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Feeding behavior of brown planthopper, Nilaparvata lugens (Stål) populations collected from different geographical regions Ludhiana, Nalgonda and West Godavari at three generations 1, 5 and 10 fed on rice plants grown under different CO2 and temperature levels 1) Ambient CO2@ 380±25ppm + ambient temperature (aCO2+aT), 2) Elevated CO2@500±25ppm + ambient temperature (eCO2+aT) and 3) Elevated CO2@500±25ppm + elevated temperature (eCO2+eT) in closed CO2 chambers was studied. Elevated CO2 + elevated temperature increased feeding rate of BPH nymphs while BPH adults showed declined feeding rate. BPH nymphal feeding rate increased with progressive generations while it decreased in BPH adults. Ludhiana adult BPH population showed higher honeydew excretion compared to West Godavari and Nalgonda populations. CO2 + temperature levels at progressive generations have varying effects on adults and nymphs of three BPH populations. Biochemical composition of rice plants grown under different CO2 levels revealed increased rate of soluble sugars, phenols and decreased rate of reducing sugars, soluble proteins, free amino acids, nitrogen, potassium, phosphorous in elevated CO2 + elevated temperature levels compared to ambient conditions. Increased feeding rate of BPH under elevated CO2 levels may be to compensate changes in host plant quality i.e., high soluble sugars and low nitrogen.

Buprofezin, a chitin synthesis inhibitor, is widely used to control several economically important insect crop pests. However, the overuse of buprofezin has led to the evolution of resistance and exposed off-target organisms present in agri-environments to this compound. As many as six different strains of bacteria isolated from these environments have been shown to degrade buprofezin. However, whether insects can acquire these buprofezin-degrading bacteria from soil and enhance their own resistance to buprofezin remains unknown. Here we show that field strains of the brown planthopper, Nilaparvata lugens, have acquired a symbiotic bacteria, occurring naturally in soil and water, that provides them with resistance to buprofezin. We isolated a symbiotic bacterium, Serratia marcescens (Bup_Serratia), from buprofezin-resistant N. lugens and showed it has the capacity to degrade buprofezin. Buprofezin-susceptible N. lugens inoculated with Bup_Serratia became resistant to buprofezin, while antibiotic-treated N. lugens became susceptible to this insecticide, confirming the important role of Bup_Serratia in resistance. Sequencing of the Bup_Serratia genome identified a suite of candidate genes involved in the degradation of buprofezin, that were upregulated upon exposure to buprofezin. Our findings demonstrate that S. marcescens, an opportunistic pathogen of humans, can metabolize the insecticide buprofezin and form a mutualistic relationship with N. lugens to enhance host resistance to buprofezin. These results provide new insight into the mechanisms underlying insecticide resistance and the interactions between bacteria, insects and insecticides in the environment. From an applied perspective they also have implications for the control of highly damaging crop pests. Author summary: The evolution of insect resistance to insecticides represents a major threat to the sustainable control of many of the world's most damaging crop pests. To effectively combat resistance it is important to understand the mechanisms underpinning resistance and their contribution to phenotype. Numerous studies have shown that resistance can result from mutations in the insect genome that alter the expression of detoxification enzymes or enhance their activity, or modify the affinity of the insecticide for the target receptor. However, emerging evidence suggests that symbiotic bacteria may also mediate insecticide resistance in host insects. In this study we show that a bacterium commonly found in the environment can be acquired by the economically important pest insect, Nilaparvata lugens, and confer resistance to the insecticide buprofezin. Using genomic and transcriptomic analyses we implicate a Rieske nonheme iron oxygenase (RHO) system and VOC family protein encoded in the Bup_Serratia genome in the degradation pathway of buprofezin. Our studies uncover a new mechanism of N. lugens resistance to buprofezin and illustrate the importance of considering microbe—host insect—environment interactions in the development of integrated pest management strategies. [ABSTRACT FROM AUTHOR]

Interactions between rice plants (Oryza sativa L.) and brown planthoppers (Nilaparvata lugens Stål, BPHs) are used as a model system to study the molecular mechanisms underlying plant-insect interactions. Small RNAs (sRNAs) regulate growth, development, immunity, and environmental responses in eukaryotic organisms, including plants and insects. Recent research suggests that sRNAs play significant roles in rice-BPH interactions by mediating post-transcriptional gene silencing. The focus of this review is to explore the roles of sRNAs in rice-BPH interactions and to highlight recent research progress in unraveling the mechanism of cross-kingdom RNA interference (ckRNAi) between host plants and insects and the application of ckRNAi in pest management of crops including rice. The research summarized here will aid in the development of safe and effective BPH control strategies. [ABSTRACT FROM AUTHOR]

Key message: OsSPL10 is a negative regulator of rice defense against BPH, knockout of OsSPL10 enhances BPH resistance through upregulation of defense-related genes and accumulation of secondary metabolites. Rice (Oryza sativa L.), one of the most important staple foods worldwide, is frequently attacked by various herbivores, including brown planthopper (BPH, Nilaparvata lugens). BPH is a typical monophagous, phloem-sucking herbivore that has been a substantial threat to rice production and global food security. Understanding the regulatory mechanism of defense responses to BPH is essential for improving BPH resistance in rice. In this study, a SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE 10 (OsSPL10) transcription factor was found to play a negative role in the defenses of rice against BPH. To gain insights into the molecular and biochemical mechanisms of OsSPL10, we performed combined analyses of transcriptome and metabolome, and revealed that knockout of OsSPL10 gene improved rice resistance against BPH by enhancing the direct and indirect defenses. Genes involved in plant hormone signal transduction, MAPK signaling pathway, phenylpropanoid biosynthesis, and plant–pathogen interaction pathway were significantly upregulated in spl10 mutant. Moreover, spl10 mutant exhibited increased accumulation of defense-related secondary metabolites in the phenylpropanoid and terpenoid pathways. Our findings reveal a novel role for OsSPL10 gene in regulating the rice defense responses, which can be used as a potential target for genetic improvement of BPH resistance in rice. [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]

In this paper, we formulate a population suppression model and a population replacement model with periodic impulsive releases of Nilaparvata lugens infected with wStri. The conditions for the stability of wild- $ N.\,lugens $ N. l u g e n s -eradication periodic solution of two systems are obtained by applying the Floquet theorem and comparison theorem. And the sufficient conditions for the persistence in the mean of wild $ N.\,lugens $ N. l u g e n s are also given. In addition, the sufficient conditions for the extinction and persistence of the wild $ N.\,lugens $ N. l u g e n s in the subsystem without wLug are also obtained. Finally, we give numerical analysis which shows that increasing the release amount or decreasing the release period are beneficial for controlling the wild $ N.\,lugens $ N. l u g e n s , and the efficiency of population replacement strategy in controlling wild populations is higher than that of population suppression strategy under the same release conditions. [ABSTRACT FROM AUTHOR]

The development of resistant rice (Oryza sativa L.) varieties is a key strategy for the eco-friendly control of brown planthopper (BPH: Nilaparvata lugens Stål). However, BPH outbreaks occur frequently owing to the evolution of virulent strains in the field and the rapid breakdown of monogenic resistance to BPH. Therefore, to enhance BPH resistance and gauge the effectiveness of gene pyramiding against strongly virulent BPH, we developed pyramided lines (PYLs) in the genetic background of 'IR64' carrying BPH resistance genes. We developed six IR64-PYLs (BPH3 + BPH17, BPH32 + BPH17, BPH32 + BPH20, BPH3 + BPH17-ptb, BPH20 + BPH3, and BPH17-ptb + BPH32) through marker-assisted selection. To assess the resistance of the IR64-PYLs, we conducted antibiosis test, honeydew test, and modified seedbox screening test (MSST) using strongly virulent BPH populations. The level of BPH resistance increased in all six IR64-PYLs compared to both 'IR64' and the corresponding NILs in MSST. Among them, IR64-BPH3 + BPH17 and IR64-BPH32 + BPH17 exhibited the highest resistance to BPH. However, the resistance level of most IR64-PYLs was not significantly higher than that of the corresponding NILs in antibiosis test. Thus, these PYLs could serve as a valuable resource for breeding programs aimed at improving resistance to virulent strains of BPH and enhancing their durability. [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]

BACKGROUND: The brown planthopper (Nilaparvata lugens, BPH) is the most destructive serious pest in rice production. Resistant varieties are effective means to defend against BPH, but the impact of the ingestion of resistant rice on BPH transcriptional regulation is still unclear. Here, we explore the molecular basis of the regulation by BPH feeding on resistant rice. RESULTS: BPH nymphs preferentially selected susceptible rice TN1 at 24 h after release in a choice test. Feeding on resistant rice IR56 under nonselective conditions increased mortality, decreased growth rate, and prolonged the molting time of BPH. Transcriptomic sequencing revealed 38 dysregulated genes, including 31 down‐regulated and seven up‐regulated genes in BPH feeding on resistant rice for 7 days compared with feeding on susceptible rice TN1. These genes were mainly involved in the pathways of growth and development, metabolism, energy synthesis, and transport. Finally, we showed that the toxicities of rice defensive compounds to BPH were dose‐dependent, and silencing of the BPH gene dehydrogenase/reductase SDR family member 11 (NlDHRS11) increased sensibility to the rice secondary compounds ferulic acid and resorcinol. CONCLUSION: The adaption of BPH feeding on resistant rice is orchestrated by dynamically regulating gene expressions, and NlDHRS11 is a gene involved in the detoxification of plant defensive chemicals. The current work provides new insights into the interaction between insects and plants, and will help to develop novel BPH control strategies. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The brown planthopper (BPH) Nilaparvata lugens (Stål) is a main pest on rice. It secretes saliva to regulate plant defense responses, when penetrating rice plant and sucking phloem sap through its stylet. However, the molecular mechanisms of BPH salivary proteins regulating plant defense responses remain poorly understood. A N. lugens DNAJ protein (NlDNAJB9) gene was highly expressed in salivary glands, and the knock down of NlDNAJB9 significantly enhanced honeydew excretion and fecundity of the BPH. NlDNAJB9 could induce plant cell death, and the overexpression of NlDNAJB9 gene in Nicotiana benthamiana induced calcium signaling, mitogen-activated protein kinase (MAPK) cascades, reactive oxygen species (ROS) accumulation, jasmonic acid (JA) hormone signaling and callose deposition. The results from different NlDNAJB9 deletion mutants indicated that the nuclear localization of NlDNAJB9 was not necessary to induce cell death. The DNAJ domain was the key region to induce cell death, and the overexpression of DNAJ domain in N. benthamiana significantly inhibited insect feeding and pathogenic infection. NlDNAJB9 might interact indirectly with NlHSC70-3 to regulate plant defense responses. NlDNAJB9 and its orthologs were highly conserved in three planthopper species, and could induce ROS burst and cell death in plants. Our study provides new insights into the molecular mechanisms of insect-plant interactions. [ABSTRACT FROM AUTHOR]

Agricultural landscapes are constantly changing as farmers adopt new production practices and respond to changing environmental conditions. Some of these changes alter landscape structure with impacts on natural pest control, pesticide use, and conservation of biodiversity. In rice agroecosystems the effect of landscape structure on natural enemies and pest suppression is often poorly understood. Here we investigate the effect of landscape composition and configuration on a key pest of rice, the brown planthopper (Nilaparvata lugens). Using N. lugens as sentinel prey coupled with predator exclusions, we investigated landscape effects on herbivore suppression and rice grain yield at multiple spatial scales in two regions of Bangladesh. Ladybird beetles and spiders were the most abundant natural enemies of N. lugens with landscape effects observed at all scales on ladybird beetles. Specifically, ladybird beetles were positively influenced by road edges, and fallow land, while spiders were strongly influenced only by rice phenology. Predator exclusion cages showed that N. lugens abundance significantly increased in caged plots, reducing rice gain yield. We also used an estimated biocontrol service index that showed a significant positive relationship with landscape diversity and a significant negative impact on pest density and yield loss. These results suggest that promoting fallow lands and fragmented patches between rice fields could lead to more sustainable insect pest management in rice agroecosystems, potentially reducing the practice of prophylactic insecticide use. [ABSTRACT FROM AUTHOR]

The Bph15 gene, known for its ability to confer resistance to the brown planthopper (BPH; Nilaparvata lugens Stål), has been extensively employed in rice breeding. However, the molecular mechanism by which Bph15 provides resistance against BPH in rice remains poorly understood. In this study, we reported that the transcription factor OsWRKY71 was highly responsive to BPH infestation and exhibited early-induced expression in Bph15-NIL (near-isogenic line) plants, and OsWRKY71 was localized in the nucleus of rice protoplasts. The knockout of OsWRKY71 in the Bph15-NIL background by CRISPR-Cas9 technology resulted in an impaired Bph15-mediated resistance against BPH. Transcriptome analysis revealed that the transcript profiles responsive to BPH differed between the wrky71 mutant and Bph15-NIL, and the knockout of OsWRKY71 altered the expression of defense genes. Subsequent quantitative RT-PCR analysis identified three genes, namely sesquiterpene synthase OsSTPS2, EXO70 family gene OsEXO70J1, and disease resistance gene RGA2, which might participate in BPH resistance conferred by OsWRKY71 in Bph15-NIL plants. Our investigation demonstrated the pivotal involvement of OsWRKY71 in Bph15-mediated resistance and provided new insights into the rice defense mechanisms against BPH. [ABSTRACT FROM AUTHOR]

As silicon is known to have a positive role in enhancing the resistance of rice plants to insects, an investigation on one aspect of the biochemical and molecular basis of rice plant defences mediated by silicon amendments against brown plant hopper Nilaparvata lugens (Stål), comprising field, pot culture and laboratory experiments was undertaken in OUAT. Two organic products; Diatomaceous Earth (DAE) at 0.15, 0.30 and 0.45 t/ha, and Rice Hull Ash (RHA) at 2, 3, 4 t/ha, along with one inorganic source, calcium silicate (CaSiO3) at 2, 3, 4 t/ha were soil applied as basal to evaluate their effects on the accumulation of silicon, proline, phenol, carbohydrates and protein in the plant tissues along with proteomic and Scanning Electron Microscope (SEM) studies. Results showed decreasing in proline and protein contents and increasing in silicon, phenol and carbohydrates contents in infected Si amended plants as compared to the control. Proteomic study showed appearing of a thick band of about 20 KDa in infested plants indicating its role in defense mechanism. Under SEM, the dumbbell shaped deposits of Si were marked clearly at different doses of silicon, indicating that the increase in silica dose enhanced its deposits, which was supported by EDAX-SEM data. Results of this study clearly demonstrated that soil amendments with silicon through organic and inorganic sources effectively caused biochemical and molecular changes that ultimately support the plant defenses against BPH. [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]

Brown planthopper Nilaparvata lugens , which can transmit rice ragged stunt virus, is a serious and damaging pest to rice plants. Rice plants can protect themselves from the associated diseases of N.lugens by either suppressing or replacing N.lugens by releasing N.lugens infected by a special strain of Wolbachia wStri. The long-distance migration habit of N.lugens is one of the important precursors leading up to the large-scale occurrence of N.lugens. To study the effect of migration on the transmission of Wolbachia in N.lugens , a Wolbachia spreading dynamics model with migration of N.lugens between two patches is put forward. The existence and local stability conditions of equilibrium points of the system and its subsystems are obtained. Moreover, the effects of migration on the dynamic properties and the control of N.lugens are analyzed; the results show that the system can exhibit a bistable phenomenon, and the migration can change the stability of equilibrium infected with wStri from stable to unstable. The quantitative control methods for the migration of the insect N.lugens are proposed, which provide a theoretical guidance for future field experiments. Lastly, we use the Markov chain Monte Carlo (MCMC) method to estimate the parameters of the wild N.lugens migration model based on limited observational data; the numerical simulation results show that migration can increase the quantity of N.lugens , which is consistent with the relevant experimental results. [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]

【Objective】To explore the resistance and genetic diversity of 76 common wild rice germplasm resources to brown planthopper in Guangxi, and to provide reference for the rational utilization of excellent resistant rice germplasm resources.【Method】The resistance to brown planthopper at seedling stage was identified in 76 common wild rice germplasm resources from 8 populations in Lingui, Guigang, Yongning, Bobai, Hengzhou, Fusui, Yulin and Fangchenggang. The genetic diversity of the tested materials was analyzed using 62 SSR primers and population genetic structure was analyzed using Structure ver 2.3.4, and cluster diagram was constructed. The genetic differentiation coefficient and gene flow among populations were analyzed by GenAlEx 6.5, and molecular variance analysis was performed for different populations.【Result】The results showed that 7 materials showed high resistance, 34 materials were resistant, 31 materials were moderately resistant, and 4 materials were moderately susceptible. In the genetic diversity analysis, 669 alleles were detected in the 76 materials, with an average of 10.79 alleles per locus, and the allelic variation ranged from 4 to 19, including 348 rare alleles, accounting for 52.02% of the total, with an average of 5.613 per locus; the main allele frequency variation ranged from 0.158 to 0.855, with an average of 0.373. Nei’s genetic diversity index (He) gene ranged from 0.260 to 0.894 with an average of 0.754, and the variation of polymorphic information content (PIC) ranged from 0.248 to 0.885 with an average of 0.727. He of the eight populations were: Fangchenggang ＞ Yongning ＞ Guigang ＞ Bobai ＞ Fusui ＞ Hengzhou ＞ Yulin ＞ Lingui, and resistance was not significantly correlated with population latitude and He (P＞0.05), and the correlation coefficient (r) between population latitude and population He was -0.822, reaching a significant level (P＜0.05). When K=3, the tested germplasms could be divided into 3 groups., similar to the results of cluster analysis; 85.71% of the eight populations showed moderate genetic differentiation between two populations; gene flow analysis showed frequent gene exchange between the populations of Fangchenggang, Bobai, Yongning, and between Guigang and Fusui. AMOVA analysis showed that the sources of genetic variation were mainly intra-individual and inter-individual, and the proportion of inter-group variation was small. 【Conclusion】Most of the materials in this study showed good resistance to brown planthopper and rich genetic diversity, and it is important to identify new resistance genes and excellent alleles, and transfer new resistance gene using modern molecular biology techniques to breed resistant rice varieties with multi-resistance and high-quality. [ABSTRACT FROM AUTHOR]

Brown planthopper, Nilaparvata lugens (Stål) is one of the most destructive pests of rice in Southeast Asia. It expresses a differential reaction to resistant rice cultivars and various insecticide groups in different geographic locations. Therefore, genetic diversity among N. lugens populations must be understood for their effective management. Hence, in the present study, the genetic structure and diversity of 22 N. lugens populations collected from 22 hotspot regions of India were analysed using with genomic simple sequence repeat (SSR) markers. Results revealed that the mean genetic diversity was 0.399 and polymorphic information content was 0.337 in the 30 selected SSR markers. Further, molecular variance revealed only a 2% variation among the populations and 98% within a population. In cluster and population structure analysis, all 22 populations were sub-grouped into three groups. Interestingly, the North and West Indian populations showed high genetic similarity and assembled into one cluster in cluster analysis. The East and South Indian populations were evenly segregated into the remaining two clusters. Similarly, the North and West Indian populations shared the same compartment in principal coordinate analysis. This variation might be associated with the N. lugens migration due to wind movement of the southwest monsoon in two branches, viz. Arabian Sea branch and Bay of Bengal branch. The present study provides molecular evidence for genetic variation among different populations of N. lugens in India. The information could be helpful to devise an efficient management strategy against this pest in different rice ecosystems. [ABSTRACT FROM AUTHOR]

Background: Pest management plays crucial role in yield prediction in all crops. In Rice, Brown Planthopper (BPH) plays major role in yield reduction. Pest forewarning in agriculture is the important tool and popularly used in various countries to avoid huge fertilizer and pesticide application. In this regard, Hyperspectral remote sensing gives various information about the spectral characteristics of BPH infected plants. Methods: Investigations were carried out to assess the damage of BPH infestation at the field level using a portable Hyper spectral radiometer. The farmers field at the BPH prone area of Kuttalam block, Nagapattinam district, Tamil Nadu was chosen to analyze the spectral reflectance of BPH -infected and uninfected plants and derive certain vegetation indices for accurate forewarning. The specific spectral bands from visible to infra-red (445 nm, 550 nm, 670 nm, 760 nm, 800 nm) were utilized to detect of BPH-infested plants over the field area. Result: Among various vegetation indices, the index MCARI (Modified Chlorophyll Absorption Reflectance Index) was performed well with high accuracy from early to late infestation at the field level and considered as the most effective tool in Precision Agriculture. As a result, The specific indices were analysed over BPH infected area to prevent greater spreading of pest damage and to minimize pesticides in the field. [ABSTRACT FROM AUTHOR]

Insects often face both conditions with sufficient nutrients and conditions of undernutrition in the field. Through gustatory receptors, insects sense nutrients and regulate their physiological functions such as feeding and reproduction. However, it remains unclear whether signaling pathways activated by gustatory receptors depend on the concentration of nutrients and whether the difference in signaling pathways directly affects insects' physiological functions. Herein, we found that a sugar gustatory receptor, NlGr11, from the brown planthopper (BPH), Nilaparvata lugens, activated G protein‐coupled signaling and ionotropic pathways when bound to high galactose concentration. BPHs subsequently demonstrated longer feeding times, feeding loads, and higher vitellogenin (NlVg) expression than BPHs exposed to high galactose concentrations, which only activated the ionotropic pathway. For the first time, our findings link plant nutrient conditions, signaling pathways activated by nutrients, and their gustatory receptors, and nutrient dose‐dependent feeding efficacy and vitellogenin (Vg) expression in an insect. This will help us to better understand the molecular mechanism for insect feeding strategies on plants at different stages of nutritional conditions. [ABSTRACT FROM AUTHOR]

The forkhead box O (FoxO) protein is the main transcriptional effector downstream of the insulin/insulin‐like signaling pathway and regulates many developmental and physiological processes. Holometabolous insects with loss‐of‐function mutations in FoxO exhibit phenotypes distinct from those of hemimetabolous insects in which RNA interference was used. Despite the functional importance of FoxO, whether hemimetabolous insects share an evolutionally conserved function of FoxO with holometabolous insects remains to be clarified. We used the clustered regularly interspaced short palindromic repeats/CRISPR‐associated 9 (CRISPR/Cas9) genome editing‐system to establish a homozygous FoxO‐null mutant (NlFoxO4E) of the wing‐dimorphic brown planthopper (BPH) Nilaparvata lugens, an economically important insect pest of rice fields. The phenotypes of NlFoxO4E mutants included extended nymphal duration, shortened lifespan, reduced reproduction, and decreased stress resistance. In addition, depletion of NlFoxO promoted cell proliferation in wing buds and led to 100% long‐winged morphs, in stark contrast to short‐winged wild‐type BPHs. These findings indicate that NlFoxO is highly functionally conserved with its counterpart in holometabolous insects, and is required for optimal fitness of N. lugens. The insights from FoxO studies may facilitate the identification of potential target genes for BPH control applications. [ABSTRACT FROM AUTHOR]

Brown planthopper (BPH) is the most problematic insect in rice cultivation, as it decreases crop yields. In this study, 143 upland rice varieties were genotyped for five essential Bph resistance genes: bph2, Bph3, Bph14, Bph15, and Bph17. The gene frequencies of the five Bph resistance genes varied from 33.57% to 61.54%. The 139 varieties contained one to five Bph resistance genes. Polymorphism information content values ranged from 0.4460 to 0.4984 with an average of 0.4744. Cluster analysis supported the subpopulations identified by STRUCTURE. An analysis of molecular variance analysis identified 7% variance among and 92% variance within subpopulations, indicating a significant gene exchange between the two subpopulations. The evaluation of BPH resistance using the SEM system by IRRI showed that 2 varieties were resistant to BPH, 29 varieties were moderately resistant, and 112 varieties were susceptible. The Bph3, Bph14, and Bph15 genes and BPH resistance showed significant correlation. These findings provide important information regarding BPH-resistant varieties for future use in rice breeding programs. [ABSTRACT FROM AUTHOR]

Herbivore‐induced plant defence responses share common components with plant responses to abiotic stresses. However, whether abiotic stress‐responsive factors influence the resistance of plants to herbivores by regulating these components remains largely unknown. Here, we cloned a dehydration‐responsive element‐binding gene in rice, OsDREB1A, and investigated its role in the resistance of rice to the phloem‐feeding herbivore, brown planthopper (BPH, Nilaparvata lugens), under normal and low temperatures. We found that OsDREB1A localized to the nucleus, and its transcripts in rice were up‐regulated in response to BPH infestation, low temperatures and treatment with methyl jasmonate or salicylic acid. Silencing OsDREB1A changed transcript levels of two defence‐related WRKY and two PLD genes, enhanced levels of jasmonic acid (JA), JA‐isoleucine and abscisic acid, and decreased the ethylene level in rice; these changes subsequently enhanced the resistance of plants to BPH, especially at 17°C, by decreasing the hatching rate and delaying the development of BPH eggs. Moreover, silencing OsDREB1A increased the growth of rice plants. These findings suggest that OsDREB1A, which positively regulates the resistance of rice to abiotic stresses, negatively regulates the resistance of rice to BPH. Summary statement: OsDREB1A, a positive modulator of rice tolerance to abiotic stress, negatively regulates the resistance of rice to BPH by influencing the biosynthesis of jasmonic acid (JA), JA‐isoleucine, abscisic acid, and ethylene. Brown planthopper appears able to use OsDREB1A to benefit itself by suppressing rice defences and resisting abiotic stresses. [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]

MicroRNAs (miRNAs) are small single‐stranded non‐coding RNAs involved in a variety of cellular events by regulating gene expression at the post‐transcriptional level. Several core genes in miRNA biogenesis have been reported to participate in a wide range of physiological events, in some insect species. However, the functional significance of miRNA pathway core genes in Nilaparvata lugens remains unknown. In the present study, we conducted a systematic characterisation of five core genes involved in miRNA biogenesis. We first performed spatiotemporal expression analysis and found that miRNA core genes exhibited similar expression patterns, with high expression levels in eggs and relatively high transcriptional levels in the ovaries and fat bodies of females. RNA interference experiments showed that injecting third‐instar nymphs with dsRNAs targeting the miRNA core genes, NlAgo1, NlDicer1, and NlDrosha resulted in high mortality rates and various degrees of body melanism, moulting defects, and wing deformities. Further investigations revealed that the suppression of miRNA core genes severely impaired ovarian development and oocyte maturation, resulting in significantly reduced fecundity and disruption of intercellular spaces between follicle cells. Moreover, the expression profiles of miR‐34‐5p, miR‐275‐3p, miR‐317‐3p, miR‐14, Let‐7‐1, and miR‐2a‐3p were significantly altered in response to the knockdown of miRNA core genes mixture, suggesting that they play essential roles in regulating miRNA‐mediated gene expression. Therefore, our results provide a solid theoretical basis for the miRNA pathway in N. lugens and suggest that the NlAgo1, NlDicer1, and NlDrosha‐dependent miRNA core genes are essential for the development and reproduction of this agricultural pest. [ABSTRACT FROM AUTHOR]

As a natural genetic reservoir, wild rice contains many favorable alleles and mutations conferring high yield and resistance to biotic and abiotic stresses. However, there are few reports describing favorable genes or QTL from the AA genome wild rice O. longistaminata, which is characterized by tall and robust habit and long tassels and anthers and shows high potential for use in cultivated rice improvement. We constructed a stable BC2F20 backcross inbred line (BIL) population of 152 lines from the cross of 9311 × O. longistaminat. Some BILs showed large panicles, large seeds, and strong resistance to rice false smut, bacterial leaf blight, rice blast spot, and brown planthopper. Genomic resequencing showed that the 152 BILs covered about 99.6% of the O. longistaminata genome. QTL mapping with 2432 bin markers revealed 13 QTL associated with seven yield traits and eight with resistance to brown planthopper and to four diseases. Of these QTL, 12 for grain yield and 11 for pest and disease resistance are novel in Oryza species. A large-panicle NIL1880 line containing QTL qPB8.1 showed a nearly 50% increase in spikelet number and 27.5% in grain yield compared to the recurrent parent 9311. These findings support the potential value of O. longistaminata for cultivated rice improvement. [ABSTRACT FROM AUTHOR]

The extensive pharmacological applications of the pyrazole-based compounds stimulated us to synthesize the highly functionalized, pyrazolylmalonyl diisothiocyanate derivative (2)via treating 2-((1,3-diphenyl-1H-pyrazol-4-yl)methylene)malonyl dichloride (1) with ammonium thiocyanate in acetonitrile at room temperature. The diisothiocyanate derivative 2 was subsequently conducted with a double molar ratio of different nitrogen nucleophiles like 4-acetylaniline, 2-aminobenzoic acid, 6-aminothiouracil, 2-aminothiadiazole derivative, hydrazine, phenylhydrazine, thiophene-2-carbohydrazide, 2-hydroxybenzohydrazide, 2-cyanoacetohydrazide, thiourea, thiosemicarbazide, 2-aminoaniline, and thiocarbohydrazide, aiming to construct some valuable heterocyclic systems. The synthesized compounds were screened for their insecticidal activity against healthy late third instar larvae P. interpunctella and Nilaparvata lugens and the results showed that pyrimidinethione, thiadiazolotriazine, and tetrazinethione derivatives exhibited the highest insecticidal potency that are supported by DFT stimulation and their molecular docking. [ABSTRACT FROM AUTHOR]

BACKGROUND: Light stimulation at a specific wavelength triggers various responses in insects and can be used for pest control. To develop efficient and ecofriendly photophysical pest control methods, the effects of green light on locomotion, growth (molting and eclosion) and reproduction in Nilaparvata lugens (Stål) (BPH), a major rice pest, were studied. Transcriptomics and transmission electron microscopy (TEM) were used to investigate the mechanisms involved. RESULTS: BPH adults showed disrupted daily locomotion patterns following green light treatment at night and exhibited abnormal locomotion peaks. Total 6‐day locomotion of brachypterous adults was significantly greater than in the control group. The durations of growth stages 1–4 were all shorter under green light treatment than in the control, whereas the time from fourth molting to eclosion (stage 5) was significantly longer. When BPH adults under green light treatment began laying eggs, the egg hatching ratio (36.69%) was significantly lower than in the control (47.49%). Moreover, in contrast to the control, BPH molting and eclosion events tended to happen more at night. Transcriptome analysis proved that green light significantly affected the expression of genes involved in cuticular proteins, chitin deacetylase and chitinase, which are related to cuticular development. TEM observations confirmed abnormal cuticular development in nymph and adult BPHs (endocuticle, exocuticle and pore canals) under green light treatment. CONCLUSION: Green light treatment at night notably affected locomotion, growth and reproduction in BPH, thus providing a novel idea for controlling this pest. © 2023 Society of Chemical Industry. [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 brown planthopper (Nilaparvata lugens) is the main migratory pest in many rice growing areas in Asia. E78 is a member of the nuclear hormone receptor superfamily which plays an important role in egg development and maternal regulation of early embryogenesis. In this study, brown planthopper E78 (NlE78) was cloned, and the predicted amino acid sequence showed that it contains two conserved domains: NR-LBD and DBD. qRT-PCR showed that the expression of NlE78 is high in the fifth instar nymphs and the ovaries of females. After downregulation of NlE78, the rate of moulting failure (33.2%) increased significantly, and ovarian development was delayed. However, when NlE78 was downregulated together with NlE93, the emergence rate increased significantly (78.79%), and ovarian development was similar to that when NlE78 was downregulated but not delayed. A co-immunoprecipitation experiment showed that NlE78 interacts with NlE93, a crucial downstream transcription factor of the ecdysone signalling pathway. Cellular localization by immunofluorescence revealed that NlE78 and NlE93 are expressed in the nucleus. This study indicates that NlE78 regulates ovarian development and moulting, possibly through its interaction with NlE93. This study is of great significance for the development of new pesticides and control methods based on newly discovered targets.

Death-associated protein-1 (DAP-1) plays a crucial role in cell growth, migration, autophagy, and apoptosis in mammals. However, its function in insects remains unclear. In the present study, we cloned and identified Nilaparvata lugens DAP-1 (NlDAP-1). NlDAP-1 was expressed during all developmental stages and in all tissues of N. lugens, being particularly higher in the ovaries of female adults. RNAi with double-stranded NlDAP-1 RNA significantly inhibited the expression of NlDAP-1, leading to premature death (dying seven days earlier), delayed ovarian development, and fewer offspring (76.7% reduction in eggs with 77.4% reduction in egg hatching rate). Additionally, an immunofluorescence experiment showed that NlDAP-1 was highly expressed when yeast-like symbionts (YLSs) entered N. lugens oocytes, and inhibiting the expression of NlDAP-1 disturbed the process; the RNAi of NlDAP-1 caused a 34.9% reduction in the YLSs that entered oocytes. These results indicate that NlDAP-1 plays a crucial role in the reproductive development of N. lugens and the transovarial transmission of its YLSs.

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.

In this paper, we formulate a population suppression model and a population replacement model with periodic impulsive releases of Nilaparvata lugens infected with wStri. The conditions for the stability of wild-[Formula: see text]-eradication periodic solution of two systems are obtained by applying the Floquet theorem and comparison theorem. And the sufficient conditions for the persistence in the mean of wild [Formula: see text] are also given. In addition, the sufficient conditions for the extinction and persistence of the wild [Formula: see text] in the subsystem without wLug are also obtained. Finally, we give numerical analysis which shows that increasing the release amount or decreasing the release period are beneficial for controlling the wild [Formula: see text], and the efficiency of population replacement strategy in controlling wild populations is higher than that of population suppression strategy under the same release conditions.

Glutamine:fructose-6-phosphate aminotransferases (GFATs) and phosphofructokinase (PFKs) are the principal rate-limiting enzymes involved in hexosamine biosynthesis pathway (HBP) and glycolysis pathway, respectively. In this study, the NlGFAT and NlPFK were knocked down through RNA interference (RNAi) in Nilaparvata lugens, the notorious brown planthopper (BPH), and the changes in energy metabolism were determined. Knockdown of either NlGFAT or NlPFK substantially reduced gene expression related to trehalose, glucose, and glycogen metabolism pathways. Moreover, trehalose content rose significantly at 72 h after dsGFAT injection, and glycogen content increased significantly at 48 h after injection. Glucose content remained unchanged throughout the experiment. Conversely, dsPFK injection did not significantly alter trehalose, but caused an extreme increase in glucose and glycogen content at 72 h after injection. The Knockdown of NlGFAT or NlPFK significantly downregulated the genes in the glycolytic pathway, as well as caused a considerable and significant decrease in pyruvate kinase (PK) activity after 48 h and 72 h of inhibition. After dsGFAT injection, most of genes in TCA cycle pathway were upregulated, but after dsNlPFK injection, they were downregulated. Correspondingly, ATP content substantially increased at 48 h after NlGFAT knockdown but decreased to an extreme extent by 72 h. In contrast, ATP content decreased significantly after NlPFK was knocked down and returned. The results have suggested the knockdown of either NlGFAT or NlPFK resulted in metabolism disorders in BPHs, highlighting the difference in the impact of those two enzyme genes on energy metabolism. Given their influence on BPHs energy metabolism, developing enzyme inhibitors or activators may provide a biological control for BPHs. [ABSTRACT FROM AUTHOR]

Biotic stress is one of the major threats to stable rice production. Climate change affects the shifting of pest outbreaks in time and space. Genetic improvement of biotic stress resistance in rice is a cost-effective and environment-friendly way to control diseases and pests compared to other methods such as chemical spraying. Fast deployment of the available and suitable genes/alleles in local elite varieties through marker-assisted selection (MAS) is crucial for stable high-yield rice production. In this review, we focused on consolidating all the available cloned genes/alleles conferring resistance against rice pathogens (virus, bacteria, and fungus) and insect pests, the corresponding donor materials, and the DNA markers linked to the identified genes. To date, 48 genes (independent loci) have been cloned for only major biotic stresses: seven genes for brown planthopper (BPH), 23 for blast, 13 for bacterial blight, and five for viruses. Physical locations of the 48 genes were graphically mapped on the 12 rice chromosomes so that breeders can easily find the locations of the target genes and distances among all the biotic stress resistance genes and any other target trait genes. For efficient use of the cloned genes, we collected all the publically available DNA markers (~500 markers) linked to the identified genes. In case of no available cloned genes yet for the other biotic stresses, we provided brief information such as donor germplasm, quantitative trait loci (QTLs), and the related papers. All the information described in this review can contribute to the fast genetic improvement of biotic stress resistance in rice for stable high-yield rice production. [ABSTRACT FROM AUTHOR]

BPH (brown planthopper) and WBPH (white backed planthopper) are significant rice pests that often co-occur as sympatric species and cause substantial yield loss. Despite their genetic similarities, different host-resistance genes confer resistance against these two hoppers. The defense mechanisms in rice against these pests are complex, and the molecular processes regulating their responses remain largely unknown. This study used specific recombinant inbred lines (RILs) derived from a cross between rice varieties RP2068-18-3-5 (BPH- and WBPH-resistant) and TN1 (BPH- and WBPH-susceptible) to investigate the mechanisms of interaction between these planthoppers and their rice hosts. WBPH and BPH were allowed to feed on specific RILs, and RNA-Seq was carried out on WBPH insects. Transcriptome profiling and qRT-PCR results revealed differential expression of genes involved in detoxification, digestion, transportation, cuticle formation, splicing, and RNA processing. A higher expression of sugar transporters was observed in both hoppers feeding on rice with resistance against either hopper. This is the first comparative analysis of gene expressions in these insects fed on genetically similar hosts but with differential resistance to BPH and WBPH. These results complement our earlier findings on the differential gene expression of the same RILs (BPH- or WBPH-infested) utilized in this study. Moreover, identifying insect genes and pathways responsible for countering host defense would augment our understanding of BPH and WBPH interaction with their rice hosts and enable us to develop lasting strategies to control these significant pests. [ABSTRACT FROM AUTHOR]

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 (Oryza sativa L.) is a staple food crop globally. Brown planthopper (Nilaparvata lugens Stål, BPH) is the most destructive insect that threatens rice production annually. More than 40 BPH resistance genes have been identified so far, which provide valuable gene resources for marker-assisted breeding against BPH. However, it is still urgent to evaluate rice germplasms and to explore more new wide-spectrum BPH resistance genes to combat newly occurring virulent BPH populations. To this end, 560 germplasm accessions were collected from the International Rice Research Institute (IRRI), and their resistance to current BPH population of China was examined. A total of 105 highly resistant materials were identified. Molecular screening of BPH resistance genes in these rice germplasms was conducted by developing specific functional molecular markers of eight cloned resistance genes. Twenty-three resistant germplasms were found to contain none of the 8 cloned BPH resistance genes. These accessions also exhibited a variety of resistance mechanisms as indicated by an improved insect weight gain (WG) method, suggesting the existence of new resistance genes. One new BPH resistance gene, Bph44(t), was identified in rice accession IRGC 15344 and preliminarily mapped to a 0–2 Mb region on chromosome 4. This study systematically sorted out the corresponding relationships between BPH resistance genes and germplasm resources using a functional molecular marker system. Newly explored resistant germplasms will provide valualble donors for the identification of new resistance genes and BPH resistance breeding programs. [ABSTRACT FROM AUTHOR]

The quinoline-acid hydrazide derivative was synthesized and transformed into a variety of interesting N-heterocycles like pyridazinone, oxadiazole, triazolopyridazine, and triazole derivatives. These N-heterocycles interacted with chitosan nanoparticles to produce different chitosan-heterocyclic nanocomposites. The nanocomposites obtained were characterized using Transmission electron microscopy, X-ray diffraction, and Fourier-transform infrared techniques and exhibited a somewhat narrow size distribution with an average particle size of 10-53 nm. The insecticidal activity for some of the synthesized N-heterocycles and their nanocomposites obtained were screened against Mythimna separata and Nilaparvata lugens. The obtained chitosan-N-heterocycles nanocomposites enhanced the insecticidal activity. [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]

BACKGROUND: Previous studies have shown that fungicides have insecticidal activity that can potentially be used as an insecticide resistance management strategy in the brown planthopper Nilaparvata lugens (Stål). However, the mechanism that induces mortality of N. lugens remains elusive. RESULTS: In the present study, the insecticidal activities of 14 fungicides against N. lugens were determined, of which tebuconazole had the highest insecticidal activity compared with the other fungicides. Furthermore, tebuconazole significantly inhibited the expression of the chitin synthase gene NlCHS1; the chitinase genes NlCht1, NlCht5, NlCht7, NlCht9, and NlCht10; and the β‐N‐acetylhexosaminidase genes NlHex3, NlHex4, NlHex5 and NlHex6; it significantly suppressed the expression of ecdysteroid biosynthetic genes as well, including SDR, CYP307A2, CYP307B1, CYP306A2, CYP302A1, CYP315A1 and CYP314A1 of N. lugens. Additionally, tebuconazole affected the diversity, structure, composition, and function of the symbiotic fungi of N. lugens, as well as the relative abundance of saprophytes and pathogens, suggesting that tebuconazole reshapes the diversity and function of symbiotic fungi of N. lugens. CONCLUSION: Our findings illustrate the insecticidal mechanism of tebuconazole, possibly by inhibiting normal molting or disrupting microbial homeostasis in N. lugens, and provide an important rationale for developing novel insect management strategies to delay escalating insecticide resistance. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Brown planthopper (Nilaparvata lugens Stål, BPH) is one of the most destructive pests of rice. Non-coding RNA plays an important regulatory role in various biological processes. However, comprehensive identification and characterization of long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) in BPH-infested rice have not been performed. Here, we performed a genome-wide analysis of lncRNAs and circRNAs in BPH6-transgenic (resistant, BPH6G) and Nipponbare (susceptible, NIP) rice plants before and after BPH feeding (early and late stage) via deep RNA-sequencing. A total of 310 lncRNAs and 129 circRNAs were found to be differentially expressed. To reveal the different responses of resistant and susceptible rice to BPH herbivory, the potential functions of these lncRNAs and circRNAs as competitive endogenous RNAs (ceRNAs) were predicted and investigated using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses. Dual-luciferase reporter assays revealed that miR1846c and miR530 were targeted by the lncRNAs XLOC_042442 and XLOC_028297, respectively. In responsive to BPH infestation, 39 lncRNAs and 21 circRNAs were predicted to combine with 133 common miRNAs and compete for miRNA binding sites with 834 mRNAs. These mRNAs predictably participated in cell wall organization or biogenesis, developmental growth, single-organism cellular process, and the response to stress. This study comprehensively identified and characterized lncRNAs and circRNAs, and integrated their potential ceRNA functions, to reveal the rice BPHresistance network. These results lay a foundation for further study on the functions of lncRNAs and circRNAs in the rice-BPH interaction, and enriched our understanding of the BPH-resistance response in rice. [ABSTRACT FROM AUTHOR]

Estimating population density is a fundamental study in ecology and crop pest management. The density estimation of small-scale animals, such as insects, is a challenging task due to the large quantity and low visibility. An herbivorous insect is the big enemy of crops, which often causes serious losses. Feeding of insects results in changes in physiology-related chemical compositions of crops, but it is unknown whether these changes can be used to estimate the population density of pests. The brown planthopper (BPH), Nilaparvata lugens, is a serious insect pest hiding under rice canopy to suck the sap of rice stems. BPH density is a crucial indicator for determining whether the control using pesticides will be carried out or not. Estimating BPH density is still dependent on manmade survey and light-trap methods, which are time-consuming and low-efficient. Here, we developed a new method based on the physiological traits of rice leaves. The feeding of BPHs significantly decreased the contents of chlorophyll (the SPAD readings), water, silicon, and soluble sugar in rice leaves. Four ratio physiological indices based on these four physiological traits of the BPH-damaged rice leaves to those of healthy leaves were established, and they were significantly correlated with BPH density in rice plants. A rice growth stage-independent linear model based on the four ratio physiological indices and adding the other two variables, BPH damage duration and population increase rate, was developed. This model exhibited a reasonable accuracy for estimating BPH density. This new method will promote the development of density estimation of pest populations toward nonprofessionalization and automation. [ABSTRACT FROM AUTHOR]

Although rice has many pests, brown planthopper (BPH) in particular is known to cause substantial damage. The pyramiding application of BPH-resistance genes BPH14 and BPH15 has proven effective in enhancing rice defense against BPH. However, the molecular mechanisms underlying BPH14/BPH15-conferred resistance remain unexplained. In this investigation, we analyzed the transcriptomes of near isogenic lines (NILs) containing either BPH14 (B14), BPH15 (B15), or BPH14/BPH15 (B1415), as well as their recurrent parent (RP) ‘Wushansimiao’. In total, we detected 14,492 differentially expressed genes (DEGs) across 12 mRNA profiles of resistant NILs and RP at different feeding stages. In the transcriptomic analysis, 531 DEGs appeared to be common among the resistant NILs compared to RP before and after BPH feeding. These common DEGs were enriched in defense response, phosphorylation, and salt stress response. In addition, 258 DEGs shared only in resistant NILs were obtained among the different feeding stages, which were enriched in oxidative stress response, karrikin response, and chloroplast organization. Considering the expression patterns and relevant research reports associated with these DEGs, 21 were chosen as BPH resistance candidates. In rice protoplasts, the candidate DEG OsPOX8.1 was confirmed to increase reactive oxygen species (ROS) accumulation by chemiluminescence measurement. Our results provide valuable information to further explore the defense mechanism of insectresistant gene pyramiding lines and develop robust strategies for insect control. [ABSTRACT FROM AUTHOR]