A novel chuvirus from the southern green stink bug (Nezara viridula) was identi ed by RNA sequencing in this study, which was named "Nbu southern green stink bug chuvirus-1" (NbuSGSBV-1). The complete genome sequence of NbuSGSBV-1 consisted of 11,375 nucleotides, which was con rmed to be a circular form by 'around-the-genome' reverse transcription polymerase chain reaction (RT-PCR) and sanger sequencing. Furthermore, three open reading frames (ORFs) were predicted in the NbuSGSBV-1 genome, including a large polymerase protein (L protein), a glycoprotein (G protein) and a nucleocapsid protein (N protein). Thereafter, a phylogenetic tree was constructed based on the RNA-dependent RNA polymerase amino acid sequences of all the currently available viruses in the family Chuviridae. As a result, NbuSGSBV-1 was clustered together with Sanya chuvirus 2 and Hubei odonate virus 11, indicating that NbuSGSBV-1 might belong to the genus Odonatavirus. Meanwhile, motif prediction results revealed ve conserved sites among the L proteins of NbuSGSBV-1 and its homologous chiviruses. Moreover, the high abundance and typical characteristics of the NbuSGSBV-1-derived small interfering RNAs suggested the active replication of NbuSGSBV-1 in the host insect. To the best of our knowledge, this is the rst report of a chuvirus identi ed from the insect family Pentatomidae. The discovery and characterization of NbuSGSBV-1 will help to understand the diversity of chuviruses in insects. Full TextWith the advancement of next-generation sequencing (NGS) technology and metagenomic analysis in recent years, a growing number of novel viruses have been discovered and identi ed [1,2]. Most of them are discovered from arthropods such as insects, arachnids, and chilopoda [2,3]. As a result, arthropods are assumed as the primary store of viral genetic variety, which may play an important role in viral evolution [2,4]. As the number of novel viruses increases dramatically, new families of viruses are gradually divided. For instance, the family Chuviridae was de ned in 2015, which belongs to the order Jingchuvirales, class Monjiviricetes [2]. Most of the viruses in the family Chuviridae were discovered in the ancient Chinese region called Chu, which referred to the middle and lower reaches of the Yangtze River at that time [2,5]. The phylogenetic diversity of chuviruses is between those of segmented and nonsegmented viruses, and their genome structures are also diverse, including unsegmented, bi-segmented, and a circular form [2,4,5]. Typically, the circular structure of Chuviridae is distinct from the pseudocircular structure of some other negative-sense RNA viruses like the families Buniaviridae and Orthomyxoviridae. The genome sequences of linear chuviruses are composed of a glycoprotein (G), a nucleoprotein (N) and a polymere (L) genes, while those of circular chuviruses are generally considered in the order L-(G)-N (displayed in a linear form), such as Bole Tick Virus 3 (GenBank NO. NC_028259.1). It is also reported that G gene is probably lost duri...

Background: The brown planthopper (BPH) is one of the most destructive agricultural pests in Asia. RNA interference (RNAi)mediated pest management has been under development for years, and the selection of appropriate target genes is important for pest-targeted RNAi. C-type lectins (CTLs) are a class of genes that perform a variety of functions, such as the regulation of growth and development.Results: A CTL-S protein named Nllet1, containing a single calcium ion (Ca 2+ )-dependent carbohydrate-binding domain (CRD) with a conserved triplet motif QPD was identified and functionally characterized in BPH. Expression profiles at both the transcriptional and translational levels show that Nllet1 accumulates during the serosal cuticle (SC) formation period. Immunofluorescence and immunogold labeling further demonstrated that Nllet1 is located in the serosal endocuticle (en-SC). Maternal RNAi-mediated silencing of Nllet1 disrupted the SC structure, accompanied by a loss of the outward barrier and 100% embryo mortality. Injection of 10 ng dsNllet1 or dsNllet1' per female adult BPH resulted in a total failure of egg hatching. Conclusion:Nllet1 is essential for SC formation and embryonic development in BPH, which helps us understand the important roles of CTL-Ss. Additionally, BPH eggs show high sensitivity to the depletion of Nllet1. This study indicates that Nllet1 is a promising candidate gene that can be used to develop RNAi-based control strategies at the BPH egg stage, and it can also be used as a target for developing novel ovicides.

A novel chuvirus from the southern green stink bug (Nezara viridula) was identified by RNA sequencing in this study, which was named "Nbu southern green stink bug chuvirus-1" (NbuSGSBV-1). The complete genome sequence of NbuSGSBV-1 consisted of 11,375 nucleotides, which was confirmed to be a circular form by ‘around-the-genome’ reverse transcription polymerase chain reaction (RT-PCR) and sanger sequencing. Furthermore, three open reading frames (ORFs) were predicted in the NbuSGSBV-1 genome, including a large polymerase protein (L protein), a glycoprotein (G protein) and a nucleocapsid protein (N protein). Thereafter, a phylogenetic tree was constructed based on the RNA-dependent RNA polymerase amino acid sequences of all the currently available viruses in the family Chuviridae. As a result, NbuSGSBV-1 was clustered together with Sanya chuvirus 2 and Hubei odonate virus 11, indicating that NbuSGSBV-1 might belong to the genus Odonatavirus. Meanwhile, motif prediction results revealed five conserved sites among the L proteins of NbuSGSBV-1 and its homologous chiviruses. Moreover, the high abundance and typical characteristics of the NbuSGSBV-1-derived small interfering RNAs suggested the active replication of NbuSGSBV-1 in the host insect. To the best of our knowledge, this is the first report of a chuvirus identified from the insect family Pentatomidae. The discovery and characterization of NbuSGSBV-1 will help to understand the diversity of chuviruses in insects.

Apolipoprotein D (ApoD), a member of the lipocalin superfamily of proteins, is involved in lipid transport and stress resistance. Whereas only a single copy of the ApoD gene is found in humans and some other vertebrates, there are typically several ApoD‐like genes in insects. To date, there have been relatively few studies that have examined the evolution and functional differentiation of ApoD‐like genes in insects, particularly hemi‐metabolous insects. In this study, we identified 10 ApoD‐like genes (NlApoD1−10) with distinct spatiotemporal expression patterns in Nilaparvata lugens (BPH), which is an important pest of rice. NlApoD1−10 were found to be distributed on 3 chromosomes in a tandem array of NlApoD1/2, NlApoD3−5, and NlApoD7/8, and show sequence and gene structural divergence in the coding regions, indicating that multiple gene duplication events occurred during evolution. Phylogenetic analysis revealed that NlApoD1−10 can be clustered into 5 clades, with NlApoD3−5 and NlApoD7/8 potentially evolving exclusively in the Delphacidae family. Functional screening using an RNA interference approach revealed that only NlApoD2 was essential for BPH development and survival, whereas NlApoD4/5 are highly expressed in testes, and might play roles in reproduction. Moreover, stress response analysis revealed that NlApoD3−5/9, NlApoD3−5, and NlApoD9 were up‐regulated after treatment with lipopolysaccharide, H2O2, and ultraviolet‐C, respectively, indicating their potential roles in stress resistance.