A rare, evolutionarily conserved venom protein benefits endoparasitism across parasitoids.

Although many venom proteins and other parasitic effectors have been identified in various specific systems of parasitoids, key elements that contribute to parasitic success across a broad range of taxa remain largely unexplored. Here, we focus on Leptopilina and conduct a large-scale, multi-omics study to explore common venom proteins for these drosophilid parasitoids. We find that this genus has undergone extensive chromosome rearrangements and a rapid turnover of venom gene repertoires between species. Interestingly, we identified a lineage-specific venom lipase, Leptopilina-specific venom lipase (LVL), as a rare venom protein that is subject to evolutionary constraint and recruited by all Leptopilina species. Functional genetics studies on LVL reveal its critical role in hydrolyzing host lipids under acidic conditions, which in turn ensures the nutrition supply for the embryonic development of parasitoids. Our study provides a paradigm to characterize adaptive effectors across diverse insects and highlights the importance of host lipid utilization in the parasitization of parasitoids.