Nasonia vitripennis Venom Y Knockdown Assayed in flesh fly Neobellieria bullata

Venom of the parasitoid wasp Nasonia vitripennis changes the metabolism and gene expression in its fly host Sarcophaga bullata to induce developmental arrest, suppression of the immune response, and various other venom effects. Yet, the venom of ectoparasitoid wasps, as a cocktail of proteins and small molecules, has not been fully characterized. A major component of N. vitripennis venom is an uncharacterized, high-expressing protein referred to as Venom Y. We found that Venom Y is a relatively young gene with no homologs found in any species >15MY diverged from N. vitripennis. Venom Y has duplicated to form two distinct paralog groups and a copy of Venom Y has been recruited as a venom protein in at least five wasp species, although which paralog is recruited varies. Functional analysis using RNAi knock downs found that Venom Y affects detoxification and immunity genes in envenomated fly hosts. Many of these genes are fat body specific, suggesting that Venom Y may have a targeted effect on fat body tissue. We also show that Venom Y reduces the changes in expression of some host genes caused by other venom components, consistent with the hypothesis that some venom proteins may mitigate negative effects of others. This study contributes to elucidating parasitoid venom and demonstrates the utility of RNAi knockdown for investigating venom protein function in the context of the whole venom cocktail.