RNA viruses in parasitoids: Do they shape biological control outcomes?

Abstract: Parasitoids are key elements in biological control programmes, whose success
largely depends on a well-developed arsenal of virulence factors. Although successful
parasitism in certain species depends on the presence of endogenous DNA viruses, limited
information is available regarding the role of exogenous (non-endogenous) viruses. During the last decade, it has become evident that previously overlooked RNA viruses, despite being
ubiquitous in insects, can contribute to the failure or success of parasitism. To address this gap, we characterized the virome of the major greenhouse pest Planococcus citri Risso (Hemiptera: Pseudococcidae) and its parasitoid Anagyrus vladimiri Triapitsyn (Hymenoptera: Encyrtidae). By high-throughput sequencing, we described 13 RNA viruses, including 11 novel species, with four associated exclusively with P. citri, seven with A. vladimiri, and two shared by both species. Remarkably, A. vladimiri transmitted three of its seven associated viruses to P. citri through oviposition. Current research is focused on elucidating the functional role of these viruses in the outcome of parasitism, including their effects on parasitoid fitness, host mortality, and developmental success, with a specific focus on one of the previously uncharacterized viruses. Unravelling these multitrophic associations could improve our understanding of the hidden factors shaping biological control efficiency in greenhouse systems.