Small Brown Planthopper Research Articles

Threonyl-tRNA synthetase gene, a potential target for RNAi-based control of three rice planthoppers.

RNA interference (RNAi) has potential as a new strategy for pest control. However, the current overemphasis on the control of a single pest increased control costs. The aim of this study was to find a green method of controlling several pests without affecting the natural enemies with a single target gene. One possible RNAi target is the threonyl-tRNA synthetase (ThrRS), which is conserved and plays a significant role in protein biosynthesis. In this study, one threonyl-tRNA synthetase gene (NlthrS) was identified from the brown planthopper (Nilaparvata lugens). Spatio-temporal expression pattern analysis showed that NlthrS was highly expressed in the ovary, late embryogenesis, nymphs and female adults. In addition, RNAi-mediated knockdown of NlthrS caused 85.6% nymph mortality, 100% female infertility, molting disorder, extended nymph duration and shortened adult longevity. Target-specific results were obtained when dsNlthrS was used to interfere with the whiteback planthopper (Sogatella furcifera), small brown planthopper (Laodelphax striatellus), zig-zag winged leafhopper (Inazuma dorsalis) and their natural enemy (green mirid bug, Cyrtorhinus lividipennis). In addition, dsNlthrS could cause high mortalities of three species of planthoppers (85.6-100%), while only dsNlthrS-1 led to the death (97.3%) of I. dorsalis that was not affected by dsNlthrS-2. Furthermore, neither dsNlthrS-1 nor dsNlthrS-2 could influence the survival of C. lividipennis. The results reveal the biological functions of ThrRS in N. lugens in addtion toits protein synthesis, deepening our understanding of tRNA synthase in insects and providing a new method for the control of several rice pests via one dsRNA design. © 2022 Society of Chemical Industry.

Interaction between endogenous microRNAs and virus-derived small RNAs controls viral replication in insect vectors.

MicroRNAs (miRNAs) play an important role in resisting virus infection in insects. Viruses are recognized by insect RNA interference systems, which generate virus-derived small RNAs (vsRNAs). To date, it is unclear whether viruses employ vsRNAs to regulate the expression of endogenous miRNAs. We previously found that miR-263a facilitated the proliferation of rice stripe virus (RSV) in the insect vector small brown planthopper. However, miR-263a was significantly downregulated by RSV. Here, we deciphered the regulatory mechanisms of RSV on miR-263a expression. The promoter region of miR-263a was characterized, and the transcription factor YY1 was found to negatively regulate the transcription of miR-263a. The nucleocapsid protein of RSV promoted the inhibitory effect of YY1 on miR-263a transcription by reducing the binding ability of RNA polymerase II to the promoter of miR-263a. Moreover, an RSV-derived small RNA, vsR-3397, downregulated miR-263a transcription by directly targeting the promoter region with partial sequence complementarity. The reduction in miR-263a suppressed RSV replication and was beneficial for maintaining a tolerable accumulation level of RSV in insect vectors. This dual regulation mechanism reflects an ingenious adaptation strategy of viruses to their insect vectors.

Structural insights into the interaction between gabazine (SR-95531) and Laodelphax striatellus GABA receptors.

γ-Aminobutyric acid receptors (GABARs) mediate fast inhibitory neurotransmission and are targets for insecticides. GABARs are composed of five subunits, the composition of which dictates the pharmacological characteristics of GABARs. Both competitive and noncompetitive GABAR antagonists can be used as insecticides. Gabazine is a potent competitive antagonist of mammalian α1β2γ2 GABARs; however, it is less potent against insect GABARs. To explore how gabazine interacts with GABARs, we examined whether the sensitivity of the small brown planthopper (Laodelphax striatellus) RDL GABAR (LsRDLR) to gabazine is increased when its amino acid residues are substituted with α1β2γ2 GABAR residues. In the results, two of the generated mutants showed enhanced gabazine sensitivity. Docking simulations of gabazine using LsRDLR homology models and an α1β2γ2 GABAR cryo-EM structure revealed that the accommodation of gabazine into the “aromatic box” in the orthosteric site lowered the binding energy. This information may help in designing GABAR-targeting insecticides with novel modes of action.

Species identification of bacterial communities in the small brown planthopper, Laodelphax striatellus (Hemiptera: Delphacidae)

AbstractMicrobes are prevalent and abundant in diverse insects. Many microbes are known to influence host fitness. The small brown planthoppers Laodelphax striatellus Fallen is a notorious plant sap‐feeding pest causing heavy loss to rice yield. Some L. striatellus‐associated microbes have been surveyed partially. However, their microbial communities at the species level were poorly identified. In this study, we investigated the bacterial community from 7 populations of L. striatellus using the restriction fragment length polymorphism (RFLP)‐PCR of the 16S rRNA gene. The identified bacteria were assigned into 8 species, the top three of which (Wolbachia sp., Pseudomonas poae and Asaia sp.) accounted for 96% of amplified bacterial sequences. The Wolbachia is of supergroup B and the most abundant in all wild populations. In addition, P. poae was reported in L. striatellus and showed mild pathogenicity. Altogether, our results provide detailed information on the bacterial community in L. striatellus. More research is required to explore the effects of symbiotic bacteria on the fitness of small brown planthoppers.

MAPKs trigger antiviral immunity by directly phosphorylating a rhabdovirus nucleoprotein in plants and insect vectors.

Signaling by the evolutionarily conserved mitogen-activated protein kinase or extracellular signal-regulated kinase (MAPK/ERK) plays critical roles in converting extracellular stimuli into immune responses. However, whether MAPK/ERK signaling induces virus immunity by directly phosphorylating viral effectors remains largely unknown. Barley yellow striate mosaic virus (BYSMV) is an economically important plant cytorhabdovirus that is transmitted by the small brown planthopper (SBPH, Laodelphax striatellus) in a propagative manner. Here, we found that the barley (Hordeum vulgare) MAPK MPK3 (HvMPK3) and the planthopper ERK (LsERK) proteins interact with the BYSMV nucleoprotein (N) and directly phosphorylate N protein primarily on serine 290. The overexpression of HvMPK3 inhibited BYSMV infection, whereas barley plants treated with the MAPK pathway inhibitor U0126 displayed greater susceptibility to BYSMV. Moreover, knockdown of LsERK promoted virus infection in SBPHs. A phosphomimetic mutant of the N Ser290 (S290D) completely abolished virus infection because of impaired self-interaction of BYSMV N and formation of unstable N-RNA complexes. Altogether, our results demonstrate that the conserved MAPK and ERK directly phosphorylate the viral nucleoprotein to trigger immunity against cross-kingdom infection of BYSMV in host plants and its insect vectors.

Silencing suppressors of rice black-streaked dwarf virus and rice stripe virus hijack the 26S proteasome of Laodelphax striatellus to facilitate virus accumulation and transmission.

Rice black-streaked dwarf virus (RBSDV) is transmitted by small brown planthopper (Laodelphax striatellus [L. striatellus]) and causes devastating disease in rice. P9-1 has silencing suppression activity and is the key protein for viroplasm formation in RBSDV-infected plants and insects; however, its exact function is poorly understood. In this study, the P9-1 of RBSDV interacted with L. striatellus 26S proteasome subunit RPN8. RBSDV accumulation in L. striatellus increased after the 26S proteasome was disrupted by silencing the RPN8 expression. This finding indicated that L. striatellus 26S proteasome played a defense role against RBSDV infection by regulating RBSDV accumulation. Further investigations revealed that P9-1 could competitively bind to RPN8 with RPN7, thereby disrupting the assembly of 26S proteasome in L. striatellus and promoting the infection of RBSDV in insect vectors, and further affecting the transmission of the virus to rice by insect vectors. Similar to P9-1, rice stripe virus (RSV) NS2, a weak silencing suppressor, regulated virus accumulation and transmission by hijacking RPN8 to interfere with the function of 26S proteasome in L. striatellus. These results suggest that viruses promote their own infection via interfering with ubiquitination pathway of insect vectors, and this mechanism might be of universal importance. These findings provide a new insight into the mechanism of virus transmission in insect vectors. © 2022 Society of Chemical Industry.

Genetic evidence of transoceanic migration of the small brown planthopper between China and Japan.

The small brown planthopper, Laodelphax striatellus (Fallén), is an important pest of rice. It is suspected of migrating over the sea from China to Japan. However, where in China it comes from and how it affects Japanese populations remain unclear. Here, we studied the genetic structure of 15 L. striatellus populations sampled from Japan and China using single nucleotide polymorphisms generated by the double digest restriction site-associated DNA sequencing technique. We found weak genetic differentiation between the Chinese and Japanese populations. Our data revealed migration signals of L. striatellus from China to southern and northern Japan. However, the source regions of the immigrants remain unclear due to the low genetic differentiation between populations. Our results also pointed to the possibility of backward gene flow from Japanese to Chinese populations. We suspect that the south-eastern wind associated with the East Asian summer monsoon may facilitate the reverse migration of L. striatellus from Japan to China. Interestingly, we found that the X chromosome displayed relatively higher genetic differentiation among populations and suffered more intensive selection pressure than autosomes. We provide genetic evidence of transoceanic migration of L. striatellus from China to Japan and found that the X chromosome can aid the deciphering of the migration trajectories of species with low genetic differentiation. These findings have implications for forecasting the outbreak of this pest and also provide insights into how to improve the tracking of the migration routes of small insects via population genomics. © 2022 Society of Chemical Industry.

Complete sequence and genetic characterization of a novel insect-specific reovirus discovered from Laodelphax striatellus

The small brown planthopper, Laodelphax striatellus (Hemiptera: Delphacidae), is an efficient vector of several economically important plant viruses. In this study, a novel reovirus-like virus was identified in L. striatellus, named Laodelphax striatellus reovirus (LSRV). The complete genome of LSRV was 28,207 nt, comprising of ten segments encoded 11 deduced proteins. All genome segments were conserved with AGUAA at the 5′-terminal and GUUGUC at 3′-terminal and segment-specific inverted terminal repeats. In addition, genomic characteristics and phylogenetic analysis suggested that LSRV was a new member of genus Fijivirus. Importantly, LSRV was widely distributed in various tissues and highest expressed in adult heads. However, LSRV was unable to horizontal replication in rice plants. Moreover, typical profiles of LSRV-derived small interfering RNAs indicated host antiviral RNA interference pathway was involved in LSRV infection. In conclusion, LSRV may be considered as a new species of the genus Fijivirus in the order Reovirales.

Identification of putative binding interface of PI(3,5)P2 lipid on rice black-streaked dwarf virus (RBSDV) P10 protein

Rice black-streaked dwarf virus (RBSDV) is an important reovirus that infects both plants and its transmission vector small brown planthopper, causing severe crop loss. High affinity binding between RBSDV P10 and PI(3,5)P2 lipid layer was measured using biolayer interferometry (BLI). Subcellular co-localization of PI(3,5)P2 and RBSDV P10 was observed on membranous structures in insect cells with stochastic optical reconstruction microscopy (STORM) imaging. Putative interacting sites of PI(3,5)P2 lipid on a computational predicted RBSDV P10 structure were mapped to its “C-domain” (250–470 aa), using HDXMS data. The BLI and STORM results showed binding and co-localization of RBSDV P10, and PI(3,5)P2 on vesicle-like membranous structures were corroborated with the prediction of the binding interface. Understanding the lipid binding sites on viral proteins will lead to developing strategies to block viral-lipid interaction and disrupt viral pathogenesis in insect vectors and to block virus transmission and achieve disease control of crops in the field.

Effects of sublethal concentrations of cyantraniliprole on the biology and metabolic enzyme activities of Laodelphax striatellus (Fallén)

Cyantraniliprole has been widely used in China for controlling many pests, including the small brown planthopper (SBPH) Laodelphax striatellus (Fallén), which is a major pest of rice. Sublethal effects of cyantraniliprole on SBPH have not yet been examined. In this study, 3rd instar nymphs of SBPH were exposed to the LC10, LC20, and LC30 (3.17, 6.07, and 9.70 mg/L) of cyantraniliprole, which led to reductions in survival rate and hatchability of the F0 generation. Compared with the control, sublethal concentrations of cyantraniliprole significantly prolonged the development time of the 4th and 5th instar nymphs of the F1 generation. In the LC10, LC20, and LC30 treatment groups, the nymphal duration was prolonged by 1.98, 0.99, and 2.54 d, respectively. In addition, the sublethal concentrations of cyantraniliprole shortened the adult preoviposition period. The activities of cytochrome P450 monooxygenases and carboxylesterase in SBPH were promoted after treatment with sublethal concentrations of cyantraniliprole. The increase in insecticide resistance may be due to the increase in the activity of detoxification enzymes. Therefore, this research can provide a theoretical reference for the treatment of resistant SBPH.

Genome-wide SNPs reveal the fine-scale population structure of Laodelphax striatellus in China using double-digest restriction site-associated DNA sequencing

The small brown planthopper (SBPH), Laodelphax striatellus (Fallén) is one of the most destructive rice pests and has caused serious economic losses in China. To clarify the genetic differentiation and population genetic structure of this insect pest, we investigated the genomic polymorphisms, genetic differentiation, and phylogeography of 31 SBPH populations from 28 sampling sites from three climatic zones of China using double-digest restriction site-associated DNA sequencing (ddRADseq). In total, 2,813,221,369 high-quality paired-end reads from 306 individuals and 1925 single nucleotide polymorphisms (SNPs) were obtained. Low levels of genetic diversity and significant genetic differentiation were observed among the SBPH populations, and three genetic clusters were detected in China. Neutrality tests and bottleneck analysis provided strong evidence for recent rapid expansion with a severe bottleneck in most populations. Our work provides new insights into the genetics of the SBPH and will contribute to the development of effective management strategies for this pest.

Flotillin 2 Facilitates the Infection of a Plant Virus in the Gut of Insect Vector.

ABSTRACTMost plant viruses require insect vectors for transmission. One of the key steps for the transmission of persistent-circulative plant viruses is overcoming the gut barrier to enter epithelial cells. To date, little has been known about viral cofactors in gut epithelial cells of insect vectors. Here, we identified flotillin 2 as a plasma membrane protein that facilitates the infection of rice stripe virus (RSV) in its vector, the small brown planthopper. Flotillin 2 displayed a prominent plasma membrane location in midgut epithelial cells. The nucleocapsid protein of RSV and flotillin 2 colocalized on gut microvilli, and a nanomolar affinity existed between the two proteins. Knockout of flotillin 2 impeded the entry of virions into epithelial cells, resulting in a 57% reduction of RSV levels in planthoppers. The knockout of flotillin 2 decreased disease incidence in rice plants fed by viruliferous planthoppers from 40% to 11.7%. Furthermore, flotillin 2 mediated the infection of southern rice black-streaked dwarf virus in its vector, the white-backed planthopper. This work implies the potential of flotillin 2 as a target for controlling the transmission of rice stripe disease.IMPORTANCE Plant viral diseases are a major threat to world agriculture. The transmission of 80% of plant viruses requires vector insects, and 54% of vector-borne plant viruses are persistent-circulative viruses, which must overcome the barriers of gut cells with the help of proteins on the cell surface. Here, we identified flotillin 2 as a membrane protein that mediates the cell entry of rice stripe virus in its vector insect, small brown planthopper. Flotillin 2 displays a prominent cellular membrane location in midgut cells and can specifically bind to virions. The loss of flotillin 2 impedes the entry of virions into the midgut cells of vector insects and substantially suppresses viral transmission to rice. Therefore, flotillin 2 may be a promising target gene for manipulation in vector insects to control the transmission of rice stripe disease and perhaps that of other rice virus diseases in the future.

Planthopper-Secreted Salivary Calmodulin Acts as an Effector for Defense Responses in Rice

The brown planthopper (Nilaparvata lugens, BPH) and small brown planthopper (Laodelphax striatellus, SBPH) are major pests of rice (Oryza sativa) in Asia. These piercing-sucking insects secrete saliva into the host during feeding. Nevertheless, it is largely unknown how planthoppers use salivary effectors to enable continuous feeding on rice. Here, we screened their salivary proteomes and selected eight salivary proteins conserved between SBPH and BPH as candidate effectors. Silencing calmodulin (CaM) impeded BPH and SBPH from penetrating the phloem. Hence, their food intake, survival, and fecundity on rice plants were reduced. By contrast, CaM silencing had a small effect on the survival rate of BPH and SBPH raised on artificial diet. The CaM amino acid sequences were the same for both BPH and SBPH. CaM was highly expressed in their salivary glands and secreted into the rice plants during feeding. Bacterially expressed recombinant CaM protein exhibited calcium-binding activity. In planta expression disclosed that CaM was localized to the plant cytoplasms and nuclei and suppressed plant defenses such as hydrogen peroxide (H2O2) accumulation and callose deposition. CaM-silenced BPH and SBPH nymphs elicited relatively high levels of H2O2 and callose accumulation in rice plants. The foregoing results reveal that CaM is an effector as it enables the planthopper to reach the phloem by suppressing callose deposition and H2O2 accumulation in rice.

Developing reverse genetics systems of northern cereal mosaic virus to reveal superinfection exclusion of two cytorhabdoviruses in barley plants.

Recently, reverse genetics systems of plant negative‐stranded RNA (NSR) viruses have been developed to study virus–host interactions. Nonetheless, genetic rescue of plant NSR viruses in both insect vectors and monocot plants is very limited. Northern cereal mosaic virus (NCMV), a plant cytorhabdovirus, causes severe diseases in cereal plants through transmission by the small brown planthopper (SBPH, Laodelphax striatellus) in a propagative manner. In this study, we first developed a minireplicon system of NCMV in Nicotiana benthamiana plants, and then recovered a recombinant NCMV virus (rNCMV‐RFP), with a red fluorescent protein (RFP) insertion, in SBPHs and barley plants. We further used rNCMV‐RFP and green fluorescent protein (GFP)‐tagged barley yellow striate mosaic virus (rBYSMV‐GFP), a closely related cytorhabdovirus, to study superinfection exclusion, a widely observed phenomenon in dicot plants rarely studied in monocot plants. Interestingly, cellular superinfection exclusion of rBYSMV‐GFP and rNCMV‐RFP was observed in barley leaves. Our results demonstrate that two insect‐transmitted cytorhabdoviruses are enemies rather than friends at the cellular level during coinfections in plants.

Heat shock cognate protein 70 is required for rice stripe tenuivirus accumulation and transmission in small brown planthopper.

Rice stripe tenuivirus (RSV) is mainly transmitted by the insect vector small brown planthopper (SBPH, Laodelphax striatellus) in a persistent-propagative manner. Virus transmission is dependent on the interplay between viral proteins and vector factors. Pc2, a nonstructural protein of RSV, plays an important role in virus transmission. However, the vector proteins that interact with Pc2 are unknown. In this study, we identified three SBPH proteins that interact with the N-terminal 381 amino acids of Pc2 (Pc2N) by using a yeast two-hybrid system (Y2H). The interaction of Pc2N with heat shock protein cognate 70 (HSC70) was studied further. HSC70 was verified to interact with RSV Pc2N by biomolecular fluorescence complementation and co-immunoprecipitation assays. HSC70 colocalized with RSV Pc2N in both Sf9 cells and the hemocytes of SBPHs. Inhibition of HSC70 expression via RNA interference reduced virus levels in hemolymph and salivary glands of SBPHs and resulted in decreased virus transmission efficiency. These data provide evidence that a vector protein, HSC70, is employed by RSV to facilitate virus accumulation in the hemolymph and thereby promote virus transmission. These findings are important for a better understanding of the interactions between plant viruses and insect vectors.

Decoyinine Induced Resistance in Rice against Small Brown Planthopper Laodelphax striatellus.

Simple SummarySmall brown planthopper (SBPH, Laodelphax striatellus) is a serious rice sap-sucking insect pest in East Asia, especially in China. Furthermore, it is also a potential vector of rice viral diseases, such as rice stripe virus and rice black streaked dwarf virus, which cause significant yield losses. Here, a novel antimicrobial pesticide, decoyinine was applied as a seed treatment in rice in order to study life table parameters of SBPH and biochemical and physiological indices (having a role in induced systemic resistance in plants) of rice crop in response to SBPH feeding. Decoyinine significantly reduced fecundity in SBPH and also altered chemical and physiological indices of rice in response to SBPH. We conclude that the use of decoyinine in rice will contribute to integrated pest management (IPM) and may potentially provide a new idea for green technology. Induced resistance against SBPH via microbial pesticides is considered as an eco-friendly and promising management approach. In this study, the induced resistance against SBPH in rice seedling by a new potential microbial pesticide, decoyinine (DCY), a secondary metabolite produced by Streptomyces hygroscopicus, was evaluated to investigate the effects of DCY on SBPH’s biological and population parameters along with defense-related physiological and biochemical indices in rice against SBPH feeding. We found that DCY has potential to improve rice resistance and significantly reduced the fecundity of SBPH. Laboratory results revealed that DCY treated rice significantly changed SBPH’s fecundity and population life table parameters. The concentrations of hydrogen peroxide (H2O2), soluble sugars and malondialdehyde (MDA) were significantly lower in DCY treated rice plants against SBPH infestation at 24, 48 and 96 hours post infestation (hpi), respectively. The concentrations of antioxidant enzymes, catalase (CAT) was significantly higher at 72 hpi, while super oxidase dismutase (SOD) and peroxidase (POD) concentrations were recorded higher at 96 hpi. The concentrations of synthases enzymes, phenyl alanine ammonia-lyase (PAL) was higher at 48 hpi, whereas polyphenol oxidase (PPO) concentration was maximum at 72 hpi against SBPH infestation. The results imply that DCY has unique properties to enhance rice resistance against SBPH by stimulating plant defensive responses. Microbial pesticides may be developed as an alternative to chemical pest control.

A cytorhabdovirus-based expression vector in Nilaparvata lugens, Laodelphax striatellus, and Sogatella furcifera

The brown planthopper (BPH, Nilaparvata lugens), the small brown planthopper (SBPH, Laodelphax striatellus), and the white-backed planthopper (WBPH, Sogatella furcifera) are problematic insect pests and cause severe yield losses through phloem sap-sucking and virus transmission. Barley yellow striate mosaic virus (BYSMV), a plant cytorhabdovirus, has been developed as versatile expression platforms in SBPHs and cereal plants. However, bio-safe overexpression vectors based on recombinant BYSMV (rBYSMV) remain to be developed and applied to the three kinds of planthoppers. Here, we found that rBYSMV was able to infect SBPHs, BPHs and WBPHs through microinjection with crude extracts from rBYSMV-infected barley leaves. To ensure bio-safety of the rBYSMV vectors, we generated an rBYSMV mutant by deleting the accessory protein P3, a putative viral movement protein. As expected, the resulting mutant abolished viral systemic infection in barley plants but had no effects on BYSMV infectivity in insect vectors. Subsequently, we used the modified rBYSMV vector to overexpress iron transport peptide (ITP) in the three kinds of planthoppers and revealed the potential functions of ITP. Overall, our results provide bio-safe overexpression platforms to facilitate functional genomics studies of planthoppers.

Risk Odors Deriving from Predator Abdominal Gland Secretions Mediate Non-Consumptive Effects on Prey.

Prey can detect the presence of predators by predator-released cues and then flexibly alter their phenotypical traits to mitigate the risk, thus non-consumptive effects emerge. Non-consumptive effects have been widely studied in many ecosystems, however, the mechanisms underlying these effects are poorly understood, leaving questions as to the nature of the risk cues and how prey detect the predator. Here, we used a Y-tube olfactometer to examine whether small brown planthoppers, Laodelphax striatellus (Fallén), could detect the presence of rove beetles (Paederus fuscipes Curtis) via odor from rove beetle abdominal gland secretion. We further identified the chemicals of abdominal gland secretion by gas chromatography-mass spectrometry. Chemicals identified were exposed to a planthopper to test their effects on planthopper behavior. Female or male planthoppers could distinguish the predation risk odors of rove beetle or rove beetle abdominal gland secretion from odor without predation risks. Through gas chromatography-mass spectrometry, sixteen of the most abundant chemicals were found in female and male abdominal gland secretion. Five of them (n-undecane, n-pentadecane, n-hexadecane, n-eicosane, and n-heneicosane) individually or collectively reduced the activity level of planthoppers. These findings enhance our understanding of the role of abdominal gland secretion in mediating non-consumptive predator effects, with significant implications for pest management, and the evolution of chemical signals.

Alternative Splicing Landscape of Small Brown Planthopper and Different Response of JNK2 Isoforms to Rice Stripe Virus Infection.

Alternative splicing (AS) is a frequent posttranscriptional regulatory event occurring in response to various endogenous and exogenous stimuli in most eukaryotic organisms. However, little is known about the effects of insect-transmitted viruses on AS events in insect vectors. The present study used third-generation sequencing technology and RNA sequencing (RNA-Seq) to evaluate the AS response in the small brown planthopper Laodelphax striatellus to rice stripe virus (RSV). The full-length transcriptome of L. striatellus was obtained using single-molecule real-time sequencing technology (SMRT). Posttranscriptional regulatory events, including AS, alternative polyadenylation, and fusion transcripts, were analyzed. A total of 28,175 nonredundant transcript isoforms included 24,950 transcripts assigned to 8,500 annotated genes of L. striatellus, and 5,000 of these genes (58.8%) had AS events. RNA-Seq of the gut samples of insects infected by RSV for 8 d identified 3,458 differentially expressed transcripts (DETs); 2,185 of these DETs were transcribed from 1,568 genes that had AS events, indicating that 31.4% of alternatively spliced genes responded to RSV infection of the gut. One of the c-Jun N-terminal kinase (JNK) genes, JNK2, experienced exon skipping, resulting in three transcript isoforms. These three isoforms differentially responded to RSV infection during development and in various organs. Injection of double-stranded RNAs targeting all or two isoforms indicated that three or at least two JNK2 isoforms facilitated RSV accumulation in planthoppers. These results implied that AS events could participate in the regulation of complex relationships between viruses and insect vectors. IMPORTANCE Alternative splicing (AS) is a regulatory mechanism that occurs after gene transcription. AS events can enrich protein diversity to promote the reactions of the organisms to various endogenous and exogenous stimulations. It is not known how insect vectors exploit AS events to cope with transmitted viruses. The present study used third-generation sequencing technology to obtain the profile of AS events in the small brown planthopper Laodelphax striatellus, which is an efficient vector for rice stripe virus (RSV). The results indicated that 31.4% of alternatively spliced genes responded to RSV infection in the gut of planthoppers. One of the c-Jun N-terminal kinase (JNK) genes, JNK2, produced three transcript isoforms by AS. These three isoforms showed different responses to RSV infection, and at least two isoforms facilitated viral accumulation in planthoppers. These results implied that AS events could participate in the regulation of complex relationships between viruses and insect vectors.

Application of predator-associated cues to control small brown planthoppers: non-consumptive effects of predators suppress the pest population

Application of predator-associated cues to control small brown planthoppers: non-consumptive effects of predators suppress the pest population