Evidence for an ichnovirus machinery in parasitoids of coleopteran larvae

Bathyplectes spp. are ichneumonid solitary larval parasitoids of the alfalfa weevil which have been classified in the subfamily Campopleginae and which harbor atypical virus particles. Despite the morphological differences between Bathyplectes spp. particles and the polydnaviruses carried by a number of related campoplegine species, called ichnoviruses, the process by which they are produced is very similar to that of ichnoviruses. To address the question of the nature and origin of these atypical particles, the Bathyplectes anurus ovary transcriptome has been analyzed. We found a number of highly expressed transcripts displaying similarities with genes belonging to the machinery involved in the production of ichnovirus particles. In addition, transcripts with similarities with repeat-element genes, which are characteristic of the packaged campoplegine ichnovirus genome were identified. Altogether, our results provide evidence that Bathyplectes particles are related to ichnoviruses.