How does saliva function in planthopper-host interactions?

Proteomic Analysis of Salivary Secretions from the Tea Green Leafhopper, Empoasca flavescens Fabrecius

Saliva plays a crucial role in shaping the compatibility of piercing-sucking insects with their host plants. Understanding the complex composition of leafhopper saliva is important for developing effective and eco-friendly control strategies for the tea green leafhopper, Empoasca flavescens Fabrecius, a major piercing-sucking pest in Chinese tea plantations. This study explored the saliva proteins of tea green leafhopper adults using a custom collection device, consisting of two layers of Parafilm stretched over a sucrose diet. A total of 152 proteins were identified using liquid chromatography-tandem mass spectrometry (LC-MS/MS) following the filter-aided sample preparation (FASP). These proteins were categorized into six groups based on their functions, including enzymes, transport proteins, regulatory proteins, cell structure proteins, other proteins, and unknown proteins. Bioinformatics analyses predicted 16 secreted proteins, which were successfully cloned and transcriptionally analyzed across various tissues and developmental stages. Genes encoding putative salivary secretory proteins, including Efmucin1, EfOBP1, EfOBP2, EfOBP3, Efmucin2, low-density lipoprotein receptor-related protein (EfLRP), EFVg1, and EFVg2, exhibited high expressions in salivary gland (SG) tissues and feeding-associated expressions at different developmental stages. These findings shed light on the potential elicitors or effectors mediating the leafhopper feeding and defense responses in tea plants, providing insights into the coevolution of tea plants and leafhoppers. The study's conclusions open avenues for the development of innovative leafhopper control technologies that reduce the reliance on pesticides in the tea industry.

Cross-kingdom RNA interference mediated by insect salivary microRNAs may suppress plant immunity

Communication between insects and plants relies on the exchange of bioactive molecules that traverse the species interface. Although proteinic effectors have been extensively studied, our knowledge of other molecules involved in this process remains limited. In this study, we investigate the role of salivary microRNAs (miRNAs) from the rice planthopper Nilaparvata lugens in suppressing plant immunity. A total of three miRNAs were confirmed to be secreted into host plants during insect feeding. Notably, the sequence-conserved miR-7-5P is specifically expressed in the salivary glands of N. lugens and is secreted into saliva, distinguishing it significantly from homologues found in other insects. Silencing miR-7-5P negatively affects N. lugens feeding on rice plants, but not on artificial diets. The impaired feeding performance of miR-7-5P-silenced insects can be rescued by transgenic plants overexpressing miR-7-5P. Through target prediction and experimental testing, we demonstrate that miR-7-5P targets multiple plant genes, including the immune-associated bZIP transcription factor 43 (OsbZIP43). Infestation of rice plants by miR-7-5P-silenced insects leads to the increased expression of OsbZIP43, while the presence of miR-7-5P counteracts this upregulation effect. Furthermore, overexpressing OsbZIP43 confers plant resistance against insects which can be subverted by miR-7-5P. Our findings suggest a mechanism by which herbivorous insects have evolved salivary miRNAs to suppress plant immunity, expanding our understanding of cross-kingdom RNA interference between interacting organisms.

A pipeline contributes to efficient identification of salivary proteins in short-headed planthopper, Epeurysa nawaii

Saliva, an oral secretion primarily originating from salivary glands (SGs), exert critical roles in the ongoing evolutionary interaction between insects and plants. However, identifying insect salivary components poses challenges due to the tiny size of insects, low secretion amounts, and the propensity for degradation after secretion. In this study, we developed a transcriptome-based approach to comprehensively analyze the salivary proteins of the short-headed planthopper, Epeurysa nawaii, a species with unique feeding habits on bamboo. A total of 165 salivary proteins were identified, with 114 secretory genes highly and specifically expressed in SGs. Consistent with most phloem-feeding insects, digestive enzymes, calcium-binding proteins, oxidoreductases, and a few previously reported salivary effectors were ubiquitously distributed in E. nawaii saliva. However, we also identified a substantial portion of salivary proteins exhibiting taxonomy specificity, including 60 E. nawaii-specific and 62 Delphacidae-specific proteins. These taxonomy-restricted proteins potentially play a role in insect adaptation to specific host plants. Our study provides an efficient pipeline for salivary protein identification and serves as a valuable resource for the functional characterization of effectors.

Salivary proteins potentially derived from horizontal gene transfer are critical for salivary sheath formation and other feeding processes

Herbivorous insects employ an array of salivary proteins to aid feeding. However, the mechanisms behind the recruitment and evolution of these genes to mediate plant-insect interactions remain poorly understood. Here, we report a potential horizontal gene transfer (HGT) event from bacteria to an ancestral bug of Eutrichophora. The acquired genes subsequently underwent duplications and evolved through co-option. We annotated them as horizontal-transferred, Eutrichophora-specific salivary protein (HESPs) according to their origin and function. In Riptortus pedestris (Coreoidea), all nine HESPs are secreted into plants during feeding. The RpHESP4 to RpHESP8 are recently duplicated and found to be indispensable for salivary sheath formation. Silencing of RpHESP4-8 increases the difficulty of R. pedestris in probing the soybean, and the treated insects display a decreased survivability. Although silencing the other RpHESPs does not affect the salivary sheath formation, negative effects are also observed. In Pyrrhocoris apterus (Pyrrhocoroidea), five out of six PaHESPs are secretory salivary proteins, with PaHESP3 being critical for insect survival. The PaHESP5, while important for insects, no longer functions as a salivary protein. Our results provide insight into the potential origin of insect saliva and shed light on the evolution of salivary proteins.

Comparative transcriptomic analysis of salivary glands between the zoophytophagous Cyrtorhinus lividipennis and the phytozoophagous Apolygus lucorum

BACKGROUND

Saliva plays a crucial role in shaping the feeding behavior of insects, involving processes such as food digestion and the regulation of interactions between insects and their hosts. Cyrtorhinus lividipennis serves as a predominant natural enemy of rice pests, while Apolygus lucorum, exhibiting phytozoophagous feeding behavior, is a destructive agricultural pest. In this study, a comparative transcriptome analysis, incorporating the published genomes of C.lividipennis and A.lucorum, was conducted to reveal the role of salivary secretion in host adaptation.

RESULTS

In contrast to A.lucorum, C.lividipennis is a zoophytophagous insect. A de novo genome analysis of C.lividipennis yielded 19,706 unigenes, including 16,217 annotated ones. On the other hand, A.lucorum had altogether 20,111 annotated genes, as obtained from the published official gene set (20,353 unigenes). Functional analysis of the top 1,000 salivary gland (SG)-abundant genes in both insects revealed that the SG was a dynamically active tissue engaged in protein synthesis and secretion. Predictions of other tissues and signal peptides were compared. As a result, 94 and 157 salivary proteins were identified in C.lividipennis and A.lucorum, respectively, and were categorized into 68 and 81 orthogroups. Among them, 26 orthogroups were shared, potentially playing common roles in digestion and detoxification, including several venom serine proteases. Furthermore, 42 and 55 orthogroups were exclusive in C.lividipennis and A.lucorum, respectively, which were exemplified by a hyaluronidase in C.lividipennis that was associated with predation, while polygalacturonases in A.lucorum were involved in mesophyll-feeding patterns.

CONCLUSIONS

Findings in this study provide a comprehensive insight into saliva secretions in C.lividipennis and A.lucorum via a transcriptome approach, reflecting the intricate connections between saliva secretions and feeding behaviors. It is found that conserved salivary secretions are involved in shaping the overlapping feeding patterns, while a plethora of unique salivary secretions may drive the evolution of specific feeding behaviors crucial for their survival. These results enhance our understanding of the feeding mechanisms in different insects from the perspective of saliva and contribute to future environmentally friendly pest control by utilizing predatory insects.

Mealybug salivary microbes inhibit induced plant defenses

BACKGROUND

Phenacoccus solenopsis is a polyphagous invasive mealybug that caused serious damage to crops worldwide. Phloem-sucking hemipterans are known to carry symbiotic microbes in their saliva. However, the role of salivary bacteria of P. solenopsis in modulating plant defenses remains limited. Exploring the impact of salivary bacteria on plant defense responses will contribute to the development of new targets for efficient control of invasive mealybugs.

RESULTS

Salivary bacteria of the invasive mealybug P. solenopsis can suppress herbivore-induced plant defenses and thus enhance mealybug fitness. Mealybugs treated with an antibiotic showed decreased weight gain, fecundity and survival. Untreated mealybugs suppressed jasmonic acid (JA)-regulated defenses but activated salicylic acid (SA)-regulated defenses in cotton plants. In contrast, antibiotic-treated mealybugs triggered JA-responsive gene expression and JA accumulation, and showed shortened phloem ingestion. Reinoculating antibiotic-treated mealybugs with Enterobacteriaceae or Stenotrophomonas cultivated from mealybug saliva promoted phloem ingestion and fecundity, and restored the ability of mealybugs to suppress plant defenses. Fluorescence in situ hybridization visualization revealed that Enterobacteriaceae and Stenotrophomonas colonize salivary glands and are secreted into the mesophyll cells and phloem vessels. Exogenous application of the bacterial isolates to plant leaves inhibited JA-responsive gene expression and activated SA-responsive gene expression.

CONCLUSION

Our findings imply that symbiotic bacteria in the saliva of the mealybug play an important role in manipulating herbivore-induced plant defenses, enabling this important pest to evade induced plant defenses and promoting its performance and destructive effects on crops. © 2023 Society of Chemical Industry.

Saliva-Mediated Contrasting Effects of Two Citrus Aphid Species on Asian Citrus Psyllid Feeding Behavior and Plant Jasmonic Acid Pathway

While herbivorous insect saliva plays a crucial role in the interaction between plants and insects, its role in the inter-specific interactions between herbivorous insects has received little attention. Pre-infestation of citrus plants with Aphis spiraecola Patch and Aphis (Toxoptera) citricidus (Kirkaldy) exhibited positive and negative effects on the performance (feeding and reproduction) of Diaphorina citri Kuwayama. We explored the role of saliva in this plant-mediated interaction by infiltrating fresh and boiled aphid saliva into plants and detecting D. citri feeding behavior and citrus plant defense response. Leaf infiltration of A. spiraecola saliva disrupted the subsequent feeding of D. citri, indicated by prolonged extracellular stylet pathway duration and decreased phloem sap ingestion duration. By contrast, infiltration of A. citricidus saliva decreased the duration of the extracellular stylet pathway and phloem sap ingestion of D. citri. Furthermore, gene expression analysis showed that several salicylic acid (SA)- and jasmonic acid (JA)-pathway-related genes were activated by A. spiraecola saliva infiltration. However, two SA-pathway-related genes were activated and three JA-pathway-related genes were suppressed following A. citricidus saliva infiltration. Treatment with boiled saliva did not similarly impact D. citri feeding behavior or plant defense response. This study suggests that salivary components (those that can be inactivated by heating) from two citrus aphid species differently affect plant defenses and that they were responsible for the contrasting plant-mediated effects of two citrus aphids on the feeding behavior of D. citri. This study indicates a novel three-way citrus aphid-plant-citrus psyllid interaction.

Cyclophilin effector Al106 of mirid bug Apolygus lucorum inhibits plant immunity and promotes insect feeding by targeting PUB33

Apolygus lucorum (Meyer-Dur; Heteroptera: Miridae) is a major agricultural pest infesting crops, vegetables, and fruit trees. During feeding, A. lucorum secretes a plethora of effectors into its hosts to promote infestation. However, the molecular mechanisms of these effectors manipulating plant immunity are largely unknown. Here, we investigated the molecular mechanism underlying the effector Al106 manipulation of plant-insect interaction by RNA interference, electrical penetration graph, insect and pathogen bioassays, protein-protein interaction studies, and protein ubiquitination experiment. Expression of Al106 in Nicotiana benthamiana inhibits pathogen-associated molecular pattern-induced cell death and reactive oxygen species burst, and promotes insect feeding and plant pathogen infection. In addition, peptidyl-prolyl cis-trans isomerase (PPIase) activity of Al106 is required for its function to inhibit PTI.Al106 interacts with a plant U-box (PUB) protein, PUB33, from N. benthamiana and Arabidopsis thaliana. We also demonstrated that PUB33 is a positive regulator of plant immunity. Furthermore, an in vivo assay revealed that Al106 inhibits ubiquitination of NbPUB33 depending on PPIase activity. Our findings revealed that a novel cyclophilin effector may interact with plant PUB33 to suppress plant immunity and facilitate insect feeding in a PPIase activity-dependent manner.

Planthopper salivary sheath protein LsSP1 contributes to manipulation of rice plant defenses

Salivary elicitors secreted by herbivorous insects can be perceived by host plants to trigger plant immunity. However, how insects secrete other salivary components to subsequently attenuate the elicitor-induced plant immunity remains poorly understood. Here, we study the small brown planthopper, Laodelphax striatellus salivary sheath protein LsSP1. Using Y2H, BiFC and LUC assays, we show that LsSP1 is secreted into host plants and binds to salivary sheath via mucin-like protein (LsMLP). Rice plants pre-infested with dsLsSP1-treated L. striatellus are less attractive to L. striatellus nymphs than those pre-infected with dsGFP-treated controls. Transgenic rice plants with LsSP1 overexpression rescue the insect feeding defects caused by a deficiency of LsSP1 secretion, consistent with the potential role of LsSP1 in manipulating plant defenses. Our results illustrate the importance of salivary sheath proteins in mediating the interactions between plants and herbivorous insects.

Calcium Signaling in Plant-Insect Interactions

In plant-insect interactions, calcium (Ca²⁺) variations are among the earliest events associated with the plant perception of biotic stress. Upon herbivory, Ca²⁺ waves travel long distances to transmit and convert the local signal to a systemic defense program. Reactive oxygen species (ROS), Ca²⁺ and electrical signaling are interlinked to form a network supporting rapid signal transmission, whereas the Ca²⁺ message is decoded and relayed by Ca²⁺-binding proteins (including calmodulin, Ca²⁺-dependent protein kinases, annexins and calcineurin B-like proteins). Monitoring the generation of Ca²⁺ signals at the whole plant or cell level and their long-distance propagation during biotic interactions requires innovative imaging techniques based on sensitive sensors and using genetically encoded indicators. This review summarizes the recent advances in Ca²⁺ signaling upon herbivory and reviews the most recent Ca²⁺ imaging techniques and methods.

Laodelphax striatellus saliva mucin enables the formation of stylet sheathes to facilitate its feeding and rice stripe virus transmission

BACKGROUND

Laodelphax striatellus transmits rice stripe virus (RSV) during sap feeding on the rice plant. The insect saliva proteins have direct and indirect roles in mediating RSV transmission; however, the function of most saliva proteins remains unclear.

RESULTS

In this study, we sequenced L. striatellus saliva proteins using shotgun liquid chromatography-electrospray ionization-tandem mass spectrometry. We identified 41 secreted saliva proteins, among which a saliva mucin-like protein, designated LssaMP, was the most abundant. In silico analysis revealed the sequence conservation among planthoppers. We revealed that the LssaMP gene is specifically expressed in the salivary glands and the protein is secreted as a component of gel saliva. Using LssaMP-specific double-stranded RNA (dsRNA) to silence gene expression, we revealed that LssaMP is required for formation of the salivary sheath, an important structure for sap feeding. Disrupting LssaMP expression resulted in inefficient formation of the feeding structure, thereby stopping insects from secreting watery saliva and acquiring sufficient nutrients from the phloem sap. We confirmed that RSV is mainly released via the watery saliva, which passes through the salivary sheathes into the plant phloem. An insufficient feeding structure results in decreased release of watery saliva, as well as the arboviruses.

CONCLUSION

This study clarified the function of an insect saliva protein in mediating insect feeding, as well as arbovirus transmission. © 2022 Society of Chemical Industry.

Heat Shock 70 kDa Protein Cognate 3 of Brown Planthopper Is Required for Survival and Suppresses Immune Response in Plants

The brown planthopper (Nilaparvata lugens) is a monophagous pest of rice (Oryza sativa), which threatens food security around the world. Insect Heat shock proteins 70 kDa (Hsp70s) play a key role in insect growth and development, however, if they also modulate the plant physiological processes is still unclear. In this study, we identified the Heat shock 70 kDa protein cognate 3 (NlHSC70-3) of BPH from compared protein profiles of Nipponbare tissues after BPH infestation via LC/MS. NlHSC70-3 has a predicted signal peptide and displays high transcription levels in the salivary glands, which further supported that it is secreted into plants by BPH during the feeding process. Using RNA interference (RNAi), we showed that NlHSC70-3 is indispensable for the survival of BPH on rice. Most importantly, NlHSC70-3 mediates the plant immune responses including cell death, flg22-induced ROS burst and defense-related gene expression in N. benthamiana. These results demonstrate that NlHSC70-3 may function as an effector manipulating plant physiological processes to facilitate pest survival on rice, which provides a new potential target for future pest control.

Characterization of Salivary Secreted Proteins That Induce Cell Death From Riptortus pedestris (Fabricius) and Their Roles in Insect-Plant Interactions

Riptortus pedestris (Fabricius) is a polyphagous hemipteran crop pest that mainly feeds on the leguminous plants, resulting in shriveled and dimpled seeds. With recent several outbreaks in the Huang-Huai-Hai region of China, as well as in South Korea and Japan, this species has caused enormous economic losses to soybean crops. In the present study, we found that R. pedestris feeding results in local lesions at the infestation sites. To identify the key effectors that induce plant damage during feeding, the salivary glands of R. pedestris were dissected for transcriptome sequencing, and 200 putative secreted proteins were transiently expressed in N. benthamiana. Among them, three intracellular effectors (RP191, RP246, and RP302) and one apoplastic effector (RP309) were identified as necrosis-inducing proteins (NIPs), which also triggered the reactive oxidative burst. Yeast signal sequence trap and qRT-PCR analysis suggested that these proteins might be secreted into plant tissue during R. pedestris infestation. Pathogenicity assays revealed that RP191, 246, and 302 promote Phytophthora capsici infection or induce Spodoptera litura feeding by inhibiting plant immunity. RP302 is localized to the cytoplasm and nuclei, while RP191 and 246 are endoplasmic reticulum (ER) resident proteins. RP309 stimulates the expression of PTI marker genes, and its induced cell death depends on co-receptors NbBAK1 and NbSOBIR1, indicating that it is a HAMP. Bioinformatics analysis demonstrated that four NIPs are recently evolved effectors and only conserved in the Pentatomidae. In this study, saliva-secreted proteins were used as the starting point to preliminarily analyze the harm mechanism of R. pedestris, which might provide a new idea and theoretical basis for this species control.

Arms and ammunitions: effectors at the interface of rice and it's pathogens and pests

The plant immune system has evolved to resist attack by pathogens and pests. However, successful phytopathogens deliver effector proteins into plant cells where they hijack the host cellular machinery to suppress the plant immune responses and promote infection. This manipulation of the host cellular pathways is done by the pathogen using various enzymatic activities, protein- DNA or protein- protein interactions. Rice is one the major economically important crops and its yield is affected by several pathogens and pests. In this review, we summarize the various effectors at the plant- pathogen/ pest interface for the major pathogens and pests of rice, specifically, on the mode of action and target genes of the effector proteins. We then compare this across the major rice pathogens and pests in a bid to understand probable conserved pathways which are under attack from pathogens and pests in rice. This analysis highlights conserved patterns of effector action, as well as unique host pathways targeted by the pathogens and pests.

Identification of salivary proteins in the whitefly Bemisia tabaci by transcriptomic and LC-MS/MS analyses

The whitefly Bemisia tabaci is a notorious agricultural pest of many crops worldwide. Although it is thought that B. tabaci secretes saliva into the host plant to counter plant defenses, knowledge on the whitefly salivary proteome is limited. Here, we characterized the gene/protein repertoires of B. tabaci salivary glands and secreted saliva by transcriptomic and liquid chromatography tandem mass spectroscopy analyses. A total of 698 salivary gland-enriched unigenes and 171 salivary proteins were identified. Comparative analysis between the B. tabaci salivary proteins and those of different arthropod species revealed numerous similarities in proteins associated with binding, hydrolysis, and oxidation-reduction, which demonstrates a degree of conservation across herbivorous saliva. There were 74 proteins only identified in B. tabaci saliva, of which 34 were B. tabaci-specific. In addition, 13 salivary proteins, of which 11 were B. tabaci-specific, were differentially regulated when B. tabaci fed on different hosts. Our results provide a good resource for future functional studies of whitefly salivary effectors, and might be useful in pest management.

Insight into different host range of three planthoppers by transcriptomic and microbiomic analysis

Brown planthopper (BPH), white-backed planthopper (WBPH) and small brown planthopper (SBPH), are the closely related rice pests that perform differentially on wheat plants. Using fecundity as a fitness measure, we found that SBPH well-adapted on wheat plants, followed by WBPH, while BPH had the worst performance. The transcriptomic responses of SBPH and BPH to wheat plants have been compared previously. To understand the different fitness mechanisms of three planthoppers, this study first investigated the transcriptomic responses of WBPH to rice and wheat plants. Genes involved in detoxification, transportation and proteasome were significantly enriched in WBPH in response to different diets. Moreover, comparative analysis demonstrated that most co-regulated genes in BPH and SBPH showed different expression changes; whereas most co-regulated genes in BPH and WBPH exhibited similar expression changes. Subsequently, this study also investigated the influences of host plants on the bacterial community of three planthoppers. The three planthoppers harboured distant diversity of bacterial communities. However, there was no dramatic change in bacterial diversity or relative abundance in planthoppers colonized on different hosts. This study illustrates generic and species-specific changes of three rice planthoppers in response to different plants, which deepen our understanding towards the host fitness for planthopper species.

Extraoral digestion: outsourcing the role of the hemipteran midgut

Extraoral digestion allows for breakdown of dietary components before they reach the midgut for final enzymatic degradation and absorption. In the Hemiptera, this is achieved by the secretion of enzyme-rich fluids from the salivary gland, with the combination of protein and mRNA from these tissues termed the sialome. Separate channels within the hemipteran stylets allow for secretion of saliva and ingestion of predigested material in a non-reflux mechanism. Both feeding mode and diet type influence the composition of the hemipteran sialome, as illustrated by 1) differences in protease abundance between hematophagous and predatory heteropteran sialomes, 2) diet specific aminopeptidase-N genes among aphid biotypes, and 3) adaptation-induced sialome variation in related cicada populations. Despite challenges associated with incomplete genome annotation, -omics analysis of the sialomes of diverse hemipteran species will enhance understanding of both sialome function and the evolution of extraoral digestion within the order.

Comparative analysis of diet-associated responses in two rice planthopper species

Background

Host adaptation is the primary determinant of insect diversification. However, knowledge of different host ranges in closely related species remains scarce. The brown planthopper (Nilaparvata lugens, BPH) and the small brown planthopper (Laodelphax striatellus, SBPH) are the most destructive insect pests within the family Delphacidae. These two species differ in their host range (SBPH can well colonize rice and wheat plants, whereas BPH survives on only rice plants), but the underlying mechanism of this difference remains unknown. High-throughput sequencing provides a powerful approach for analyzing the association between changes in gene expression and the physiological responses of insects. Therefore, gut transcriptomes were performed to elucidate the genes associated with host adaptation in planthoppers. The comparative analysis of planthopper responses to different diets will improve our knowledge of host adaptation regarding herbivorous insects.

Results

In the present study, we analyzed the change in gene expression of SBPHs that were transferred from rice plants to wheat plants over the short term (rSBPH vs tSBPH) or were colonized on wheat plants over the long term (rSBPH vs wSBPH). The results showed that the majority of differentially expressed genes in SBPH showed similar changes in expression for short-term transfer and long-term colonization. Based on a comparative analysis of BPH and SBPH after transfer, the genes associated with sugar transporters and heat-shock proteins showed similar variation. However, most of the genes were differentially regulated between the two species. The detoxification-related genes were upregulated in SBPH after transfer from the rice plants to the wheat plants, but these genes were downregulated in BPH under the same conditions. In contrast, ribosomal-related genes were downregulated in SBPH after transfer, but these genes were upregulated in BPH under the same conditions.

Conclusions

The results of this study provide evidence that host plants played a dominant role in shaping gene expression and that the low fitness of BPH on wheat plants might be determined within 24 h after transfer. This study deepens our understanding of different host ranges for the two planthopper species, which may provide a potential strategy for pest management.

Salivary DNase II from Laodelphax striatellus acts as an effector that suppresses plant defence

Extracellular DNA, released by damaged plant cells, acts as a damage-associated molecular pattern (DAMP). We demonstrated previously that the small brown planthopper (Laodelphax striatellus, SBPH) secreted DNase II when feeding on artificial diets. However, the function of DNase II in insect feeding remained elusive. The influences of DNase II on SBPHs and rice plants were investigated by suppressing expression of DNase II or by application of heterogeneously expressed DNase II. We demonstrated that DNase II is mainly expressed in the salivary gland and is responsible for DNA-degrading activity of saliva. Knocking down the expression of DNase II resulted in decreased performance of SBPH reared on rice plants. The dsDNase II-treated SBPH did not influenced jasmonic acid (JA), salicylic acid (SA), ethylene (ET) pathways, but elicited a higher level of H2 O2 and callose accumulation. Application of heterogeneously expressed DNase II in DNase II-deficient saliva slightly reduced the wound-induced defence response. We propose a DNase II-based invading model for SBPH feeding on host plants, and provide a potential target for pest management.