Discovery of new endogenous viral elements in campoplegine wasps (Ichneumonidae, Campopleginae, Campoplex) suggests a widespread nudivirus domestication event

Viral endogenization is a widespread phenomenon that generally results in non-functional viral elements. In parasitoid wasps, nudiviruses have been involved in three independent domestication events and play a key role in parasitism success. In Campopleginae (Ichneumonidae), endogenized ichnovirus presence is widespread, with the exception of Venturia canescens (Ichneumonidae Campopleginae), which is known to harbour an endogenous nudivirus that enables the wasp to produce Virus-Like-Particles (VLPs). So far, in Campopleginae, the nudivirus endogenization event was an isolated case restricted to V. canescens. Using third generation sequencing technologies, microscopy and mass spectrometry, we described new cases of domesticated nudiviruses in campoplegine wasps of the genus Campoplex. We found endogenized viruses in Campoplex genomes which belong to the Alphanudivrius genus and derive from the same endogenization event as the virus found in V. canescens, suggesting that this integration event could be much more widespread in Campopleginae than previously thought. These nudiviruses are organised in highly conserved clusters, but this organisation appears to have changed relatively to free viruses during the domestication process. We showed that Campoplex capitator produces in its ovaries VLPs that are similar morphologically to V. canescens VLPs, with almost the same protein content, except for a strikingly different virulence proteins, a sign of different evolutionary paths taken to respond to distinct evolutive pressure. While ichnovirus remnants have been previously found in V. canescens, no trace of ichnovirus could be detected in Campoplex genomes, meaning that the evolutionary history of viral integrations in Campopleginae is more complex than previously imagined. ### Competing Interest Statement The authors have declared no competing interest.