <0.001)natural pollen than any PS. In contrast, the activity of midgut digestive protease of bees raisedin Control group was lower than PS30and PS35(P <0.05). PS with a protein rate about35%exerted the greatest effect on increasing percentage of hatch and percentage of pupation, andPS30appeared to contain the highest (P <0.05) body weight, protein content and antioxidantenzymatic activity of larva or newly emerged worker, while PS15suffered a poordevelopment status.All these results indicate: Dietary crude protein level has a great effect on developmentand longevity of honey bee and insufficient dietary protein will lead to a poor developmentstate and short lifespan. The required quantity of dietary protein was varied between larvaland adult stage. The dietary protein content, which was less than25%, was insufficient forlarva and30%-35%was recognized as excellent quality diet for maximum body weight,highest protein content and antioxidant enzymatic activity. As for adult, PS with a proteinlevel higher than20%is basically adequate for adult and30%is optimal. |
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