A new nucleopolyhedrovirus isolated from a laboratory population of Cydia pomonella exhibits excellent biological activity.

While naturally occurring insect-pathogenic viruses are valuable resources utilized as biocontrol agents, the covert viruses maintained in laboratory insect populations have been comparatively less explored. In this study, we report the isolation and characterization of a novel nucleopolyhedrovirus, CypoNPV, from a laboratory population of Cydia pomonella. Whole-genome sequencing revealed a genome size of 112,909 bp for CypoNPV, exhibiting close phylogenetic proximity to Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV). Comparative life-history analyses of populations designated as normal-viral (NV), low-viral (LV), and virus-free (VF) demonstrated that latent CypoNPV infection exerted no significant detrimental impact on population parameters. Bioassays indicated that proliferated CypoNPV maintained high pathogenicity toward neonate C. pomonella larvae. Subsequent two-season field evaluations corroborated its potent efficacy, achieving levels comparable to the synthetic pyrethroid insecticide lambda-cyhalothrin. Moreover, CypoNPV exhibited considerable thermostability, albeit with diminished resistance to ultraviolet (UV) radiation. Collectively, these findings offer a comprehensive genomic and biological profile of CypoNPV, positing that covert infections within laboratory populations may constitute a promising source for the discovery and application of pathogenic viruses for pest biological control.