Two novel venom proteins underlie divergent parasitic strategies between a generalist and a specialist parasite

Parasitoids are ubiquitous in natural ecosystems. Parasitic strategies are highly diverse among parasitoid species, yet their underlying genetic bases are poorly understood. Here, we focus on the divergent adaptation of a specialist and a generalist drosophilid parasitoids. We find that a novel protein (Lar) enables active immune suppression by lysing the host lymph glands, eventually leading to successful parasitism by the generalist. Meanwhile, another novel protein (Warm) contributes to a passive strategy by attaching the laid eggs to the gut and other organs of the host, leading to incomplete encapsulation and helping the specialist escape the host immune response. We find that these diverse parasitic strategies both originated from lateral gene transfer, followed with duplication and specialization, and that they might contribute to the shift in host ranges between parasitoids. Our results increase our understanding of how novel gene functions originate and how they contribute to host adaptation.


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The transcript sequences of Lar and Warm were deposited in GenBank with the accession numbers MT431620 (Lar) and MT439843 (Warm). Genomes and transcriptome sequencing data was deposited in GenBank BioProject under accession numbers PRJNA624738 (Lh) and PRJNA624743 (Lb). The proteome data of the venom fluids was deposited in PeptideAtlas under the accession number PASS01574. The microbiota sequencing data was deposited in GenBank BioProject under the accession number PRJNA629859. The authors declare that all data supporting the findings of this study are available within the paper and its supplementary information files or from the corresponding author upon request. Raw data of Figures 1, 2, 4 and Supplementary Figures 9, 12,13, 16, 24 are provided as a Source Data file. Source data are provided with this paper.
DNA of at least 2000 male wasp adults was extracted for each group. Transcriptional levels of wasp samples were measured per development stage. Approximately 300 VRs of 3-d-old Lh female wasps were collected for LC-MS/MS analysis. Total of 30 wasp adults and 150 wasp midguts were dissected for microbiota sequencing per group. More than 100 host larvae were used to test the wasp oviposition rate for each group. More than 500 hosts were used to test the encapsulation rate, parasitism rate and wasp emergence rate for each group. More than 100 host lymph gland were used to test the lytic percentage for each group. More than 75 host larvae were used to test the wasp egg attaching rate for each group. At least 50 wasps were micro-injected with dsRNA for each gene. 20 animals were used to do the qRT-PCR experiments per group. Apoptosis detection was carried out using at least 30 host larval lymph glands. 40 wasp venom apparatus and the carcass were collected for western blot analysis. At least 20 host larval lymph glands were used for immunohistochemistry per group. These numbers of samples were sufficient to perform a confident data analysis. All the n values are provided in legends and source data.
No data were excluded.
The experiments for detecting the wasp oviposition rate, parasitism rate and egg attaching rate were done at least for three times. The qRT-PCR experiment for detecting RNA interference effeciency of each gene was repeated at least for three times.
The samples for DNA sequencing, transcriptome sequencing, LC-MS, microbiota analysis, western blot and qRT-PCR were all randomly picked. The host larvae were also randomly picked to test the wasp oviposition rate, encapsulation rate, parasitism rate, wasp emergence rate, and wasp egg attaching rate. The Lymph Glands dissected from a certain number of randomly-selected parasitized host larvae for detect the lytic percentage and antibody staining.
Investigators were blinded to group allocation for the quantification of the wasp egg attaching rate.