Insect lipophorin and vertebrate lipoproteins support larval development of the endoparasitoid Venturia canescens (Hymenoptera: Ichneumonidae) as dietary lipid sources

We previously reported that lipophorin, an insect lipoprotein, is essential for in vitro development of the larval endoparasitoid Venturia canescens from the 1st larval instar to the 2nd instar. In this study, we compared the effect of various lipoproteins from insects and vertebrates to clarify whether the growth promotion effect of lipophorin is caused by its lipid moiety. As well as the permissive host (the greater wax moth) lipophorin, lipoproteins from a nonpermissive host (the silkworm) and vertebrates (chicken and human) also promoted V. canescens development to the 2nd larval instar, suggesting that essential factors for the first larval ecdysis are ubiquitous in a wide range of animals. When total lipids from the permissive host were emulsified in a lipoprotein-free medium with multilaminar vesicles of phosphatidylcholine (liposome), V. canescens larvae underwent ecdysis in the medium. In contrast, lipophorin lipid-depleted by lipase treatment promoted larval growth less than intact lipophorin. These results indicated that the growth-promotion effect of lipophorin is mainly due to the lipid moiety of lipophorin.