A novel cripavirus of an ectoparasitoid wasp increases pupal duration and fecundity of the wasp's Drosophila melanogaster host.

We identified a 9332-nucleotide-long novel picornaviral genome sequence in the transcriptome of an agriculturally important parasitoid wasp (Pachycrepoideus vindemmiae (Rondani, 1875)). The genome of the novel virus, Rondani’s wasp virus 1 (RoWV-1), contains two long open reading frames encoding a nonstructural and a structural protein, respectively, and is 3’-polyadenylated. Phylogenetic analyses firmly place RoWV-1 into the dicistrovirid genus Cripavirus. We detected RoWV-1 in various tissues and life stages of the parasitoid wasp, with the highest virus load measured in the larval digestive tract. We demonstrate that RoWV-1 is transmitted horizontally from infected to uninfected wasps but not vertically to wasp offspring. Comparison of several important biological parameters between the infected and uninfected wasps indicates that RoWV-1 does not have obvious detrimental effects on wasps. We further demonstrate that RoWV-1 also infects Drosophila melanogaster (Meigen, 1830), the hosts of the pupal ectoparasitoid wasps, and thereby increases its pupal developmental duration and fecundity, but decreases the eclosion rate. Together, these results suggest that RoWV-1 may have a potential benefit to the wasp by increasing not only the number of potential wasp hosts but also the developmental time of the hosts to ensure proper development of wasp offspring.