A new volvovirus isolate from the Korean two-spotted cricket (Gryllus bimaculatus) and the analysis of its genome

The cricket industry in South Korea has experienced significant annual growth, supported by advanced technology and government programs. These advantages have enabled the insect industry to establish mass rearing methods; however, these methods are vulnerable to epizootic diseases, particularly those caused by entomopathogens. In this study, we collected crickets from various farms and analyzed their virome composition using nine different PCR primer sets for cricket viruses. While volvovirus was not detected at all cricket farms, it was the only virus found. Consequently, the focus of this study was on the genomic analysis and molecular characterization of a novel strain of volvovirus identified in Gryllus bimaculatus in South Korea, designated as GbVVV-KR. The complete genome sequence of GbVVV-KR was obtained through Sanger sequencing using degenerate primers, revealing a circular single-stranded DNA virus with a genome size of 2,515 nucleotides. The genomic analysis showed variations, including single-nucleotide polymorphisms and insertions/deletions, with a notable mutation occurring at the 112th codon (GAA) in ORF3, which resulted in a stop codon (TAA). Additionally, when assessing the prevalence of GbVVV-KR, the virus was detected in 8 out of 11 farms across South Korea, with varying viral loads observed among the farms. This study provides valuable insight into the genetic characteristics, phylogeny and prevalence of GbVVV-KR, and contributes to a broader understanding of entomopathogenic viruses in crickets.