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Simple Summary: We exposed brown planthoppers (BPHs) Nilaparvata lugens to the entomopathogenic fungus Cordyceps javanica PSUC002 and observed morpho-histological changes from 0 to 120 h post-inoculation (pi). At 12 h pi, we observed the first filamentous fungi on the external integument and the first fungal conidia penetrated host planthopper cells at 24 h pi. In contrast, we observed the initial degeneration of BPHs at 6 h pi, especially in the integument and adipose tissue. We also found the degeneration of integument and adipose tissue at 12 h pi, and their completed necrosis became clear at 96 h pi. This study illustrated the process of C. javanica infection in BPHs and demonstrated that fungal agents can be used to control the BPHs in an integrated pest management (IPM) program. The brown planthopper (BPH), Nilaparvata lugens (Stål, 1854), is a pest of rice plants worldwide. Cordyceps javanica is a destructive entomopathogenic fungus known to attack leafhoppers or BPHs specifically. Live adult BPH samples were inoculated with isolated C. javanica PSUC002, and their interaction was morpho-histologically examined from 0 to 120 h post-inoculation (pi). We observed that the mortality of BPH continuously increased until 120 h pi (Day 5). Tissue alterations in the host were examined after infection using morphological and histological methods, including the Grocott Methenamine Silver stain test (GMS). Filamentous fungi were first found on the external integument at 12 h pi, and fungal conidia attached to the integument at 24 h pi. However, the initial degeneration of BPHs was identified by histology at 6 h pi especially in the integument and adipose tissue. We identified the degeneration and loss of integument and adipose tissue of infected BPHs at 12 h pi, and their necrosis was completed at 96 h pi. The enzymatic index of the sampled fungi (chitinase and protease) peaked at 7 days of incubation. This study demonstrated that C. javanica PSUC002 is useful to control the BPHs as an eco-friendly practice and will possibly be applied in agriculture. [ABSTRACT FROM AUTHOR]

The gene encoding 9-cis-epoxycarotenoid dioxygenase 3 (NCED3) functions in abscisic acid (ABA) biosynthesis, plant growth and development, and tolerance to adverse temperatures, drought and saline conditions. In this study, three rice lines were used to explore the function of OsNCED3, these included an OsNCED3-overexpressing line (OsNCED3-OE), a knockdown line (osnced3- RNAi) and wild-type rice (WT). These rice lines were infested with the brown plant hopper (BPH; Nilaparvata lugens) and examined for physiological and biochemical changes, hormone content, and defense gene expression. The results showed that OsNCED3 activated rice defense mechanisms, which led to an increased defense enzyme activity of superoxide dismutase, peroxidase, and polyphenol oxidase. The overexpression of OsNCED3 decreased the number of planthoppers and reduced oviposition and BPH hatching rates. Furthermore, the overexpression of OsNCED3 increased the concentrations of jasmonic acid, jasmonyl-isoleucine and ABA relative to WT rice and the osnced3-RNAi line. These results indicate that OsNCED3 improved the stress tolerance in rice and support a role for both jasmonates and ABA as defense compounds in the rice- BPH interaction. [ABSTRACT FROM AUTHOR]

Green leaf volatiles (GLVs) play pivotal roles in plant anti-herbivore defense. This study investigated whether the rice 13-lipoxygense gene OsRCI-1 is involved in GLV production and plant defense in rice. The overexpression of OsRCI-1 (oeRCI lines) in rice resulted in increased wound-induced levels of two prominent GLVs, cis-3-hexen-1-ol and cis-3-hexenal. In a previous study, we found that the overexpression of OsRCI-1 reduced the colonization by the rice brown planthopper (BPH, Nilaparvata lugens) but increased the attractiveness to the egg parasitoid Anagrus nilaparvatae compared to wild-type (WT) plants. This study found that when cis-3-hexen-1-ol, but not cis-3-hexenal, was added to WT plants, it could change the BPH's colonization preference, i.e., more BPHs preferred to colonize the oeRCI lines. The exogenous application of cis-3-hexen-1-ol or cis-3-hexenal to BPH-infested WT plants could weaken or overturn the preference of A. nilaparvatae for oeRCI lines. However, field experiments revealed that only cis-3-hexenal was attractive to the parasitoid and increased the parasitism rates of BPH eggs. These results indicate that OsRCI-1 is involved in rice GLV production and therefore modulates both direct and indirect defense in rice. [ABSTRACT FROM AUTHOR]

Screening of 50 rice genotypes against brown planthopper infestation was conducted in open field conditions over two consecutive years (Kharif 2018-19 and 2019-20). Based on pest population per hill, rice genotypes IR82475-110-2-2-1-2, Akshyadhan, and MTU-1010 had the least brown planthoppers. TN1, Swarna, MTU 7029, Rajendra Kasturi, Baranideep, and Sahbhagidhan had the highest population and were classified as pest-prone. Rice leaf biochemical characteristics examined in selected genotypes, revealed that the pest population was significantly and positively correlated with total sugar (r = 0.608), crude protein (r = 0.306) and total free amino acid (r = 0.358), but significantly negatively correlated with phenol (r = -0.429), crude silica (r = -0.401), and tannin (r = -0.301). Correlation analysis revealed that susceptible entries contained more total sugar, crude protein, and total free amino acids, whereas resistant genotypes contained significantly more phenol, crude silica, and tannins. This study highlighted the significance of antixenotic properties in rice genotypes against brown planthoppers. [ABSTRACT FROM AUTHOR]

Introduction: The brown planthopper (BPH) poses a significant threat to rice production in Asia. The use of resistant rice varieties has been effective inmanaging this pest. However, the adaptability of BPH to resistant rice varieties has led to the emergence of virulent populations, such as biotype Y BPH. YHY15 rice, which carries the BPH resistance gene Bph15, exhibits notable resistance to biotype 1 BPH but is susceptible to biotype Y BPH. Limited information exists regarding how resistant rice plants defend against BPH populations with varying levels of virulence. Methods: In this study, we integrated miRNA and mRNA expression profiling analyses to study the differential responses of YHY15 rice to both avirulent (biotype 1) and virulent (biotype Y) BPH. Results: YHY15 rice demonstrated a rapid response to biotype Y BPH infestation, with significant transcriptional changes occurring within 6 hours. The biotype Yresponsive genes were notably enriched in photosynthetic processes. Accordingly, biotype Y BPH infestation induced more intense transcriptional responses, affecting miRNA expression, defenserelated metabolic pathways, phytohormone signaling, and multiple transcription factors. Additionally, callose deposition was enhanced in biotype Y BPH-infested rice seedlings. Discussion: These findings provide comprehensive insights into the defense mechanisms of resistant rice plants against virulent BPH, and may potentially guide the development of insect-resistant rice varieties. [ABSTRACT FROM AUTHOR]

Rice is cultivated and consumed worldwide. It belongs to genus 'Oryza' with about 21 wild relatives and eight identified genomes which makes it accessible to the huge pool of genetic resources. The rice crop can be distressed by various biotic and abiotic stressors that affect its productivity. Brown planthoppers (BPH) are major pests of different persistent biotypes in different regions. Several major and minor genes and quantitative trait loci (QTLs) regulate BPH resistance, a composite character. These genes/QTLs employ different resistance mechanisms and may be specific to each biotype. 22 of the 44 BPH genes are found in the wild cousins of rice. Several genes have been discovered, cloned, functionally assessed, and introduced into various lines. Most of the identified genes have not been functionally studied rendering their mechanisms to remain unknown. With the discovery that BPH-1 could not provide protection against Biotype 2, there were concerns about a major plant hopper outbreak. To avoid such a scenario, genes from various sources and different resistance mechanisms are being explored. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) is the staple food of more than half of Earth's population. Brown planthopper (Nilaparvata lugens Stål, BPH) is a host-specific pest of rice responsible for inducing major losses in rice production. Utilizing host resistance to control N. lugens is considered to be the most cost-effective method. Therefore, the exploration of resistance genes and resistance mechanisms has become the focus of breeders' attention. During the long-term co-evolution process, rice has evolved multiple mechanisms to defend against BPH infection, and BPHs have evolved various mechanisms to overcome the defenses of rice plants. More than 49 BPH-resistance genes/QTLs have been reported to date, and the responses of rice to BPH feeding activity involve various processes, including MAPK activation, plant hormone production, Ca2+ flux, etc. Several secretory proteins of BPHs have been identified and are involved in activating or suppressing a series of defense responses in rice. Here, we review some recent advances in our understanding of rice–BPH interactions. We also discuss research progress in controlling methods of brown planthoppers, including cultural management, trap cropping, and biological control. These studies contribute to the establishment of green integrated management systems for brown planthoppers. [ABSTRACT FROM AUTHOR]

Popular rice varieties from India which exhibited field resistance against Brown Plant Hopper attack were selected to validate their resistance reaction. Genotyping using twenty-four gene-specific markers for BPH resistance was carried out. Besides this, phenotyping of morpho-economic traits along with resistance reaction was performed. Stepwise regression of phenotypic data showed that the traits viz. trichome number, leaf area and leaf number per tiller were significantly correlated to BPH damage score, while the traits, grains per panicle, tiller number, plant height and leaf number per plant contributed significantly towards seed yield. It was observed that there was a positive association between leaf area and BPH damage while trichome number was negatively associated, causing decreasing value in damage score. In the case of yield, except leaf number per plant, others traits showed a positive association. Further, PCA biplot analysis results confirmed the findings. Phenotypically, the rice variety Hasanta exhibited the highest BPH resistance followed by Jyotirmayee, Mahanadi, Konark and Pratap. Out of the twenty-four gene-specific markers, six markers exhibited polymorphism and RM247 showed the highest polymorphic information content (PIC) value. Cluster analysis of the varieties based on the marker data placed the variety Hasanta in a separate cluster, confirming its distinctness. Genotyping confirmed the genetic nature of BPH resistance in Hasanta variety. The cluster 2.2a included the highest number of varieties based on genetic similarity although it comprised of resistant, moderately resistant and susceptible types. This finding indicated that phenotypic variation within genotypic similar groups might be due to environment or different sources of origin. Hence, this phenotypic and genotypic variation among the genotypes would be useful for selecting elite and potential BPH-resistant donors in a crop improvement program. [ABSTRACT FROM AUTHOR]

Non-retroviral endogenous viral elements (nrEVEs) are widely dispersed throughout the genomes of eukaryotes. Although nrEVEs are known to be involved in host antiviral immunity, it remains an open question whether they can be domesticated as functional proteins to serve cellular innovations in arthropods. In this study, we found that endogenous toti-like viral elements (ToEVEs) are ubiquitously integrated into the genomes of three planthopper species, with highly variable distributions and polymorphism levels in planthopper populations. Three ToEVEs display exon‒intron structures and active transcription, suggesting that they might have been domesticated by planthoppers. CRISPR/Cas9 experiments revealed that one ToEVE in Nilaparvata lugens, NlToEVE14, has been co-opted by its host and plays essential roles in planthopper development and fecundity. Large-scale analysis of ToEVEs in arthropod genomes indicated that the number of arthropod nrEVEs is currently underestimated and that they may contribute to the functional diversity of arthropod genes. Non-retroviral endogenous viral elements are widely dispersed in eukaryotic genomes, but their functions remain largely unknown. Here, Huang et al show that one such element in planthoppers has been co-opted and contributes to insect fitness.. [ABSTRACT FROM AUTHOR]

In rice, biosynthesis of specialized metabolites active against insect herbivores is elusive. The major known defense metabolites in rice against the destructive phloem‐sucking herbivore brown planthoppers (BPH) (Nilaparvata lugens) are proteinase inhibitors, phenolamides and some terpenes (Xiao et al., 2012), which are induced during the invasion. Specifically, phenolamides were found to be induced upon herbivory with different feeding guild, including chewing and phloem‐sucking, but could only provide defense against phloem‐sucking BPH, though the clear mode of action of phenolamides has not been explored yet. Moreover, the jasmonic acid‐mediated modulation of biosynthesis of these specialized metabolites in rice is not elucidated yet. However, a recent study by Liu et al. (2023) demonstrated that sakuranetin, a phytoalexin in rice, was induced upon BPH invasion and showed significant detrimental effect on herbivore's performance by targeting their beneficial endosymbionts. This is the first report on a strong bioactive anti‐herbivore molecule observed in rice with an unusual mode of action. In this article, a view has been presented on this work, its impact and exceptionality. [ABSTRACT FROM AUTHOR]

The brown planthopper (BPH) is a highly destructive pest of rice, causing significant economic losses in various regions of South and Southeast Asia. Researchers have made promising strides in developing resistance against BPH in rice. Introgression line RPBio4918-230S, derived from Oryza nivara, has shown consistent resistance to BPH at both the seedling and adult stages of rice plants. Segregation analysis has revealed that this resistance is governed by two recessive loci, known as bph39(t) and bph40(t), contributing to 21% and 22% of the phenotypic variance, respectively. We later mapped the genes using a backcross population derived from a cross between Swarna and RPBio4918-230S. We identified specific marker loci, namely RM8213, RM5953, and R4M17, on chromosome 4, flanking the bph39(t) and bph40(t) loci. Furthermore, quantitative expression analysis of candidate genes situated between the RM8213 and R4M17 markers was conducted. It was observed that eight genes exhibited up-regulation in RPBio4918-230S and down-regulation in Swarna after BPH infestation. One gene of particular interest, a serine/threonine-protein kinase receptor (STPKR), showed significant up-regulation in RPBio4918-230S. In-depth sequencing of the susceptible and resistant alleles of STPKR from Swarna and RPBio4918-230S, respectively, revealed numerous single nucleotide polymorphisms (SNPs) and insertion–deletion (InDel) mutations, both in the coding and regulatory regions of the gene. Notably, six of these mutations resulted in amino acid substitutions in the coding region of STPKR (R5K, I38L, S120N, T319A, T320S, and F348S) when compared to Swarna and the reference sequence of Nipponbare. Further validation of these mutations in a set of highly resistant and susceptible backcross inbred lines confirmed the candidacy of the STPKR gene with respect to BPH resistance controlled by bph39(t) and bph40(t). Functional markers specific for STPKR have been developed and validated and can be used for accelerated transfer of the resistant locus to elite rice cultivars. [ABSTRACT FROM AUTHOR]

Brown planthopper (BPH), Nilaparvata lugens Stål, is a significant pest widely recognised for its detrimental impact on rice production. Biological agents, such as the entomopathogenic fungus Beauveria bassiana (Bals.) Vuill., can effectively control this pest. B. bassiana, known for its endophytic abilities, colonises various plant tissues. This research aims to assess B. bassiana’s colonosation capacity on rice plants and its impact on nymph mortality and BPH fecundity. Four isolates of B. bassiana (BbWS, Pb211, Td312, and BbJg) were used, each with conidial density of 108 conidia/ml. The application menthod involved soaking rice seeds in the fungus for 24 hours. The results showed that all B. bassiana isolates could successfully establish as endophytes within rice plants, colonising all tissue parts, with leaves exhibiting the highest fungal colonisation at 58%. Seed soaking with B. bassiana reduced eggs hatching by 23.88% and increased nymph mortality by 40%. The presence of B. bassiana in rice tissue also influenced BPH adults fecundity. Notably, the BbWS isolate demonstrated the most significant effectiveness in elevating nymph mortality and reducing BPH fecundity [ABSTRACT FROM AUTHOR]

The issue faced by rice farmers in Cirebon is the brown planthopper pest. Brown planthopper infestations can lead to crop damage of up to 40%, and many farmers experience crop failures. This research aims to determine the effect of the concentration of the active insecticide ingredients Nitenpyram + Pymetrozine in controlling the brown planthopper pest and the yield of rice plants (Oryza sativa L.) of Inpari 32 cultivar. The experimental site was at an altitude of approximately 3 meters above sea level. The experimental design used a randomized group design (RGD). There were 5 levels of insecticide concentration treatments and a control (no treatment), each repeated 5 times, resulting in 25 experimental plots. The treatment levels included A (Nitenpyram + Pymetrozine = 1 g/l), B (Nitenpyram + Pymetrozine = 0.75 g/l), C (Nitenpyram + Pymetrozine = 0.5 g/l), D (Nitenpyram + Pymetrozine = 0.25 g/l), and E (control). The experimental results show that the application of the active ingredient Nitenpyram + Pymetrozine effectively reduces the intensity of brown planthopper and other pest attacks on Inpari 32 rice plants, but it does not affect natural enemies. The Nitenpyram + Pymetrozine active ingredient does not cause harm to the rice plants themselves. The application of the Nitenpyram + Pymetrozine active ingredient has a significant impact on the yield of dried rice. A concentration of 1 g/l of the Nitenpyram + Pymetrozine active ingredient produces a yield of 12.79 kg per plot or equivalent to 5.116 tons per hectare. [ABSTRACT FROM AUTHOR]

Leucine-rich repeat receptor-like kinases (LRR-RLKs) are an important subfamily of receptor-like kinases (RLKs) in plants that play key roles in sensing different biotic and abiotic stress. However, the role of LRR-RLKs in herbivore-induced plant defense remains largely elusive. Here, we found that the expression of a rice gene, OsRLK7-1, was induced by mechanical wounding, but was slightly suppressed by the infestation of gravid females of brown planthopper (BPH, Nilaparvata lugens) or white-backed planthopper (WBPH, Sogatella furcifera). Through targeted disruption of OsRLK7-1 (resulting in the ko-rlk lines), we observed an augmentation in transcript levels of BPH-induced OsMPK3, OsWRKY30, OsWRKY33, and OsWRKY45, alongside heightened levels of planthopper-induced jasmonic acid, JA-isoleucine, and abscisic acid in plant tissues. These dynamic changes further facilitated the biosynthesis of multiple phenolamides within the rice plants, culminating in an enhanced resistance to planthopper infestations under both lab and field conditions. In addition, knocking out OsRLK7-1 impaired plant growth and reproduction. These results suggest that OsRLK7-1 plays an important role in regulating rice growth, development, and rice-planthopper interactions. [ABSTRACT FROM AUTHOR]

Plant defense against herbivores is costly and often associated with growth repression. The phytohormone jasmonate (JA) plays a central role in prioritizing defense over growth during herbivore attack, but the underlying mechanisms remain unclear. When brown planthoppers (BPH, Nilaparvata lugens) attack rice (Oryza sativa), growth is dramatically suppressed. BPH infestation also increases inactive gibberellin (GA) levels and transcripts of GA 2-oxidase (GA2ox) genes, 2 (GA2ox3 and GA2ox7) of which encode enzymes that catalyze the conversion of bioactive GAs to inactive GAs in vitro and in vivo. Mutation of these GA2oxs diminishes BPH-elicited growth restriction without affecting BPH resistance. Phytohormone profiling and transcriptome analyses revealed that GA2ox-mediated GA catabolism was enhanced by JA signaling. The transcript levels of GA2ox3 and GA2ox7 were significantly attenuated under BPH attack in JA biosynthesis (allene oxide cyclase [aoc]) or signaling-deficient (myc2) mutants. In contrast, GA2ox3 and GA2ox7 expression was increased in MYC2 overexpression lines. MYC2 directly binds to the G-boxes in the promoters of both GA2ox genes to regulate their expression. We conclude that JA signaling simultaneously activates defense responses and GA catabolism to rapidly optimize resource allocation in attacked plants and provides a mechanism for phytohormone crosstalk. Jasmonate-mediated gibberellin catabolism is partially responsible for brown planthopper–elicited growth inhibition in rice. [ABSTRACT FROM AUTHOR]

This article discusses a study conducted on the genes PGRP-LC and Toll-1 in the insect species Nilaparvata lugens, also known as the brown planthopper. The researchers used RNA interference (RNAi) to suppress the expression of these genes and found that suppressing PGRP-LC resulted in increased mortality rates in insects infected with live bacteria. However, suppressing Toll-1 did not have a significant effect on mortality rates. The study suggests that RNAi could be a valuable tool for controlling this destructive pest species. [Extracted from the article]

The most devastating insect pest of rice, Brown plant hopper (BPH) (Nilaparvata lugens Stal.) feeds on the rice plant and results in huge yield loss. Breeding of resistant cultivars is more economical and eco-friendlier than use of chemical pesticides. Rice cultivars with improved resistance to disease and pest are developed with pyramiding techniques to incorporate the stronger resistance genes in single plant. In this study, CO51, a popular elite variety of Tamil Nadu, improved with introgression of bacterial blight and blast resistance genes was used as a recurrent parent and BPH resistance genes were introgressed in it using marker-assisted selection (MAS) method of breeding. The lines having multiple resistance genes were evaluated using foreground and agronomic trait selection and forwarded toBC2 F4 generation. The bioassay of selected twenty-seven lines showed either single or both gene introgression enhanced resistance than the recurrent parent. [ABSTRACT FROM AUTHOR]

Rice field bunds and edges can act as near crop habitats, available for planting flowering plants to attract and conserve the natural enemies. We evaluated the effect of ecological engineering on the incidence of Brown Planthopper (BPH), Nilaparvata lugens (Stål) (Hemiptera; Delphacidae) and the abundance of its predators in the rice variety Pusa Basmati-1121. Plots included the oilseed crops viz. sesamum, sunflower and soybean, with plantings of flowering crops marigold, balsam and gaillardia as bund flora around the edges of rice plots. Ecologically engineered plots contained both crops+flowers and resulted in a significantly reduced BPH population per hill in rice plots for 2019 (6.3) and 2020 (9.4) compared to the control plots (9.8 and 14.4). Ecologically engineered plots also witnessed the delayed appearance of BPH during each growing season. Peak BPH populations are lower in the ecologically engineered plots than in the control grounds. Furthermore, the activity of natural enemies, viz., spiders, mirid bugs and rove beetles was the highest in rice fields planted with oilseed crops like sesamum, sunflower and soybean. Olfactory response studies showed that the attraction response of spiders toward sesamum and balsam leaves was more significant than in other crop plants. Rice yield was enhanced in plots planted with crops+flowers during both seasons compared to control plots. Planting of oilseed crops plants such as sesamum, sunflower and soybean with flowering crops such as marigold, balsam and gaillardia as bund flora on the bunds around the main rice field enhanced the natural enemy activity, suppressed the planthopper population, and increased yields. Based on the results, we recommend including ecological engineering techniques as one of the management components in the Integrated Pest Management programme for rice crops. [ABSTRACT FROM AUTHOR]

Fatty acid synthase (FAS) is a multifunctional enzyme that plays an important role in the formation of fatty acids. The fatty acids take part in many processes, such as cell signaling and energy metabolism, and in insects they are important in both cuticular hydrocarbon (CHC) formation and reproduction. Here we characterized the sequence structure and function of an FAS from the small brown planthopper (SBPH), Laodelphax striatellus. The full‐length open reading frame (ORF) sequence of LsFAS1 was 7122 bp, encoding a predicted protein of 2373 amino acid residues. There were 7 functional domains in the LsFAS1 protein sequence. Gene expression screening by real‐time quantitative polymerase chain reaction (RT‐qPCR) showed that LsFAS1 was expressed in all developmental stages. Relative expression was highest at the 4th‐instar and female adult stages. Among different tissues, the expression level of LsFAS1 in the ovary was the highest. Phylogenetic analysis showed that LsFAS1 clustered in a clade with 2 FASs from Nilaparvata lugens. Furthermore, these 3 FASs are related to cockroach BgFAS and locust LmFAS. After RNA interference‐mediated knock‐down, most treated insects died at eclosion. In addition, the lifespan of dsFAS1‐treated female adults was shorter than that of the dsGFP‐injected control, and offspring production decreased. Also, the expression of vitellogenin (Vg) and vitellogenin receptor (VgR) genes decreased. Virgin females dissected at days 2 and 4 post‐eclosion showed many matured oocytes in planthoppers treated with dsGFP but not with dsFAS1. These data highlight the importance of LsFAS1 in SBPH, including a role in reproduction. [ABSTRACT FROM AUTHOR]

The current research was taken up at Institute of Biotechnology (IBT), PJTSAU, Hyderabad Telangana, India in kharif from August to November, 2021 to access the parental polymorphism between 10-3 and Telangana Sona. 10-3, an Assam landrace, is a bold grain rice variety with high BPH resistance to biotype-4. Whereas, Telangana Sona (RNR 15048) is a short and slender grain variety of rice that is popular among farmers and consumers across Telangana and other Indian states due to its high yield and low glycemic index. Despite being blast resistant, Telangana Sona is susceptible to the insect pest Brown Plant hopper (BPH) Nilaparvata lugens (Stål). The present study aimed to characterize the parental polymorphism between 10–3 and Telangana sona to facilitate mapping of genetic loci linked with BPH resistance in the 10–3 and to optimize the retention of favourable alleles from Telangana sona during marker assisted backcross breeding. Eight hundred and sixteen highly variable Simple Sequence Repeats (SSRs) including thirty-five BPH linked markers covering 12 chromosomes were used to assess DNA polymorphism between 10-3 and Telangana Sona. Out of 816 markers screened, 97 (11.89%) were found to be polymorphic between 10–3 and Telangana Sona of which, 82 were genomic SSRs and 15 were BPH linked markers. Chromosome 6 exhibited highest polymorphism percentage with a value of 30%, indicating that this chromosome is useful in studying parental variation and lowest polymorphism percentage found on chromosome 5 (3.49%). These 97 polymorphic markers will help in construction of linkage map for identifying QTLs linked with BPH resistance and for marker assisted backcrossing breeding in Telangana Sona. [ABSTRACT FROM AUTHOR]

Rice serves as the primary food source for nearly half of the global population, with Asia accounting for approximately 90% of rice production worldwide. However, rice farming faces significant losses due to pest attacks. To prevent pest infestations, it is crucial to apply appropriate pesticides specific to the type of pest in the field. Traditionally, pest identification and counting have been performed manually using sticky light traps, but this process is time-consuming. In this study, a machine vision system was developed using a dataset of 7328 high-density images (1229 pixels per centimetre) of planthoppers collected in the field using sticky light traps. The dataset included four planthopper classes: brown planthopper (BPH), green leafhopper (GLH), white-backed planthopper (WBPH), and zigzag leafhopper (ZIGZAG). Five deep CNN models—ResNet-50, ResNet-101, ResNet-152, VGG-16, and VGG-19—were applied and tuned to classify the planthopper species. The experimental results indicated that the ResNet-50 model performed the best overall, achieving average values of 97.28% for accuracy, 92.05% for precision, 94.47% for recall, and 93.07% for the F1-score. In conclusion, this study successfully classified planthopper classes with excellent performance by utilising deep CNN architectures on a high-density image dataset. This capability has the potential to serve as a tool for classifying and counting planthopper samples collected using light traps. [ABSTRACT FROM AUTHOR]

Insect pests pose major threat to the rice production and amongst these, brown plant hopper, Nilaparvata lugens (Stal) and whitebacked planthopper, Sogatella furcifera (Horvath) are the major culprit for huge economic crop losses of rice. The efficacy of newer insecticide flonicamid (Ulala 50 WG) against these insect pests with an aim of least disturbance to ecosystem and compared with the checks pymetrozine (Chess 50 WG) and imidacloprid was evaluated. The insecticides were applied when population exceeded economic threshold level (ETL) of 5 planthoppers per hill. The results revealed that flonicamid @ 75 g ai ha-1 for the management of planthoppers in rice/basmati was statistically at par with the check pymetrozine applied @ 150 g ai ha-1 but significantly superior to imidacloprid @ 25 g ai ha-1. [ABSTRACT FROM AUTHOR]

Simple Summary: The control of rice planthoppers (RPH) in Asian countries has relied upon chemical insecticides for several decades. The reliance no longer continues in the rice–aquaculture coculture and rotation systems emerging as high-profit agriculture in Southern China because chemical control is prohibited in these systems to prevent aquaculture products from contamination with chemical residues. In this field study, the RPH population in three rice–shrimp rotation paddy fields was effectively controlled for four weeks at the critical tillering to flowing stages after two fungal insecticides were sprayed twice at the recommended rate. For either fungal insecticide, the sprays applied after 5:00 p.m. to avoid solar UV irradiation were consistently more efficacious against the RPH population than those before 10:00 a.m. These results indicate the feasibility of fungal insecticides for RPH control in the rice–shrimp rotation fields and the importance of timing the application of fungal insecticides to avoid solar UV exposure for enhanced RPH control during the summer months. Thechemical control of rice planthoppers (RPH)is prohibited in annual rice–shrimp rotation paddy fields. Here, the fungal insecticides Beauveria bassiana ZJU435 and Metarizhium anisoplae CQ421 were tested for control of RPH populations dominated by Nilaparvata lugens in three field trials. During four-week field trials initiated from the harsh weather of high temperatures and strong sunlight, the rice crop at the stages from tillering to flowering was effectively protected by fungal sprays applied at 14-day intervals. The sprays of either fungal insecticide after 5:00 p.m. (solar UV avoidance) suppressed the RPH population better than those before 10 a.m. The ZJU435 and CQ421 sprays for UV avoidance versus UV exposure resulted in mean control efficacies of 60% and 56% versus 41% and 45% on day 7, 77% and 78% versus 63% and 67% on day 14, 84% and 82% versus 80% and 79% on day 21, and 84% and 81% versus 79% and 75 on day 28, respectively. These results indicate that fungal insecticides can control RPH in the rice–shrimp rotation fields and offer a novel insight into the significance of solar-UV-avoiding fungal application for improved pest control during sunny summers. [ABSTRACT FROM AUTHOR]

Rice is an indispensable crop in East and Southeast Asia, and the study of its biological characteristics has important value. We observed that different cultivars of rice have different levels of resistance to the brown planthopper (BPH), Nilaparvata lugens. In this study, transcriptome sequencing was used to analyze the differentially expressed genes (DEGs) of three rice varieties caused by BPH damage combined with physical stimulation and controls. We performed weighted correlation network analysis (WGCNA) and found a module positively related to physical stimulation. KEGG analysis showed that this module is strongly related to the ribosome pathway. Through comparative analysis with controls, we found the differential genes of each cultivar after BPH damage; through trend analysis, we found the differential genes shared by the three varieties after BPH damage. The KEGG/GO enrichment analysis of these genes found that they are mainly functionally concentrated in signal transduction, redox reactions, etc. The results of this research will be helpful to study the molecular mechanism of the BPH-rice interaction, identify resistance genes, and facilitate further studies on molecular resistance breeding and pest control. [ABSTRACT FROM AUTHOR]

The rice hoppers viz., brown plant hopper (BPH) Nilaparvata lugens (Stal), white-backed planthopper (WBPH) Sogatella furcifera (Horvath) and green leafhopper (GLH) Nephotettix virescens Distant cause loss in rice and the damage is influenced by plant growth stages. Field experiment has been conducted in this study to evaluate the effect of the growing stages on the incidence of these hoppers at the Agricultural Research Farm, Banaras Hindu University, Varanasi, Uttar Pradesh, India during kharif 2018 and 2019. The results revealed that the incidence is significantly varying among the growth stages, and positively correlated (p < 0.05). Nilaparvata lugens and S. furcifera are the most abundant during the maximum tillering to booting stage. In contrast that of N. virescens peaked during the booting to flowering stage. [ABSTRACT FROM AUTHOR]

The efficacy of foliar application of benzpyrimoxan 10SC @ 50, 75, 100, 125 and 150 g a.i./ habesides the insecticidal checks imidacloprid 17.8SL @ 25 g a.i./ ha and buprofezin 25SC @ 187.5 g a.i./ ha was evaluated against the brown planthopper (BPH) Nilaparvata lugens (Stal.) and the white backed planthopper (WBPH) Sogatella furcifera (Horvath) on rice during kharif 2017 and 2018 at the Punjab Agricultural University, Ludhiana. Experimental design consisted of random blocks in three replications. Two years data revealed that benzpyrimoxan 10SC @ 100 g a.i./ ha is significantly superior against the N. lugens and S. furcifera complex. Benzpyrimoxan 10SC @ 100 g a.i./ ha gave significantly higher yield (34.17 q/ ha) than its lower doses but was statistically at par with its higher doses. Non-significant differences in number of spiders/ hill among treated plots and untreated check at 10- and 15-DAS indicated the safety of benzpyrimoxan. [ABSTRACT FROM AUTHOR]

Background: 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. Results: 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. Conclusion: The results reveal the biological functions of ThrRS in N. lugens in addtion to its 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. [ABSTRACT FROM AUTHOR]

BACKGROUND: The brown planthopper, Nilaparvata lugens, is considered the most destructive pest of rice in many Asian countries including China. Use of pymetrozine in insect resistance management (IRM) has been one strategy to control this pest. In this study, we reported the status of pymetrozine resistance in Nilaparvata lugens (Stål) collected from China over the period 2017–2021 and selected a strain of N. lugens resistant to pymetrozine and evaluated the cross‐resistance, inheritance and fitness costs of the resistance. RESULTS: Monitoring data (2017–2021) showed that field populations of N. lugens in China developed moderate‐ to high‐level pymetrozine resistance during these 5 years. By continuous selection with pymetrozine in the lab, the pymetrozine selected N. lugens strain (Pym‐R98) developed a 225.2‐fold resistance compared to a susceptible strain. The Pym‐R98 strain showed high cross‐resistance to dinotefuran (66.6‐fold) and low cross‐resistance to nitenpyram (5.2‐fold) and sulfoxaflor (5.8‐fold). Inheritance pattern analysis of Pym‐R93 revealed that resistance to pymetrozine was polygenic, autosomal and incompletely dominant. Fitness costs of pymetrozine resistance were present in Pym‐R90 and WA2020 strains with a relative fitness of 0.72 and 0.60, respectively. The developmental duration of Pym‐R90 and WA2020 was significantly longer and hatchability was significantly lower compared to pymetrozine‐susceptible strain (Pym‐S). CONCLUSIONS: N. lugens has developed high level of resistance to pymetrozine. Pymetrozine‐resistance brown planthopper had cross‐resistance with some of neonicotinoids such as dinotefuran, nitenpyram and sulfoxaflor. The autosomal, incompletely dominant and polygenic resistance to pymetrozine in N. lugens and the fitness costs associated with this resistance can be exploited in IRM strategies to preserve the lifetime of pymetrozine for control of N. lugens in China. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The brown planthopper (BPH) Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) is one of the most destructive rice pests in Asia. The application of insect-resistant rice cultivars is currently one of the principal means of controlling BPH. Understanding the physiological response mechanisms of BPH feeding on insect-resistant rice is the key for maintaining rice yield. Here, we measured the ecological fitness and analyzed the whole-body transcriptome and metabolome of BPH reared on susceptible cultivar Taichung Native 1 (TN1) and resistant cultivar Rathu Heenati (RH). Our results showed that RH significantly decreased the survival rate, female adult weight, honeydew secretion, the number of eggs laid per female and fat content of BPH. We identified 333 upregulated and 486 downregulated genes in BPH feeding on RH. These genes were mainly involved in energy metabolism, amino acid metabolism, hormone synthesis and vitamin metabolism pathways. We also detected 145 differentially accumulated metabolites in BPH reared on RH plants compared to BPH reared on TN1 plants, including multiple carbohydrates, amino acids, lipids, and some nucleosides. Combined analyses of transcriptome and metabolome showed that five pathways, including starch, sucrose, and galactose metabolism, were altered. The network for these pathways was subsequently visualized. Our results provide insights into the mechanisms of metabolite accumulation in BPH feeding on the RH rice variety. The results could help us better understand how insect-resistant rice cultivars combat BPH infestation, which is important for the comprehensive management of BPH. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.,) plants release a complex profile of volatile organic compounds. Present study investigates the differences in volatile compounds from four rice landraces viz., Karuthakar, Norungan, Thavala Kanan and Varappu Kudaichan each under four conditions like healthy, mechanically damaged, and the ones infested by the brown plant hopper Nilaparvata lugens Stal and yellow stem borer Scirpophaga incertulas (Wlk.). The volatiles were collected using air entrainment method and characterized by the GCMS. Statistical analysis tools like clustering, principal component analysis and partial least square discriminant analysis were applied. Clear differences among the treatments were observed and certain volatile compound groups like terpenoids (squalene), unsaturated fatty acids (n-hexadecanoic, tetradecanoic and pentadecanoic acids), alkanes (heptacosane, tetracosane) were found. The statistical test of Partial Least Square Discriminant Analysis was found to be satisfactory in determining the compounds responsible for variations in treatments. [ABSTRACT FROM AUTHOR]

Simple Summary: Rice is often attacked by several herbivores and plant pathogens at the same time. Public research has mainly focused on enhancing rice resistance against these biotic stresses by selecting rice lines with resistance genes during breeding programs. However, rice resistance to biotic stresses is also affected by soil nutrients, including available nitrogen and silicon. Nitrogen tends to reduce resistance, but silicon can increase resistance. We assessed the effects of combining soil silicon with host plant resistance against rice planthoppers, blast disease, and bacterial blight disease. We used pure silicon (SiO2) to avoid the confounding effects of nutrients associated with silicates. We also assessed the effects of nitrogenous fertilizer on silicon-augmented resistance to planthoppers. We found that high nitrogen diminishes the capacity of soil silicon and host resistance to reduce planthopper fitness (i.e., nitrogen was antagonistic); but that silicon counters nitrogen-related reductions in rice antixenosis defenses (e.g., repellency) against gravid female planthoppers (i.e., an additive effect of silicon and resistance). Silicon augmented resistance against blast and bacterial blight, but the effects were most apparent on susceptible varieties. Plants infected with bacterial blight generally grew larger in silicon amended soils. We discuss how silicon improves seedling quality by augmenting broad-spectrum resistance. Soil silicon enhances rice defenses against a range of biotic stresses. However, the magnitude of these effects can depend on the nature of the rice variety. We conducted a series of greenhouse experiments to examine the effects of silicon on planthoppers (Nilaparvata lugens [BPH] and Sogatella furcifera [WBPH]), a leafhopper (Nephotettix virescens [GLH]), blast disease (Magnaporthe grisea) and bacterial blight (Xanthomonas oryzae) in susceptible and resistant rice. We added powdered silica gel (SiO2) to paddy soil at equivalent to 0.25, 1.0, and 4.0 t ha−1. Added silicon reduced BPH nymph settling, but the effect was negligible under high nitrogen. In a choice experiment, BPH egg-laying was lower than untreated controls under all silicon treatments regardless of nitrogen or variety, whereas, in a no-choice experiment, silicon reduced egg-laying on the susceptible but not the resistant (BPH32 gene) variety. Stronger effects in choice experiments suggest that silicon mainly enhanced antixenosis defenses. We found no effects of silicon on WBPH or GLH. Silicon reduced blast damage to susceptible and resistant (Piz, Piz-5 and Pi9 genes) rice. Silicon reduced damage from a virulent strain of bacterial blight but had little effect on a less virulent strain in susceptible and resistant (Xa4, Xa7 and Xa4 + Xa7 genes) varieties. When combined with resistance, silicon had an additive effect in reducing biomass losses to plants infested with bacterial blight (resistance up to 50%; silicon 20%). We discuss how silicon-containing soil amendments can be combined with host resistance to reduce biotic stresses in rice. [ABSTRACT FROM AUTHOR]

Two hundred and one rice EMS (Ethyly methanesulfonate) N22 mutants were mass screened to check their resistance towards rice planthoppers viz., brown planthopper, BPH, Nilaparvata lugens (Stål) and whitebacked planthopper WBPH Sogatella furcifera (Horvath) by standard seed box technique at ICAR-Indian Institute of Rice Research, Hyderabad. Out of these N22 mutants screened, thirty one mutants were resistant to BPH and exhibited a damage score ranging from 1.0- 5.0 and the remaining one hundred and seventy mutants were found susceptible with a damage score of 5.1-9.0. Out of thirty one BPH resistant mutants, twelve mutants were resistant and nineteen mutants were moderately resistant. In case of WBPH screening, forty four mutants were resistant and exhibited a damage score (DS) ranging from 0.0 to 5.0 and the remaining one hundred and fifty seven mutants were susceptible with a damage score of 5.1 to 9.0. Out of forty four WBPH resistant mutants, three mutants viz., NH 663, NH 4963 and NH 4613 were highly resistant, twenty mutants were resistant, and twenty one mutants were moderately resistant. In addition, twenty one mutants were resistant to both BPH and WBPH. The identified resistant germplasm accessions can be used as donors in the breeding programmes to develop planthopper resistant varieties. [ABSTRACT FROM AUTHOR]

The feeding of piercing-sucking insect herbivores often elicits changes in their host plants that benefit the insect. 1 In addition to thwarting a host's defense responses, these phloem-feeding insects may manipulate source-sink signaling so as to increase resources consumed. 2,3 To date, the molecular mechanisms underlying herbivore-induced resource reallocation remain less investigated. Brown planthopper (BPH), an important rice pest, feeds on the phloem and oviposits into leaf sheaths. BPH herbivory increases sugar accumulations 5-fold in the phloem sap of leaf sheaths and concurrently induces the expression of two clade III SWEET genes, SWEET13 and SWEET14 , in leaf tissues, but not in leaf sheaths of attacked rice plants. Mutations of both genes by genome editing attenuate resistance to BPH without alterations of known chemical and physical defense responses. Moreover, BPH-elicited sugar levels in the phloem sap were significantly reduced in sweet13/14 mutants, which is likely to attenuate BPH feeding behavior on sweet13/14 mutants. In one of the two field seasons tested, the sweet13/14 mutants showed comparable yield to wild types, and in the other season, the mutants demonstrated stronger BPH resistance. These preliminary results suggested that the mutations in these SWEET transporters could enhance BPH resistance without yield penalties. Given that sweet13 / 14 mutants also exhibit resistance to bacterial blight pathogen, Xanthomonas oryzae pv. oryzae , these SWEET genes could serve as excellent molecular targets for the breeding of resistant rice cultivars. [Display omitted] • BPH infestation activates SWEET13/14-mediated sugar transport in rice source leaves • Mutations of SWEET13/14 enhance resistance to BPH and Xoo without yield penalty • The sugar content of phloem sap affects BPH feeding behavior Yu et al. show that brown planthopper (BPH) infestations of rice leaf sheaths upregulate SWEET13 and SWEET14 genes in leaves, increasing sugar concentrations in the phloem sap and facilitating BPH feeding. Lab and field experiments revealed that sweet13 / 14 mutants had enhanced resistance to both bacterial blight and BPH without yield penalty. [ABSTRACT FROM AUTHOR]

RNA interference (RNAi) is an emerging tool in crop protection by exogenous applications of double-stranded RNAs (dsRNAs) to silence the expression of essential pest genes. Nevertheless, topical delivery of dsRNAs to sap-sucking insects is a major challenge due to the insufficient infiltration and translocation to plant vascular. Foliar sprayed layered double hydroxide (LDH) showed insufficient translocation in plant vascular and the supplement of surfactants caused phytotoxicity to plant. Thus, in the present study, LDH was transformed from hydrophilic to amphiphilic by fatty acids modification to obtain a surfactant-like LDH (LDHS) with good leaf adhesion, translocation and excellent biocompatibility. LDHS was synthesized via a mild hydrothermal method using MgCl 2 , FeCl 3 and palm oil as the precursors, resulting in LDH coated with long-chained carboxylates as hydrophobic tails. LDHS showed good binding affinity with dsRNA and high affinity to rice leaves. Once loaded with dsRNA, LDHS were shown to enhance the uptake of dsRNA to rice brown planthoppers (Nilaparvata lugens) through a direct spray. Moreover, in planta, dsRNA-LDHS exhibited translocation from rice leaves to vascular bundles and finally into the planthoppers, delivered 2.5-fold higher dsRNA and caused higher mortalities of planthoppers than hydrophilic LDH with adjuvants. Herein we generate and validate a platform that can deliver dsRNA through either direct sprays or sprayed living plant to brown planthoppers with high efficiency, low toxicity and adjuvant-free. Consequently, it is a green potential selection using amphiphilic LDHS agents instead of the conventional gene carriers to prepare biopesticide nanoparticles. [ABSTRACT FROM AUTHOR]

Simple Summary: In recent years, the atmospheric CO2 concentration was increasing continuously, which has led to the change in the photosynthesis and chemical composition of rice plants. The growth and development of brown planthopper (BPH) Nilaparvata lugens are further affected. Plants release volatile organic compounds (VOCs) to mediate intra- and inter-specific interactions with other organisms in the surrounding environment. Therefore, here we aim to explore the effect of rice VOCs on the host selection ability of BPH under elevated CO2. Among the identified thirty-six rice VOCs, the contents of heptadecane, linalool and limonene from rice plants were significantly decreased under elevated CO2. Moreover, we found that the VOCs of rice damaged by BPH were also changed. Undecane, hexadecane, nonanal and 2,6-diphenylphenol from BPH-damaged rice plants under elevated CO2 were all significantly higher than those from healthy rice plants, which might lead to enhancement of the host selection ability of BPH, eventually aggravating the damage caused by BPH. However, the role of these VOCs in host selection ability of BPH is not clear, and more experiments are needed to verify their function. It is predicted that plant volatile organic compounds (VOCs) are affected by the atmospheric CO2 levels rising globally, which further affects the interaction between plants and herbivorous insects, especially the host selection behavior of herbivorous insects. In this study, the effects of elevated CO2 on the host-selection behavior of the brown planthopper (BPH) Nilaparvata lugens, and the emission of VOCs from the healthy and BPH-damaged rice plants were studied simultaneously to make clear the population occurrence of BPH under global climate change. Compared with ambient CO2, elevated CO2 significantly increased the host selection percent of BPH for the healthy (CK) and BPH-damaged rice plants, and the host selection percent of BPH for the BPH-damaged rice plants was significantly higher than that for the healthy rice plants under elevated CO2, which might be regulated by the transcription levels of OBP1, OBP2 and CSP8 in BPH due to the upregulated transcriptional levels of these three genes of BPH under elevated CO2. In addition, we analyzed and quantified the emission of VOCs in rice plants grown under ambient CO2 and elevated CO2 by GS-MS. A total of 36 VOCs from rice plants were identified into eight categories, including alkanes, alkenes, alcohols, aldehydes, ketones, esters, phenols and aromatic hydrocarbons. Elevated CO2 significantly decreased the contents of heptadecane, linalool and limonene from rice plants compared with ambient CO2. Besides, the contents of linalool, phytol, decanal, 1-methyldecalin and 2,6-diphenylphenol from BPH-damaged rice plants under ambient CO2, and undecane, hexadecane, nonanal and 2,6-diphenylphenol from BPH-damaged rice plants under elevated CO2 were all significantly higher than those from healthy rice plants. The percentage composition of phenols was positively correlated with the host selection rate of BPH. Our study indicates that elevated CO2 is beneficial to promote the host selection ability of BPH for rice plants damaged by BPHs due to the changed plant VOCs. [ABSTRACT FROM AUTHOR]

Efficacy of a new combination insecticide against rice brown plant hopper (BPH) Nilaparvata lugens Stal revealed that among all the treatments, significant reduction in the incidence (76.91% reduction over control) and higher grain yield (5.37 ton/ ha) was obtained with buprofezin 24%+ fipronil 40%SC (MAIRM-10) @ 875 ml/ ha. It was at par with buprofezin 24%+ fipronil 40%SC (MAIRM-10) @ 750 ml/ ha followed by buprofezin 25%SC @ 800 ml/ ha. Although maximum grain yield was obtained from buprofezin 24%+ fipronil 40%SC (MAIRM-10) @ 875 ml/ ha, maximum cost benefit in term of ICBR was observed with buprofezin 24%+ fipronil 40%SC (MAIRM-10) @ 750 ml/ ha (1:6.11) besides considering the environmental effect. Buprofezin 24%+ fipronil 40%SC (MAIRM-10) @ 750 ml/ ha was found to be most optimum one for BPH management. [ABSTRACT FROM AUTHOR]

Summary: The planthopper resistance gene Bph6 encodes a protein that interacts with OsEXO70E1. EXO70 forms a family of paralogues in rice. We hypothesized that the EXO70‐dependent trafficking pathway affects the excretion of resistance‐related proteins, thus impacting plant resistance to planthoppers. Here, we further explored the function of EXO70 members in rice resistance against planthoppers.We used the yeast two‐hybrid and co‐immunoprecipitation assays to identify proteins that play roles in Bph6‐mediated planthopper resistance. The functions of the identified proteins were characterized via gene transformation, plant resistance evaluation, insect performance, cell excretion observation and cell wall component analyses.We discovered that another EXO70 member, OsEXO70H3, interacted with BPH6 and functioned in cell excretion and in Bph6‐mediated planthopper resistance. We further found that OsEXO70H3 interacted with an S‐adenosylmethionine synthetase‐like protein (SAMSL) and increased the delivery of SAMSL outside the cells. The functional impairment of OsEXO70H3 and SAMSL reduced the lignin content and the planthopper resistance level of rice plants.Our results suggest that OsEXO70H3 may recruit SAMSL and help its excretion to the apoplast where it may be involved in lignin deposition in cell walls, thus contributing to rice resistance to planthoppers. [ABSTRACT FROM AUTHOR]

Triflumezopyrim (TMP), a mesoionic insecticide, is commonly used for controlling planthoppers in rice. However, the relationship between the TMP residue and toxicity against brown planthoppers (BPHs) has not been studied in detail. We are reporting the dissipation of TMP from rice plant and soil under field conditions. The median lethal dose and median lethal concentration were 0.036 ng per insect and 0.525 mg L−1, respectively. TMP at recommended dose (25 g a.i. ha−1) recorded 1.25 live BPH per hill as against 25.5 per hill in control at 14 days after treatment. TMP was considered to be harmless to the natural enemies, namely, Cyrtorhinus lividipennis and Lycosa pseudoannulata in the rice ecosystem. The residue of TMP from rice plant and soil was estimated using the QuEChERS method using three different doses (12.5, 25, and 50 g a.i. ha−1). The limit of quantitation (LOQ) of TMP in plant and soil was 5 µg kg−1 and 1 µg kg−1, respectively. The maximum content of TMP in soil was less than 1% that of plant content on day 1. The dissipation pattern of TMP both from plant and soil was better explained by the first-order double-exponential decay model (FODED) as compared to the first-order kinetic model. Overall, the half-lives of TMP were ranged from 2.21 to 3.02 days in plant tissues and 3.78 to 4.79 days in soil as per the FODED model. Based on the persistence and toxicity of TMP, we could conclude that TMP will be effective against BPH up to 7–10 days after application. Triflumezopyrim with reasonable persistence and high efficacy could be recommended as an alternate pesticide in BPH management in rice. [ABSTRACT FROM AUTHOR]

The brown planthopper (Nilaparvata lugens Stål, BPH) is one of the most devastating insect pests of rice (Oryza sativa L.), but BPH populations have varying degrees of virulence to rice varieties carrying different resistance genes. To help efforts to characterize these variations we applied bulked segregant RNA sequencing (BSR-seq) to identify differentially expressed genes (DEGs) and genetic loci associated with BPH virulence to YHY15 rice plants carrying the resistance gene Bph15. BPHs that are highly virulent or avirulent to these plants were selected from an F2 population to form two contrasting bulks, and BSR-seq identified 751 DEGs between the bulks. Genes associated with carbohydrate, amino acid and nucleotide metabolism, the endocrine system, and signal transduction were upregulated in the avirulent insects when they fed on these plants. The results also indicated that shifts in lipid metabolism and digestive system pathways were crucial for the virulent BPHs' adaptation to the resistant rice. We identified 24 single-nucleotide polymorphisms (SNPs) in 21 genes linked with BPH virulence. Possible roles of genes apparently linked to BPH virulence are discussed. Our results provide potentially valuable information for further studies of BPH virulence mechanisms and development of robust control strategies. [ABSTRACT FROM AUTHOR]

In the present study, glasshouse screening was carried out to evaluate 532 rice genotypes to identify new sources of resistance against brown plant hopper, Nilaparvata lugens (Stal.) by following standard seed box screening technique (SSST) and standard evaluation system (IRRI, 1992). In mass screening replicated tests, 6 genotypes were identified as highly resistant and 36 as resistant. Moderate resistance was observed in 112 varieties. The remaining genotypes were categorized in susceptible and highly susceptible groups. Further the 10 selected genotypes having 5 resistant and susceptible lines including standard resistant and susceptible checks were screened by nymphal preference / non-preference test and feeding behavior test. Among the selected lines, resistant genotypes were relatively less preferred by nymphs against the susceptible genotypes. The lowest number of nymphs settled was recorded on resistant genotype PHHS17 (2.62) followed by Ptb 33 (3.67), BPT 2766 (3.83), RP 5995 Bphk17-5 (4.67), NHSH16 (4.83) compared to susceptible (12.36-16.33) at 72 hour of infestation. There was a positive correlation between the number of nymphs settled and the damage score. Likewise, the results of probing behavior test on selected genotypes indicated that resistant genotypes received more number of probing punctures than the susceptible genotypes even at different plant age (20, 40, 60, 80 days old). BPH produced highest number of probing marks on PHHS17 (55.67/plant). On resistant genotypes, feeding marks ranged from 30.64 to 36.17, 37.89 to 53.67, and 45.40 to 55.50 on 20, 40 and 60 day old plants, respectively which were significantly lower than susceptible genotypes (18.67 to 22.41 on 80 days old plants). There was no significant difference in probing marks between 60 and 80 days old plant. Plant resistance appeared to be increasing with increasing age irrespective of resistance level. [ABSTRACT FROM AUTHOR]

This study aims to monitor and determine the level of resistance of N. lugens to fenobucarb and imidacloprid, to analyse of the specific activities of asetylcholinesterase, Glutation S-Transferase, esterase, and to determine sensitivity of resistant N. lugens to the neem oil. Resistance tests were conducted on a field population from Cipunagara, Subang, West Java, Indonesia, and a standard population originating from Banyuwangi, East Java, that was obtained from the Indonesian Center for Rice Research. Synthetic and neem Insecticides were applied using the leaf-stem dipping method. The resistance ratio obtained by comparing the LC50 value of the field population with the standard. The test insects were considered to be resistant to synthetic insecticide if they had a resistance ratio (RR) of more than 4, indicated resistance if RR ≥1, and susceptible to neem if has RR <1. The results of the research showed that the N. lugens population of Cipunagara indicated resistance to fenobucarb (RR = 2.43), while it was clearly resistance to imidacloprid (RR = 13.95). Specific activities of the acetylcholinesterase and Glutathione S-Transferase of the N. lugens Cipunagara populations were higher than the standard, while the esterase specific activity was lower. These two enzymes are responsible for the resistance of N. lugens to fenobucarb and imidacloprid. Nevertheless, the N. lugens population of Cipunagara was susceptible to neem (RR <1) that never been reported before. Therefore, it is important to know the change in the sensitivity of the target and the metabolic pathway of the insecticide used to manage insect resistance. [ABSTRACT FROM AUTHOR]

Simple Summary: Planthopper outbreaks in rice are associated with excessive fertilizer applications. Public research has focused on developing resistant rice to combat these outbreaks. However, to preserve ecosystem resilience, natural enemy efficacy should be maintained on resistant and susceptible rice. We examined the impact of egg parasitoids on planthoppers (Nilaparvata lugens (Stål) [BPH] and Sogatella furcifera (Horváth) [WBPH]) and a leafhopper (Nephotettix virescens (Distant) [GLH]) in field plots of resistant (IR62) and susceptible (IR64) rice under low and high nitrogen. GLH and WBPH were more abundant in low-nitrogen plots during dry (GLH) and wet (GLH, WBPH) season sampling at an early crop stage. GLH were also more abundant on IR64. Parasitoids killed between 24 and 52% of planthopper eggs during exposures in trap plants. Parasitism by Oligosita and Anagrus wasps was higher on IR64 (BPH eggs) and in high-nitrogen plots (Oligosita spp. on BPH and WBPH eggs; Anagrus spp. on BPH eggs). Parasitism by Anagrus spp. was associated with the presence of honeydew and was highest where honeydew was derived from BPH feeding on IR62; these effects were only observed under high nitrogen. Results suggest that honeydew from IR62 favors parasitoids when plants are most vulnerable (i.e., under high nitrogen), thereby countering nitrogen-induced declines in host resistance. Host plant resistance is the most researched method for the management of planthoppers and leafhoppers in tropical rice. For optimal effects, resistance should be resilient to fertilizer inputs and work in synergy with natural enemies. In field plot experiments, we examined how rice resistance and fertilizer inputs affect mortality of planthopper and leafhopper eggs by hymenopteran parasitoids. We used IR62 as a variety with resistance to Nilaparvata lugens (Stål) [BPH], Sogatella furcifera (Horváth) [WBPH] and Nephotettix virescens (Distant) [GLH], and IR64 as a susceptible control. The herbivores were more abundant during wet season sampling in low-nitrogen plots. During this study, parasitoids killed between 31 and 38% of BPH eggs and 24 and 52% of WBPH eggs during four days of field exposure. Parasitism, mainly due to Oligosita spp., was generally higher in high-nitrogen and IR64 plots. Similar densities of eggs in exposed plants suggest that these trends were mediated by semiochemicals and therefore support the Optimal Defense Hypothesis. Honeydew from BPH on IR62 had more xylem-derived wastes than honeydew on IR64. We applied honeydew from both varieties to sentinel plants. Parasitism by Anagrus spp. was higher on plants of either variety treated with honeydew derived from IR62; however, the effect was only apparent in high-nitrogen plots. Results suggest that Anagrus spp., by responding to honeydew, will counter the nitrogen-induced enhancement of planthopper fitness on resistant rice. [ABSTRACT FROM AUTHOR]

In this study, we investigated the dynamic occurrence and vertical distribution of three types of rice planthoppers (Nilaparvata lugens, Sogatella furcifera, and Laodelphax striatellus) in Shanghai, China. Our results showed that S. furcifera and L. striatellus infested the lower part of rice plants in the early development stage, S. furcifera and L. striatellus inhabited every part of rice in the middle development stage, and L. striatellus and N. lugens formicated in the upper part of the rice plant in the posterior development stage. The populations of rice planthoppers were larger in July and September, Where more than 600 adult and nymphal planthoppers, per a hundred hills of rice, were found in late July, and out of the 600, the majority were the nymphs of S. furcifera and L. striatellus. S. furcifera was mainly found from July to October, L. striatellus during the rice development, and N. lugens after September, during which their maximal individual number, per a hundred hills of rice, was 480, 220, less than 50, respectively. In addition, our results showed that adult rice planthoppers were mostly observed from late August to mid‐October with the highest population being found during mid to late September. The adult S. furcifera, L. striatellus, and N. lugens were mostly observed in August and September, from August to October, and past mid‐September, respectively. Moreover, the number of adult L. striatellus that were sticking to yellow sticky card was significantly higher than that of S. furcifera and N. lugens. [ABSTRACT FROM AUTHOR]

A field experiment was conducted to evaluate the bio-efficacy and phytotoxicity of Thiocyclam hydrogen oxalate 3% + Clothianidin 1.2% GR against major paddy pests during Kharif, 2020 and Rabi, 2021. The treatments were: T1 - Thiocyclam hydrogen oxalate 3% + Clothianidin 1.2% GR @ 225+90 g a.i./ha; T2 - Thiocyclam hydrogen oxalate 3% + Clothianidin 1.2% GR @ 300+120 g a.i./ha; T3 - Thiocyclam hydrogen oxalate 3% + Clothianidin 1.2% GR @ 375+150 g a.i./ ha; T4 - Thiocyclam hydrogen oxalate 4% GR @ 500 g a.i./ha; T5 - Clothianidin 50% WDG @ 12 g a.i./ha and T6 - Clothianidin 50% WDG @ 125 g a.i./ha, T7 - Cartap hydrochloride 4% GR @ 1000 g a.i./ha and T8 -Untreated check. Results revealed that, all the treatments were effective in controlling stem borer damage, leaf folder damage, Brown planthopper and White backed plant hopper population and significant increase in yield but among the tested chemicals Thiocyclam hydrogen oxalate 3% + Clothianidin 1.2% GR @ 375+150 and 300+120 g a.i./ha showed highest control of pests at 20 days after treatment. The test compound was found to be relatively safe to natural enemies in the paddy ecosystem and also did not cause any kind of phytotoxicity [ABSTRACT FROM AUTHOR]

This study evaluates the field efficacy of some biopesticides i.e., azadirachtin 1%EC @ 250, 500 & 750 ml, Bacillus thuringiensis @1500, 2000 & 2500 g, Beauveria bassiana 10%SC @2000, 2250 & 2500 ml and chlorpyriphos 20EC @2500 ml (check)/ ha against the brown plant hopper Nilaparvata lugens (Stål) and white backed plant hopper, Sogatella furcifera (Horváth) in direct seeded rice. The experiment was carried out at the Punjab Agricultural University, Ludhiana and Punjab Agricultural University Regional Research Station, Gurdaspur during 2017-18. It was observed that all tested biopesticides were found significantly effective. Beauveria bassiana @2500 ml/ ha was the most effective, while the maximum costbenefit ratio was obtained with chlorpyriphos 20EC @2500 ml (standard check) followed by azadirachtin 1% EC @250 and 500 ml/ ha. Despite less cost benefits, biopesticides can be safer to environment. [ABSTRACT FROM AUTHOR]

Effect of certain insecticides in rice ecosystem was studied for their role in resurgence of brown plant hopper (BPH) during kharif and rabi 2016-17. Among fourteen insecticides evaluated, seven insecticides viz., chlorpyriphos, profenophos, deltamethrin, cypermethrin, bifenthrin, lambdacyhalothrin and imidacloprid were observed to significantly increase the incidence of BPH over untreated check after 1st, 2nd and 3rd sprays consistently and resulted in induced resurgence. Acephate, monocrotophos, cartap hydrochloride, fipronil, chlorantraniliprole, buprofezin and pymetrozine effectively controlled the BPH and did not induce resurgence. Thus, these can be used judiciously, with periodic monitoring of resistance and resurgence. [ABSTRACT FROM AUTHOR]

Wing polymorphism significantly contributes to the ecological success of some insect species. For example, the brown planthopper (BPH) Nilaparvata lugens, which is one of the most destructive rice pests in Asia, can develop into either highly mobile long‐winged or highly fecund short‐winged adult morphs. A recent study reported a highly provocative result that the Hox gene Ultrabithorax (Ubx) is expressed in BPH forewings and showed that this wing development gene is differentially expressed in nymphs that develop into long‐winged versus short‐winged morphs. Here, we found that Ubx may be a mir‐9a target, and used dual luciferase reporter assays and injected micro RNA (miRNA) mimics and inhibitors to confirm the interactions between mir‐9a and NlUbx. We measured the mir‐9a and NlUbx expression profiles in nymphs and found that the expression of these two biomolecules was negatively correlated. By rearing BPH nymphs on host rice plants with different nutritional status, we were able to characterize a regulatory cascade between insulin receptor genes, mir‐9a, and NlUbx that regulate wing length in BPHs. When host quality was low, NlInR1 expression in the nymph terga increased and NlInR2 expression decreased; this led to a higher mir‐9a level, which in turn reduced the NlUbx transcript level and ultimately resulted in longer wing lengths. Beyond extending our understanding of the interplay between host plant status and genetic events that modulate polymorphism, we demonstrated both the upstream signal and miRNA‐based regulatory mechanism that control Ubx expression in BPH forewings. [ABSTRACT FROM AUTHOR]

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Carboxylesterases (CarEs) represent one of the major detoxification enzyme families involved in insecticide resistance. However, the function of specific CarE genes in insecticide resistance is still unclear in the insect Nilaparvata lugens (Stål), a notorious rice crop pest in Asia. In this study, a total of 29 putative CarE genes in N. lugens were identified, and they were divided into seven clades; further, the β‐esterase clade was significantly expanded. Tissue‐specific expression analysis found that 17 CarE genes were abundantly distributed in the midgut and fat body, while 12 CarE genes were highly expressed in the head. The expression of most CarE genes was significantly induced in response to the challenge of nitenpyram, triflumezopyrim, chlorpyrifos, isoprocarb and etofenprox. Among these, the expression levels of NlCarE2, NlCarE4, NlCarE9, NlCarE17 and NlCarE24 were increased by each insecticide. Real‐time quantitative polymerase chain reaction and RNA interference assays revealed the NlCarE1 gene to be a candidate gene mainly involved in nitenpyram resistance, while simultaneously silencing NlCarE1 and NlCarE19 produced a stronger effect than silencing either one individually, suggesting a cooperative relationship in resistance formation. These findings lay the foundation for further clarification of insecticide resistance mediated by CarE in N. lugens. [ABSTRACT FROM AUTHOR]