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Herbivorous insects harbor a variety of insect-specific viruses (ISVs) some of which are considered to be valuable biological agents for potential applications in biological defense and control strategies. Leaf beetles with chewing mouthparts are particularly known for their capacity to disrupt plant tissue while feeding, often creating openings that can act as entry points for plant pathogens. In this study, we have identified two new negative-sense RNA viruses infecting the leaf beetle Aulacophora indica, an important member of the Chrysomelidae family. These recently discovered viruses belong to the viral families Nyamiviridae and Chuviridae and have been preliminarily named Aulacophora indica nyami-like virus 1 (AINlV1) and Aulacophora indica chu-like virus 1 (AIClV1), respectively. The complete genomic sequences of these viruses were obtained using rapid amplification of cDNA ends (RACE) techniques. Detailed analysis of their genomic structures has confirmed their similarity to other members within their respective families. Furthermore, analysis of virus-derived small interfering RNA (vsiRNA) demonstrated a high abundance and typical vsiRNA pattern of AINlV1 and AIClV1, offering substantial evidence to support their classification as ISVs. This research enhances our understanding of viral diversity within insects.

Agricultural insects play a crucial role in transmitting plant viruses and host a considerable number of insect-specific viruses (ISVs). Among these insects, the white-backed planthoppers (WBPH; Sogatella furcifera, Hemiptera: Delphacidae) are noteworthy rice pests and are responsible for disseminating the southern rice black-streaked dwarf virus (SRBSDV), a significant rice virus. In this study, we analyzed WBPH transcriptome data from public sources and identified three novel viruses. These newly discovered viruses belong to the plant-associated viral family Solemoviridae and were tentatively named Sogatella furcifera solemo-like virus 1-3 (SFSolV1-3). Among them, SFSolV1 exhibited a prevalent existence in different laboratory populations, and its complete genome sequence was obtained using rapid amplification of cDNA ends (RACE) approaches. To investigate the antiviral RNA interference (RNAi) response in WBPH, we conducted an analysis of virus-derived small interfering RNAs (vsiRNAs). The vsiRNAs of SFSolV1 and -2 exhibited typical patterns associated with the host’s siRNA-mediated antiviral immunity, with a preference for 21- and 22-nt vsiRNAs derived equally from both the sense and antisense genomic strands. Furthermore, we examined SFSolV1 infection and distribution in WBPH, revealing a significantly higher viral load of SFSolV1 in nymphs’ hemolymph compared to other tissues. Additionally, in adult insects, SFSolV1 exhibited higher abundance in male adults than in female adults.

A large number of RNA viruses have been discovered in most insect orders using high-throughput sequencing (HTS) and advanced bioinformatics methods. In this study, an RNA virome of the grasshopper was systematically identified in Atractomorpha sinensis (Orthoptera: Pyrgomorphidae), an important agricultural pest known as the pink-winged grasshopper. These insect viruses were classified as the nege-like virus, iflavirus, ollusvirus, and chu-like virus using HTS and phylogenetic analyses. Meanwhile, the full sequences of four novel RNA viruses were obtained with RACE and named Atractomorpha sinensis nege-like virus 1 (ASNV1), Atractomorpha sinensis iflavirus 1 (ASIV1), Atractomorpha sinensis ollusvirus 1 (ASOV1), and Atractomorpha sinensis chu-like virus 1 (ASCV1), respectively. Moreover, the analysis of virus-derived small interfering RNAs showed that most of the RNA viruses were targeted by the host antiviral RNA interference pathway. Moreover, our results provide a comprehensive analysis on the RNA virome of A. sinensis.

Insect-specific viruses (ISV) are one of the most promising agents for the biological control of insects. The green leafhopper, Cicadella viridis (Linnaeus), is an significant pest in agriculture, and causes economic losses to fruit trees, willows, and field crops. As a representative species of the large family Cicadellidae, ISVs in C. viridis have never been studied, to date. In this study, the full genome sequences of two ISVs, named Cicadella viridis iflavirus1 (CvIfV1), and Cicadella viridis nido-like virus 1 (CvNiLV1), were revealed using a metatranscriptomic approach. A homology search and phylogenetic analysis indicated that CvIfV1 is a new member in the family Iflaviridae (genus Iflavirus) with a typical iflavirus genome organization, whereas CvNiLV1 belongs to the unclassified clade/family of the order Nidovirales. In addition, analysis of virus-derived small interfering RNAs (vsiRNAs) was performed to investigate the antiviral RNA interference (RNAi) response of C. viridis. The vsiRNAs exhibit typical patterns produced by host siRNA-mediated antiviral immunity, including a preference of 21-nt vsiRNAs derived equally from the sense and antisense genomic strands, and a strong A/U bias in the 5′-terminus of the viral genomes. Our study provides valuable information for ISVs in leafhoppers for the first time, which might prove useful in the control of C. viridis in future.