Lipogenesis in an adult parasitic wasp.

The goal of this study was to determine the extent of lipogenesis in the parasitoid Eupelmus vuilletti (Hymenoptera: Eupelmidae). Carbohydrate and lipid metabolism were followed in glucose-fed and starved females over 3 days. Fed females increased their glycogen level, while maintaining their lipid level. Starved females used most of their glycogen, while maintaining their lipid level too. Thus, females either use exclusively sugars to preserve their lipid reserves, or maintained a steady renewal of lipids through lipogenesis. The incorporation of radioactively marked glucose into lipids showed however that lipogenesis did not occur at a sufficient level to increase lipid reserves and to compensate for lipid use. This result has important implications for understanding nutrients allocation strategy in this species as the amount of lipids is almost totally fixed upon the emergence. From an evolutionary perspective, we call for detailed physiological studies of lipogenesis in a wide range of adult hymenopterans, as the absence of lipogenesis could be common to all of Aculatea.