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Rapid climate change has diversified the dynamics of brown planthoppers, necessitating the development of rice cultivars with enhanced resistance. Brown planthoppers contribute to reduced grain yield and quality, and the rapid ecological changes caused by global warming are expected to exacerbate this damage. In Korea, rice cultivars resistant to brown planthoppers have primarily been bred using Bph1, bph2, and Bph18. Despite the known resistance of Bph3 to brown planthoppers, this gene is underutilized in rice breeding programs. Therefore, in this study, we aimed to analyze the association between brown planthopper resistant genes and rice agronomic traits by breeding segregated populations incorporating Bph3, Bph18, and BPH26. Segregated populations were derived from crosses between ‘Jeonju686’ (carrying Bph3 and BPH26) and ‘JJ621MR’ (carrying Bph18). Our analysis revealed that Bph18 was significantly associated with a reduced fertility rate. However, Bph3 did not significantly affect fertility-related traits. As Bph3 has been reported to confer strong resistance to brown planthoppers, it is expected to be actively utilized in future resistance breeding programs. Ultimately, maximizing the efficiency of molecular breeding techniques is expected to provide valuable insights into the development of rice cultivars with enhanced resistance to brown planthoppers. [ABSTRACT FROM AUTHOR]

Neuropeptide F (NPF) and short neuropeptide F (sNPF) are important neuropeptides and mainly affect feeding behaviour of insects. However, the regulation of insect feeding behaviour by NPF and sNPF appears to differ between species, and it is not clear how NPF and sNPF regulate the food intake of the brown planthopper (Nilaparvata lugens). Therefore, the functions of NPF and sNPF in regulating food intake and affecting the growth and antioxidant levels of N. lugens fed on host rice plants were investigated by knocking down NPF and sNPF respectively and simultaneously knocking down both of them by RNA interference. The results showed that NPF and sNPF were mainly expressed in the head of N. lugens, and N. lugens increased food intake after NPF and sNPF were knocked down, which was reflected in the prolonged duration of N4a and N4b waves in the electrical penetration graph (EPG) experiment after knocking down NPF and sNPF. In addition, knocking down NPF and sNPF led to the increase of body weight and mortality of N. lugens, and also led to the increase of antioxidant level of N. lugens. So it was concluded that NPF and sNPF could regulate food intake, maintain body weight stability and oxidative balance in N. lugens. Our study clarified the molecular mechanism of NPF and sNPF regulating feeding behaviour and affect the growth and antioxidant level of N. lugens. [ABSTRACT FROM AUTHOR]

The brown planthopper (BPH) is the most destructive insect pest in rice. Through a stylet, BPH secretes a plethora of salivary proteins into rice phloem cells as a crucial step of infestation. However, how various salivary proteins function in rice cells to promote insect infestation is poorly understood. Among them, one of the salivary proteins is predicted to be a carbonic anhydrase (Nilaparvata lugens carbonic anhydrase [NlCA]). The survival rate of the NlCA- RNA interference (RNAi) BPH insects was extremely low on rice, indicating a vital role of this salivary protein in BPH infestation. We generated NlCA transgenic rice plants and found that NlCA expressed in rice plants could restore the ability of NlCA- RNAi BPH to survive on rice. Next, we produced rice plants expressing the ratiometric pH sensor pHusion and found that NlCA- RNAi BPH induced rapid intracellular acidification of rice cells during feeding. Further analysis revealed that both NlCA- RNAi BPH feeding and artificial lowering of intracellular pH activated plant defense responses and that NlCA-mediated intracellular pH stabilization is linked to diminished defense responses, including reduced callose deposition at the phloem sieve plates and suppressed defense gene expression. Given the importance of pH homeostasis across the kingdoms of life, discovery of NlCA-mediated intracellular pH modulation uncovered a new dimension in the interaction between plants and piercing/sucking insect pests. The crucial role of NlCA for BPH infestation of rice suggests that NlCA is a promising target for chemical or trans-kingdom RNAi-based inactivation for BPH control strategies in plants. • Rapid intracellular acidification is a novel plant defense response • Brown planthopper (BPH) delivers carbonic anhydrase (NlCA) into rice for survival • NlCA counters intracellular acidification to suppress plant defense • pH-responsive regulators of defense responses are predicted to exist in the rice-BPH interaction The brown planthopper (BPH) is the most devastating insect pest in rice. Jiang et al. discover that BPH secretes a salivary carbonic anhydrase (NICA) to regulate the intracellular pH of the rice cell to facilitate its feeding and survival on rice plants and that NICA counters host intracellular pH acidification to diminished defense responses. [ABSTRACT FROM AUTHOR]

The rice brown planthopper (BPH), Nilaparvata lugens (Stål.), is a highly damaging insect pest to rice crops. The excessive use of synthetic chemicals has resulted in the development of resistance to insecticides and negative consequences for the environment and insect biodiversity. Hence, three common weed species, namely Ageratum conyzoides, Chromolaena odorata, and Mallotus paniculatus, were evaluated on the comparative extraction yield in different solvents, as well as the toxicity potential in the selected methanol extract. Further, the bioactive compounds in C. odorata were characterized, and potential bio-insecticide formulations were developed and evaluated on the BPH. Methanol extract displayed higher efficiency, yielding 17.29% compared to only 3.19% in hexane extract. Insecticidal activity evaluation demonstrated that C. odorata exhibited the highest toxicity (77.50% at 10,000 ppm), having a median lethal concentration (LC50) value of 977 ppm, while A. conyzoides (55.20% at 10,000 ppm) and M. paniculatus (60.0% at 12,000 ppm) produced LC50 values of 6,549 ppm and 21,940 ppm, respectively. Subsequently, a plant-based bio-insecticide was formulated using the crude methanol extract of C. odorata as the active ingredient. A mixture of surfactant (Emersense® AM 8025), oil (palm kernel oil ester), and water resulted in a stable macroemulsion called Emersense® AM 8025/palm kernel oil ester/water (EM-PKOE). The formulated macroemulsion displayed enhanced toxicity and efficacy against BPH nymphs, with an LC50 value of 220 ppm, outperforming the unformulated crude methanol extract (977 ppm). Chemical composition analysis using gas chromatography-mass spectrometry revealed that C. odorata primarily contained sesquiterpenes (24.14%). This study proposes C. odorata as a potential bio-insecticide for BPH combatants, necessitating further research on the formulation for eventual commercialization to sustainable BPH control in rice cultivation. [ABSTRACT FROM AUTHOR]

Simple Summary: The brown planthopper is a major pest threatening rice crops in Asia, making it essential to identify target genes for RNAi-based pest control strategies. The Cleavage Stimulation Factor (CstF) complex, which plays a key role in mRNA 3′ end processing, is composed of several critical genes, and mutations in these genes can cause severe developmental defects, indicating their potential as targets. In this study, we identified homologs of the human CstF complex genes (NlCstF50, NlCstF64, and NlCstF77) in Nilaparvata lugens and investigated their functions using RNAi techniques. These genes are expressed throughout all developmental stages and various tissues, with particularly high levels in eggs and testes. Targeting these genes with RNAi resulted in significant mortality, decreased egg production, and lower hatch rates. These results suggest that NlCstF50, NlCstF64, and NlCstF77 could be effective targets for RNAi-based pest control strategies. The Cleavage Stimulation Factor (CstF) complex, consisting of three subunits, is essential for the 3′ end processing of precursor messenger RNA (pre-mRNA). In mammals, this complex includes CstF50, CstF64, and CstF77, named according to their molecular weights, and these proteins are conserved across many organisms. However, the functional roles of the three CstF genes (NlCstF50, NlCstF64, and NlCstF77) in Nilaparvata lugens, a major rice pest, have not been fully explored. This study identified and characterized the sequences of these genes, with proteins encoded by NlCstF50, NlCstF64, and NlCstF77 consisting of 439, 419, and 732 amino acids, respectively. These proteins are conserved among various insect species. Spatio-temporal expression analysis revealed that these genes are expressed at all developmental stages and in various tissues, with peak levels in eggs and testes. RNA interference (RNAi) targeting one or all three NlCstF genes resulted in a reduction in gene expression by 68% to 90% at 72 h post-injection, indicating that multi-gene dsRNA can achieve similar silencing outcomes as single-gene dsRNA. Knocking down one or all three NlCstF genes caused significant lethal phenotypes and molting disruptions. Mortality rates increased from 62.5% (dsNlCstF50) to 95.4% (dsNlCstF(50+64+77)). Additionally, silencing these genes reduced the number of eggs laid per female and hatch rates. These results highlight the critical role of NlCstF genes in the development and reproduction of N. lugens, suggesting their potential as targets for RNAi-based pest control strategies. [ABSTRACT FROM AUTHOR]

Rice is a major global staple crop, but rising temperatures and freshwater shortages have made drought one of the most severe abiotic stresses affecting agriculture. Additionally, rice blast disease and brown planthopper infestations significantly impact yields. Therefore, developing water-saving, drought-resistant, high-yielding, and disease-resistant rice varieties is critical for sustainable rice production. The new water-saving and drought-resistant (WDR) rice 'Huhan 1516', bred using marker-assisted selection (MAS) and marker-assisted backcrossing (MABC) techniques, addresses these challenges. This variety is highly adaptable to drought-prone and water-scarce regions such as the Yangtze and Huai River basins. With its high yield, drought tolerance, and broad-spectrum resistance to rice blast (conferred by the Pi2 gene) and brown planthopper (BPH), 'Huhan 1516' is suitable for various farming systems and environments. Field trials show that this variety outperforms control varieties by 2.2% in yield and exhibits moderate resistance to both rice blast and brown planthopper. 'Huhan 1516' has been recognized as a new water-saving and drought-resistant rice variety by the state, and as a released cultivar, it has great potential for market promotion and application. [ABSTRACT FROM AUTHOR]

The brown planthopper (Nilaparvata lugens, BPH) is a serious insect pest responsible for causing immense economic losses to rice growers around the globe. The development of high-throughput sequencing technologies has significantly improved the research on this pest, and its genome structure, gene expression profiles, and host–plant interactions are being unveiled. The integration of genomic sequencing, transcriptomics, proteomics, and metabolomics has greatly increased our understanding of the biological characteristics of planthoppers, which will benefit the identification of resistant rice varieties and strategies for their control. Strategies like more optimal genome assembly and single-cell RNA-seq help to update our knowledge of gene control structure and cell type-specific usage, shedding light on how planthoppers adjust as well. However, to date, a comprehensive genome-wide investigation of the genetic interactions and population dynamics of BPHs has yet to be exhaustively performed using these next-generation omics technologies. This review summarizes the recent advances and new perspectives regarding the use of omics data for the BPH, with specific emphasis on the integration of both fields to help develop more sustainable pest management strategies. These findings, in combination with those of post-transcriptional and translational modifications involving non-coding RNAs as well as epigenetic variations, further detail intricate host–brown planthopper interaction dynamics, especially regarding resistant rice varieties. Finally, the symbiogenesis of the symbiotic microbial community in a planthopper can be characterized through metagenomic approaches, and its importance in enhancing virulence traits would offer novel opportunities for plant protection by manipulating host–microbe interactions. The concerted diverse omics approaches collectively identified the holistic and complex mechanisms of virulence variation in BPHs, which enables efficient deployment into rice resistance breeding as well as sustainable pest management. [ABSTRACT FROM AUTHOR]

Simple Summary: Carbamate insecticides like fenobucarb have been used in the Republic of Korea since 1981 to control brown planthopper (BPH). However, their excessive use has resulted in increased resistance in BPH Nilaparvata lugens. Therefore, in our current study, we aimed to investigate the main cause of higher resistance to fenobucarb in BPH19 compared to BPH80 and BPH15. We examined mutations in the acetylcholinesterase 1 gene, the target gene of carbamate, but did not find any previously reported mutations. However, through RNA-seq analysis, we discovered a strong correlation between the level of resistance development and the expression of the N. lugens carboxylesterase 1, Nl-EST1 gene in BPH19 compared to BPH80 and BPH15. This suggests that Nl-EST1 could be utilized as an expression marker for diagnosing resistance and integrated resistance management of N. lugens. Carbamate insecticides have been used for over four decades to control brown planthopper, Nilaparvata lugens, but resistance has been reported in many countries, including the Republic of Korea. The bioassay results on resistance to fenobucarb showed that the LC50 values were 3.08 for the susceptible strain, 10.06 for the 2015 strain, and 73.98 mg/L for the 2019 strain. Compared to the susceptible strain, the 2015 and 2019 strains exhibited resistance levels 3.27 and 24.02 times higher, respectively. To elucidate the reason for the varying levels of resistance to fenobucarb in these strains, mutations in the acetylcholinesterase 1 (ACE1) gene, the target gene of carbamate, were investigated, but no previously reported mutations were confirmed. Through RNA-seq analysis focusing on the expression of detoxification enzyme genes as an alternative resistance mechanism, it was found that the carboxylesterase gene Nl-EST1 was overexpressed 2.4 times in the 2015 strain and 4.7 times in the 2019 strain compared to the susceptible strain. This indicates a strong correlation between the level of resistance development in each strain and the expression level of Nl-EST1. Previously, Nl-EST1 was reported in an organophosphorus insecticide-resistant strain of Sri Lanka 2000. Thus, Nl-EST1 is crucial for developing resistance to organophosphorus and carbamate insecticides. Resistance-related genes such as Nl-EST1 could serve as expression markers for resistance diagnosis, and can apply to integrated resistance management of N. lugens. [ABSTRACT FROM AUTHOR]

BACKGROUND: N6‐Methyladenosine (m6A) is a common messenger RNA (mRNA) modification that affects various physiological processes in stress responses. However, the role of m6A modifications in plants responses to herbivore stress remains unclear. RESULTS: Here, we found that an infestation of brown planthopper (Nilaparvata lugens) female adults enhanced the resistance of rice to N. lugens. The m6A methylome analysis of N. lugens‐infested and uninfested rice samples was performed to explore the interaction between rice and N. lugens. The m6A methylation mainly occurred in genes that were actively expressed in rice following N. lugens infestation, while an analysis of the whole‐genomic mRNA distribution of m6A showed that N. lugens infestation caused an overall decrease in the number of m6A methylation sites across the chromosomes. The m6A methylation of genes involved in the m6A modification machinery and several defense‐related phytohormones (jasmonic acid and salicylic acid) pathways was increased in N. lugens‐infested rice compared to that in uninfested rice. In contrast, m6A modification levels of growth‐related phytohormone (auxin and gibberellin) biosynthesis‐related genes were significantly attenuated during N. lugens infestation, accompanied by the down‐regulated expression of these transcripts, indicating that rice growth was restricted during N. lugens attack to rapidly optimize resource allocation for plant defense. Integrative analysis of the differential patterns of m6A methylation and the corresponding transcripts showed a positive correlation between m6A methylation and transcriptional regulation. CONCLUSION: The m6A modification is an important strategy for regulating the expression of genes involved in rice defense and growth during rice–N. lugens interactions. These findings provide new ideas for formulating strategies to control herbivorous pests. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Background: The endocycle can generate cells referred to as 'polyploid'. Fizzy‐related protein (Fzr) plays an important role in driving the mitosis‐to‐endocycle transition. The brown planthopper (BPH), Nilaparvata lugens (Stål), a serious insect pest, feeds exclusively on rice. However, polyploidy and its regulatory mechanisms are poorly understood in BPH. Results: Here, we found that the ploidy levels of follicles H (FH) and accessory gland (AG) significantly increased with BPH age when examining the polyploidy of FH and AG of salivary glands. Fzr was identified as an important regulator for polyploidy in BPH salivary gland. Knockdown of Fzr resulted in a decrease in cell size and DNA content in nymph salivary glands. Fzr knockdown transcriptionally upregulated cyclin‐dependent kinase 1 (CDK1), CDK2, cyclin A (CycA) and CycB, and downregulated CycD, CycE, Myc and mini‐chromosome maintenance protein 2‐7 (MCM2‐7). Phenotypically, Fzr knockdown significantly suppressed salivary protein production, feeding and survival in BPH nymphs. Conclusion: Our results show that BPH salivary glands exhibit obvious polyploidy, and Fzr positively regulates the endocycle in nymph salivary gland. These findings provide clues for the study of the regulatory mechanisms of insect polyploidy. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Abstract The brown planthopper (BPH) is one of the most problematic pests affecting rice (Oryza sativa L.) yields in Asia. Breeding rice varieties containing resistance genes is the most economical and effective means of controlling BPH. In this study, the key factors in resistance to BPH were investigated between the high-resistance rice variety “R26” and the susceptible variety “TN1” using RNA-sequencing. We identified 9527 differentially expressed genes (DEGs) between the rice varieties under BPH-induced stress. Weighted time-course gene co-expression network analysis (WGCNA) indicated that the increased expression of genes is associated with plant hormones, MAPK signaling pathway and biosynthesis of other secondary metabolites, which were involved in disease resistance. A connection network identified a hub gene, OsREM4.1 (BGIOSGA024059), that may affect rice resistance to the BPH. Knocking out OsREM4.1 in rice can lead to a decrease in callose, making it less resistant to BPH. Overall, the expression of differentially expressed genes varies among rice varieties with different resistance in BPH invasion. Inaddition, R26 enhances resistance to BPH by upregulating genes and secondary metabolites related to stress resistance and plant immunity. In summary, our study provides valuable insights into the genome-wide expression profile of DEGs in rice under BPH invasion through high-throughput sequencing, and further suggests that R26 can be used to develop high resistance rice lines in BPH resistant breeding programs.

The brown planthopper (BPH) is one of the most problematic pests affecting rice (Oryza sativa L.) yields in Asia. Breeding rice varieties containing resistance genes is the most economical and effective means of controlling BPH. In this study, the key factors in resistance to BPH were investigated between the high-resistance rice variety "R26" and the susceptible variety "TN1" using RNA-sequencing. We identified 9527 differentially expressed genes (DEGs) between the rice varieties under BPH-induced stress. Weighted time-course gene co-expression network analysis (WGCNA) indicated that the increased expression of genes is associated with plant hormones, MAPK signaling pathway and biosynthesis of other secondary metabolites, which were involved in disease resistance. A connection network identified a hub gene, OsREM4.1 (BGIOSGA024059), that may affect rice resistance to the BPH. Knocking out OsREM4.1 in rice can lead to a decrease in callose, making it less resistant to BPH. Overall, the expression of differentially expressed genes varies among rice varieties with different resistance in BPH invasion. Inaddition, R26 enhances resistance to BPH by upregulating genes and secondary metabolites related to stress resistance and plant immunity. In summary, our study provides valuable insights into the genome-wide expression profile of DEGs in rice under BPH invasion through high-throughput sequencing, and further suggests that R26 can be used to develop high resistance rice lines in BPH resistant breeding programs. [ABSTRACT FROM AUTHOR]

Summary Terpene synthases (TPSs) are key enzymes in terpenoids synthesis of plants and play crucial roles in regulating plant defence against pests and diseases. Here, we report the functional characterization of OsTPS19 and OsTPS20, which were upregulated by the attack of brown planthopper (BPH). BPH female adults performed concentration‐dependent behavioural responses to (S)‐limonene showing preference behaviour at low concentrations and avoidance behaviour at high concentrations. Overexpression lines of OsTPS19 and OsTPS20, which emitted higher amounts of the monoterpene (S)‐limonene, decreased the hatching rate of BPH eggs, reduced the lesion length of sheath blight caused by Rhizoctonia solani and bacterial blight caused by Xanthomonas oryzae. While knockout lines of OsTPS19 and OsTPS20, which emitted lower amounts of (S)‐limonene, were more susceptible to these pathogens. Overexpression of OsTPS19 and OsTPS20 in rice plants had adverse effects on the incidence of BPH, rice blast, and sheath blight in the field and had no significant impacts on rice yield traits. OsTPS19 and OsTPS20 were found to be involved in fine‐tuning the emission of (S)‐limonene in rice plants and play an important role in defence against both BPH and rice pathogens. [ABSTRACT FROM AUTHOR]

Simple Summary: Rice breeding programs have included traditional varieties and wild rice species as sources of resistance to planthoppers and leafhoppers, which are major insect pests of rice in Asia. However, herbivores can adapt to resistance (known as virulence adaptation), sometimes in as little as 2 years. Virulence adaptation is a major obstacle for deploying resistant varieties. This review assesses knowledge of the rates, consequences, and mechanisms of virulence adaptation and on possible strategies to delay adaptation in rice landscapes. The review indicates that virulence is a complex of responses to minor and major resistance factors. Of particular interest are adaptations to major rice resistance genes that are likely governed by corresponding herbivore virulence genes. Evidence suggests that pre-adapted individuals (called forerunners) with these virulence genes occur in planthopper populations at relatively low frequencies but can rapidly build up numbers in response to planted resistant rice. However, gradual shifts in virulence may also occur due to intra- and intergenerational improvements in the herbivores' abilities to detoxify plant defense toxins, or to confound defense response networks. These may involve gradual changes in the expression of genes involved in successful herbivore attacks and may be associated with the herbivores or their endosymbionts. Several research gaps remain. In particular, there is a need for increased attention to practical, ecologically based deployment strategies that delay adaptation. In recent decades, research on developing and deploying resistant rice has accelerated due to the availability of modern molecular tools and, in particular, advances in marker-assisted selection. However, progress in understanding virulence adaptation has been relatively slow. This review tracks patterns in virulence adaptation to resistance genes (particularly Bph1, bph2, Bph3, and bph4) and examines the nature of virulence based on selection experiments, responses by virulent populations to differential rice varieties (i.e., varieties with different resistance genes), and breeding experiments that interpret the genetic mechanisms underlying adaptation. The review proposes that varietal resistance is best regarded as a combination of minor and major resistance traits against which planthoppers develop partial or complete virulence through heritable improvements that are reversable or through evolutionary adaptation, respectively. Agronomic practices, deployment patterns, and herbivore population pressures determine the rates of adaptation, and there is growing evidence that pesticide detoxification mechanisms can accelerate virulence adaptation. Research to delay adaptation has mainly focused on gene pyramiding (i.e., including ≥ two major genes in a variety) and multilines (i.e., including ≥ two resistant varieties in a field or landscape); however, these strategies have not been adequately tested and, if not managed properly, could inadvertently accelerate adaptation compared to sequential deployment. Several research gaps remain and considerable improvements in research methods are required to better understand and manage virulence adaptation. [ABSTRACT FROM AUTHOR]

Rice production is drastically affected by biotic stresses, namely, bacterial leaf blight (BB), blast (BL) and brown planthopper (BPH). As marker-assisted selection for uniplex gene screening in breeding population is often tedious, time-consuming and expensive, multiplex PCR is practically a reasonable choice for the testing of genes in the pyramided lines as it offers significant time- and cost-saving advantages. Therefore, a cost-effective multiplex PCR-based screening for simultaneous detection of three BB (Xa21, xa13, and Xa4), two BL (Pi1and Pi54) and two BPH resistance genes (Bph20 and Bph21) has been developed. This multiplex system can detect different combinations of BB, BL and BPH resistance. In addition to this most cost-effective method, a five-gene (Xa21, xa13, Pi54, Bph20 and Bph21) multiplex assay in a single PCR tube for three biotic stresses, BB, BL and BPH, has been developed. These standardized multiplex assays have been incorporated into our breeding programs for accelerated results. These assays have displayed no deviation and are in perfect correlation with the individual marker screenings. As one of the most efficient and cost-saving technologies, this technology will have a great impact in the seed industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Piriformospora indica is an endophytic fungus that can promote the growth and confer resistance against diverse stresses in host plants by root colonization. However, the effects of P. indica colonization on improving plant resistance to insect pests are still less explored. The brown planthopper (BPH) Nilaparvata lugens is a serious monophagous pest that causes extensive damage to rice plants. Here, we aimed to evaluate the effects of P. indica colonization on rice resistance against BPH. RESULTS: The colonization of P. indica in rice roots resisted damage from BPH. Age‐stage, two‐sex life table analyses showed that feeding on P. indica‐colonized rice plants affected BPH's female adult longevity, oviposition period, fecundity, population parameters and population size. BPH female adults feeding on P. indica‐colonized plants excreted less honeydew. P. indica colonization remarkably increased the duration of np, N2, and N3 waveform, as well as the occurrences of N1 and N2, and decreased the duration of N4‐b for BPH on rice plants. Meanwhile, the weight of BPH on the colonized plants was significantly lower than the control. In addition, the feeding and oviposition preferences of BPH to P. indica‐colonized plants were reduced. qRT‐RCR analyses revealed that P. indica colonization induced the expressions of jasmonic acid (JA)‐ and salicylic acid (SA)‐related genes in rice plants. CONCLUSION: P. indica colonization can reduce BPH performance on rice plants with potential inhibitory effects on population growth. Collectively, these results support the potential for endophytically colonized P. indica as an effective strategy to improve insect resistance of crops. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The brown planthopper (BPH), Nilaparvata lugens (Stål.), poses a significant threat to rice cultivation, acting as a key pest. The emergence of resistance to various insecticide classes has emerged as a prominent challenge, significantly hindering the effective management of N. lugens. Triflumezopyrim, a novel mesoionic chemistry insecticide, has recently been introduced in India for controlling N. lugens. Establishing the baseline susceptibility and monitoring its effectiveness throughout the life cycle of the molecule are crucial aspects for a newly commercialized insecticide like triflumezopyrim. In this study, the baseline toxicity of triflumezopyrim against brown planthopper populations from nine hotspot locations in three southern states of India was evaluated using the rice seedling dip method. The LC50 values varied between 0.123 and 0.268 mg/L, showing a 2.18-fold variation. This information holds significance in monitoring potential changes in N. lugens susceptibility to triflumezopyrim in the future, thereby assisting in the formulation of effective management strategies. [ABSTRACT FROM AUTHOR]

Simple Summary: Hybrid rice is grown by millions of Asian farmers and has normally higher yields compared to inbred varieties. However, hybrid rice has been associated with high damage from herbivores. This susceptibility could be due to the physiology of the hybrid plant type or due to a limited availability of male sterile parents that are necessary for hybrid seed production. We examined how plant type and breeding affect the relative susceptibilities of hybrid and inbred rice by exposing 32 rice genotypes to the brown planthopper, whitebacked planthopper, and yellow stemborer in controlled environments and field plots. We compared insect fitness on the plants and related this to the type and genetic similarity of genotypes. Despite their diverse origins (China, Colombia, India, and the Philippines), the hybrids and inbreds formed two distinct genetic groups, thereby confounding plant type and phylogeny. Hybrids were generally more susceptible to stemborers but not to planthoppers. Relative herbivore fitness was strongly influenced by plant origin (i.e., breeding program) with one group of related genotypes being relatively susceptible to all three herbivores. Our results indicate that hybrids are not inherently more susceptible than inbreds to insect herbivores and that careful screening with the elimination of the most susceptible genotypes is necessary to reduce herbivore damage to hybrid and inbred rice in Asia. Several studies have reported higher damage from insect herbivores to hybrid compared to inbred (pure line) rice. We used a collection of 20 hybrid and 12 inbred genotypes from diverse origins to test the hypotheses that hybrid rice susceptibility is due to (a) the hybrid plant type and/or (b) rice phylogeny. We challenged the genotypes with Nilaparvata lugans (BPH), Sogatella furcifera (WBPH) and Scirpophaga incertulas (YSB) in greenhouse and screenhouse bioassays and monitored herbivores in field plots. We used single nucleotide polymorphic (SNP) markers to assess genetic similarities between the genotypes and found that the hybrids and inbreds formed two distinct clusters regardless of origin. In the screenhouse, hybrids were more susceptible than inbreds to YSB; however, resistant hybrids and susceptible inbreds were also apparent from both the screenhouse and field plots. Plant biomass was the best predictor of susceptibility to YSB. Plant origin had a greater effect than plant type on susceptibility to BPH and WBPH. WBPH was the most abundant planthopper in the field plots where numbers were highly correlated with planthopper fitness in the greenhouse bioassays. Our results provide evidence that high-yielding hybrids that are relatively resistant to herbivores can be achieved through careful breeding. The avoidance of susceptible genotypes during breeding should remain a key element of integrated rice pest management. [ABSTRACT FROM AUTHOR]

Abstract The biogeographical range shift of insect pests is primarily governed by temperature. However, the range shift of seasonal long-distance migratory insects may be very different from that of sedentary insects. Nilaparvata lugens (BPH), a serious rice pest, can only overwinter in tropical-to-subtropical regions, and some populations migrate seasonally to temperate zones with the aid of low-level jet stream air currents. This study utilized the CLIMEX model to project the overwintering area under the climate change scenarios of RCP2.6 and RCP8.5, both in 2030s and 2080s. The overwintering boundary is predicted to expand poleward and new overwintering areas are predicted in the mid-latitude regions of central-to-eastern China and mid-to-southern Australia. With climate change, the habitable areas remained similar, but suitability decreased substantially, especially in the near-equatorial regions, owing to increasing heat stress. The range shift is similar between RCP2.6-2030s, RCP2.6-2080s, and RCP8.5-2030s, but extreme changes are projected under RCP8.5-2080s with marginal areas increasing from 27.2 to 38.8% and very favorable areas dropping from 27.5 to 3.6% compared to the current climate. These findings indicate that climate change will drive range shifts in BPH and alter regional risks differently. Therefore, international monitoring programs are needed to effectively manage these emerging challenges.

Conventional breeding approaches often rely on bi-parental crosses, in which analysis occurs only on two alleles, and genetic recombination in such a population is insufficient, limiting genetic diversity. Multi-parent advanced generation inter-cross (MAGIC) populations display large sets of recombinant inbred lines (RILs) that exhibit a genetic mosaic of multiple founder parents. MAGIC populations result in a broader genetic base that has emerged as a powerful tool for genetic analysis and breeding for disease resistance in rice. This study developed the MAGIC population by intermating eight diverse founder parents. Conducting the molecular survey sought to analyze the genes resistant to bacterial blight (BB) and brown planthopper (BPH). The research used primers specific for Xa21, xa13, Xa4, and Bph1 in the polymerase chain reaction (PCR). The survey identified combinations of three genes: (Xa4+xa13+Xa21) in BR52 and (Xa4+xa13+Bph1) in BR43, BR44, BR48, and BR58. Two-gene combination (xa13 and Xa4) materialized in BR53, BR54, BR60, BR73, BR85, and BR86, while identifying a combination of xa13 and Bph1 in BR11, BR41, and BR99. Xa4 was present in 14, xa13 in six, and Bph1 in three lines. Screening the population against Xanthomonas oryzae validated the presence of BB-resistant genes. The consistent finding is that the RILs with a combination of two or more genes express a high level of resistance compared with the RILs with a single gene. The RILs with Xa4 and xa13 expressed more resistance than the lines with xa13 and Bph1. Employing the MAGIC populations approach remains to be effective for gene pyramiding. [ABSTRACT FROM AUTHOR]

Simple Summary: Hybrid rice often has higher yields than comparable inbred varieties. However, hybrids are sometimes more susceptible to insect herbivores. Outbreeding can improve herbivore resistance in hybrids compared to one (a condition called heterosis) or both (called heterobeltiosis) of their parental lines. The frequency of heterosis for resistance has not been assessed under varying soil nitrogen conditions. Nitrogen is predicted to reduce a plant's ability to resist herbivores but increases its ability to compensate for damage, known as tolerance. We examined the resistance and tolerance of eight hybrids and their parental lines to herbivores by exposing plants to the brown planthopper, whitebacked planthopper or yellow stemborer and observing herbivore fitness responses (i.e., resistance) and herbivore-induced changes to plant biomass (i.e., tolerance). There were no consistent trends in relative resistance or tolerance to the herbivores across plant types; however, improved resistance and tolerance were frequently associated with the male parent. Nitrogen reduced resistance and generally increased tolerance to herbivores irrespective of plant type. Across the eight hybrids, relative resistance and relative tolerance were not determined by heterosis or heterobeltiosis. Our results highlight the difficulties in predicting the outcomes of crossing to achieve relatively resistant hybrids. Hybrid rice results from crossing a male-sterile line (the A line) with a pollen doner (the restorer or R line). In 3-line hybrid breeding systems, a fertile B line is also required to maintain A line populations. Heterosis is defined as a condition of traits whereby the hybrid exceeds the average of the parental lines. Heterobeltiosis is where the hybrid exceeds both parents. Hybrid rice may display heterosis/heterobeltiosis for growth, yield and resistance to herbivores, among other traits. In a greenhouse experiment, we assessed the frequency of heterosis for resistance to the brown planthopper (Nilaparvata lugans (BPH)), whitebacked planthopper (Sogatella furcifera (WBPH)) and yellow stemborer (Scirpophaga incertulas (YSB)) in eight hybrids under varying soil nitrogen conditions. We also assessed plant biomass losses due to herbivore feeding as an approximation of tolerance (the plant's capacity to compensate for damage). Nitrogen reduced resistance to all three herbivores but was also associated with tolerance to WBPH and YSB based on improved plant survival, growth and/or yields. Plant biomass losses per unit weight of WBPH also declined under high nitrogen conditions for a number of hybrids, and there were several cases of overcompensation in rice for attacks by this herbivore. There was one case of nitrogen-related tolerance to BPH (increased grain yield) for a hybrid line with relatively high resistance, likely due to quantitative traits. Heterosis and heterobeltiosis were not essential to produce relatively high herbivore resistance or tolerance across hybrids. [ABSTRACT FROM AUTHOR]

The brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae) (BPH), is a major, regionally migratory pest of rice in Asia. Despite intensive migratory studies, the seasonal migratory pattern of this species in the year-round breeding region (i.e. Hainan Island) remains largely unknown. To understand the migration dynamics, we conducted relevant research based on BPH light trap catches on Hainan in 2017–2022. Results showed that the occurrence dynamics of BPH in Hainan oscillated in different years and seasons. Overall, there are 4 migration peak periods on Hainan, with outbound peak periods in April–May and August–September and inbound peak periods in June and October. Trajectory and wind fields showed that in August–September, Hainan had complex meteorological conditions, and the outbound paths of BPH were variable, mainly landing in southeastern Guangxi and southwestern Guangdong. In contrast, April–May was influenced by southeasterly winds, with a wider outbound range and a further distance, landing along northeastern Vietnam from west to east toward Guangxi and Guangdong areas with time. Wind-rain fields, trajectory, and hydrogen isotope showed that in June, southwesterly winds transported BPH northward from the Indochina peninsula, where it was hindered by rainfall in the Leizhou Peninsula area and the migrants will be "rained out" into Hainan. Identically, in October, the interactions between northeasterly winds and rainfall belts on the southwest shore of Hainan increased the opportunities for BPH to migrate southward to reach Hainan. Our results suggest that Hainan is not only an important source of BPH migrating from East Asia but also plays the role of a bridge. [ABSTRACT FROM AUTHOR]

The biogeographical range shift of insect pests is primarily governed by temperature. However, the range shift of seasonal long-distance migratory insects may be very different from that of sedentary insects. Nilaparvata lugens (BPH), a serious rice pest, can only overwinter in tropical-to-subtropical regions, and some populations migrate seasonally to temperate zones with the aid of low-level jet stream air currents. This study utilized the CLIMEX model to project the overwintering area under the climate change scenarios of RCP2.6 and RCP8.5, both in 2030s and 2080s. The overwintering boundary is predicted to expand poleward and new overwintering areas are predicted in the mid-latitude regions of central-to-eastern China and mid-to-southern Australia. With climate change, the habitable areas remained similar, but suitability decreased substantially, especially in the near-equatorial regions, owing to increasing heat stress. The range shift is similar between RCP2.6-2030s, RCP2.6-2080s, and RCP8.5-2030s, but extreme changes are projected under RCP8.5-2080s with marginal areas increasing from 27.2 to 38.8% and very favorable areas dropping from 27.5 to 3.6% compared to the current climate. These findings indicate that climate change will drive range shifts in BPH and alter regional risks differently. Therefore, international monitoring programs are needed to effectively manage these emerging challenges. [ABSTRACT FROM AUTHOR]

Nilaparvata lugens, the brown planthopper (BPH), is a serious pest species. BPHs cause significant damage to rice plants in Korea as well as other countries in East and Southeast Asia. As BPHs cannot survive winter in Korea, they annually migrate into Korea from foreign countries. The BPHs found in Korea are believed to originate from China, but most BPHs in China are also known to originate from Southeast Asia. To understand the origin of Korean BPHs, we conducted a genotyping‐by‐sequencing (GBS) study. We sampled BPHs from five locations in Korea and five countries in Southeast Asia and analyzed the GBS and sequencing results using various methods based on the f statistics and admixture graph analyses. We confirmed that the domestic BPHs shared a greater genetic drift than the BPHs from Southeast Asian populations over several years, implying that a continuous genetic substratum of Korea exists. This genetic substratum is genetically closer to BPHs from the southern part (Thailand and Cambodia) of Southeast Asia than to BPHs from the northern part (Bhutan, Myanmar and Laos) of Southeast Asia. In addition, direct gene flows from Southeast Asia seem possible, so Korea is considered a hotspot where diverse BPH populations mix. Therefore, the origin of Korean BPHs extends beyond China and as far as southern Southeast Asia. This result will help to understand and control the population dynamics of the Korean BPH population. [ABSTRACT FROM AUTHOR]

Rice blast, caused by the fungus Magnaporthe oryzae, and brown planthopper (BPH) infestation are two of the most destructive problems of rice production in China. The development of multi-resistant varieties is widely recognized as the most efficient and environmentally friendly approach to controlling crop diseases and pests. Functional molecular markers (FMMs) have been developed from functional variants in the genic region associated with trait variation, greatly enhancing the efficiency of identifying and pyramiding valuable genes in crop breeding. In this study, two FMMs and a multiplex PCR amplification system were developed for two major broad-spectrum BPH resistance genes, Bph6 and Bph9. With the assistance of FMMs in the multi-resistant rice restorer-line development pipeline, two lines (Huahui7713 and Huahui3006) with blast and BPH resistance were developed by pyramiding three resistance genes Pigm, Bph6 and Bph9. Two new hybrid rice varieties, Weiliangyou7713 and Xuanliangyou3006, derived from Huahui7713 and Huahui3006, have been developed and commercialized in China. Weiliangyou7713 and Xuanliangyou3006 exhibit enhanced resistance to both blast and BPH, while maintaining optimal yield and grain quality. The adoption of Weiliangyou7713 continues to expand, now being cultivated on a large scale, which is promising for its future role in reducing the dependence on chemical fungicides and pesticides in rice production. This suggests that the implementation of Huahui7713 and Huahui3006 in targeted breeding programs could be highly beneficial for developing rice varieties with strong resistance to blast and BPH. [ABSTRACT FROM AUTHOR]

The sugar supplied by rice and the demand by N. lugens can affect the proportion of brachypterous forms in a population. Experiments were conducted to estimate the food ingestion by N. lugens per capita, to determine total food demand in a rice field, and to find the relation of food supply to the proportion of the brachypterous form. The results revealed that the sucrose content tended to decrease with the age of rice. However, the food demand by the N. lugens population dramatically increased in 40–89-day-old rice. The proportion of sugar supply to insect demand decreased as the insect population increased. The relative abundance of short-wing form insects increased when the ratio of sugar supply to insect demand was ≥0.02, but was decreased when the ratio was lower than 0.01. These results are useful for predicting N. lugens dispersal related to sugar supply in rice fields. [ABSTRACT FROM AUTHOR]

Accurate genomic information is essential for advancing genetic breeding research in specific rice varieties. This study presented a gapless genome assembly of the indica rice cultivar Zhonghui 8015 (ZH8015) using PacBio HiFi, Hi-C, and ONT (Oxford Nanopore Technologies) ultra-long sequencing technologies, annotating 43 037 gene structures. Subsequently, utilizing this genome along with transcriptomic and metabolomic techniques, we explored ZH8015's response to brown planthopper (BPH) infestation. Continuous transcriptomic sampling indicated significant changes in gene expression levels around 48 h after BPH feeding. Enrichment analysis revealed particularly significant alterations in genes related to reactive oxygen species scavenging and cell wall formation. Metabolomic results demonstrated marked increases in levels of several monosaccharides, which are components of the cell wall and dramatic changes in flavonoid contents. Omics association analysis identified differentially expressed genes associated with key metabolites, shedding light on ZH8015's response to BPH infestation. In summary, this study constructed a reliable genome sequence resource for ZH8015, and the preliminary multi-omics results will guide future insect-resistant breeding research. [ABSTRACT FROM AUTHOR]

The brown planthopper, Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) and the green rice leafhopper, Nephotettix cincticeps Uhler (Hemiptera: Cicadellidae) feed by sucking phloem sap from rice plants and excreting honeydew containing glucose. It is known that there are resistant rice cultivars against Ni. lugens or Ne. cincticeps, from which insects are unable to suck phloem sap. Here, we developed a simple method using a glucometer to measure glucose concentration in honeydew and use it to evaluate rice resistance against sucking insects. In case of Ni. lugens, the honeydew excreted by sucking a susceptible rice line was large in volume and glucose content. In contrast, the honeydew excreted by sucking a resistant rice line was low in volume and glucose content. In case of Ne. cincticeps, no glucose was detected in the honeydew excreted by sucking a resistant rice line, although more honeydew was excreted from the resistant rice line than the susceptible rice line. Therefore, it was suggested that Ne. cincticeps could not suck phloem sap of the resistant cultivar. Glucose analysis of honeydew using a glucometer would be useful for evaluating sucking inhibition of rice cultivars against Ni. lugens and Ne. cincticeps. [ABSTRACT FROM AUTHOR]

Plants produce various phytochemicals against herbivory, but phytophagous insects have encountered phytochemicals in the co‐evolutionary history between plants and insects. Selection pressure exerted by phytochemicals triggers a preadaptation to insecticide resistance in insect pests that is due to detoxification systems that are common to phytochemicals and insecticides in the insect's body. We investigated the interaction between the host plant resistance of rice cultivars and the brown planthopper, Nilaparvata lugens (Stål) (Hemiptera: Delphacidae). Forty brown planthopper resistance gene loci (BPHs) that are related to phytochemicals in various cultivars of rice inhibit feeding by N. lugens, but this planthopper has developed virulence to resistant rice cultivars possessing some genes. Nilaparvata lugens has also developed resistance to some insecticides as a rapid adaptation to human‐driven selection. We tested the hypothesis that the evolution of insects' resistance to an insecticide is promoted by their encounters with phytochemicals. We compared the virulence of imidacloprid‐resistant and control N. lugens strains toward seven rice cultivars that possess different genes, and we observed that the imidacloprid‐resistant N. lugens had reduced virulence to three rice cultivars, Rathu Heenati (BPH3, BPH17), Babawee (BPH4), and Balamawee (BPH27, three quantitative trait loci), meaning that the development of imidacloprid resistance has a negative impact on the virulence of N. lugens to three cultivars. Our results indicate trade‐offs rather than a co‐relationship between the evolution of insecticide resistance and encounters with host plant defense. [ABSTRACT FROM AUTHOR]

The brown planthopper (BPH) is the most destructive insect pest that threatens rice production globally. Developing rice varieties incorporating BPH-resistant genes has proven to be an effective control measure against BPH. In this study, we assessed the resistance of a core collection consisting of 502 rice germplasms by evaluating resistance scores, weight gain rates and honeydew excretions. A total of 117 rice varieties (23.31%) exhibited resistance to BPH. Genome-wide association studies (GWAS) were performed on both the entire panel of 502 rice varieties and its subspecies, and 6 loci were significantly associated with resistance scores (P value < 1.0e-8). Within these loci, we identified eight candidate genes encoding receptor-like protein kinase (RLK), nucleotide-binding and leucine-rich repeat (NB-LRR), or LRR proteins. Two loci had not been detected in previous study and were entirely novel. Furthermore, we evaluated the predictive ability of genomic selection for resistance to BPH. The results revealed that the highest prediction accuracy for BPH resistance reached 0.633. As expected, the prediction accuracy increased progressively with an increasing number of SNPs, and a total of 6.7K SNPs displayed comparable accuracy to 268K SNPs. Among various statistical models tested, the random forest model exhibited superior predictive accuracy. Moreover, increasing the size of training population improved prediction accuracy; however, there was no significant difference in prediction accuracy between a training population size of 737 and 1179. Additionally, when there existed close genetic relatedness between the training and validation populations, higher prediction accuracies were observed compared to scenarios when they were genetically distant. These findings provide valuable resistance candidate genes and germplasm resources and are crucial for the application of genomic selection for breeding durable BPH-resistant rice varieties. [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 (Oryza sativa L.), a crucial staple food worldwide, faces significant pest challenges that intend to reduce economic yield, notably the brown planthopper (BPH, Nilaparvata lugens Stal.). Serotonin, a neurotransmitter produced in rice is reported to influence the growth and development of the insects feeding upon it besides being involved in the growth and metabolism of rice. Defense responses towards herbivores involve elicitors such as jasmonic acid and salicylic. This study examined the expression pattern of CYP71A1, precursor encoding tryptamine 5-hydroxylase and the effect of salicylic acid, methyl jasmonate and serotonin on BPH damage and serotonin synthesis post-infestation. Serotonin concentration increased in methyl jasmonate and serotonin treatments and is evinced by the high damage score they inflicted on the treated plants. Further, CYP71A1 associated with the conversion of tryptamine to serotonin, gave a deeper understanding of the time of active feeding by the activation of the serotonin-producing gene. [ABSTRACT FROM AUTHOR]

Infestation by various insect pests is the main constraint for growing rice where rice brown planthopper (Nilaparvata lugens Stål) can severely damage rice plants directly through feeding. Therefore, the study aims to detect rice brown planthoppers (BPH) and provide environment-friendly management tactics to mitigate the problem which caused by brown planthoppers. The BPH samples were collected from rice fields of different locations in the Patuakhali of Bangladesh for molecular identification. A molecularly single species of rice brown planthopper, Nilaparavata lugens was identified using mitochondrial cytochrome oxidase subunit I (mtCOI) universal marker. The nucleotide sequences of collected samples were compared with other nucleotide sequences from the GenBank database of NCBI, which make single clades in the phylogenetic tree at an insignificant distance. Moreover, brown planthopper management observations were recorded in laboratory conditions after providing an artificial diet with different treatments of plant-based insecticides Neem oil (1 %, 5 %, and 10 %), Castor oil (1 %, 5 %, and 10 %) where only 20 % sucrose solution was used as negative control and Abamectin (1 %, 5 % and 10 %) were also used as a positive control for comparing the efficacy of plant-based insecticides on rice brown planthoppers. The results showed the highest mortality (100 %) of rice brown planthoppers was recorded by Abamectin 10 %, followed by Abamectin 5 %. Neem 10 % performed better than Abamectin 1 % during 1st hour. Initial after exposure of 2nd hour for Abamectin 1 % revealed greater mortality (59 %) than Neem 10 %. Neem 5 % showed less effect on mortality in brown planthopper than Neem 10 % but was higher than Neem 1 % during 6 h of observation. The Castor oil of 10 % caused higher mortality than the Castor of 5 % but not up to the marks of Abamectin and different concentrations of Neem oil. Castor oil of 1 % and control have shown no mortality of brown planthopper for 6 h of observation.

Abstract Background The brown planthopper (BPH) is a kind of piercing-sucking insect specific to rice, with the damage tops the list of pathogens and insects in recent years. microRNAs (miRNAs) are pivotal regulators of plant–environment interactions, while the mechanism underlying their function against insects is largely unknown. Results Here, we confirmed that OsmiR319, an ancient and conserved miRNA, negatively regulated resistance to BPHs, with overexpression of OsmiR319 susceptible to BPH, while suppression of OsmiR319 resistant to BPH in comparison with wild type. Meanwhile, we identified several targets of OsmiR319 that may mediate BPH resistance. Among them, OsPCF5 was the most obviously induced by BPH feeding, and over expression of OsPCF5 was resistance to BPH. In addition, various biochemical assays verified that OsPCF5 interacted with several MYB proteins, such as OsMYB22, OsMYB30, and OsMYB30C.Genetically, we revealed that both OsMYB22 and OsMYB30C positively regulated BPH resistance. Genetic interaction analyses confirmed that OsMYB22 and OsMYB30C both function in the same genetic pathway with OsmiR319b to mediate BPH resistance. Conclusions Altogether, we revealed that OsPCF5 regulates BPH resistance via association with several MYB proteins downstream of OsmiR319, these MYB proteins might function as regulators of BPH resistance through regulating the phenylpropane synthesis.

Rice is a major global staple crop, but rising temperatures and freshwater shortages have made drought one of the most severe abiotic stresses affecting agriculture. Additionally, rice blast disease and brown planthopper infestations significantly impact yields. Therefore, developing water-saving, drought-resistant, high-yielding, and disease-resistant rice varieties is critical for sustainable rice production. The new water-saving and drought-resistant (WDR) rice ‘Huhan 1516’, bred using marker-assisted selection (MAS) and marker-assisted backcrossing (MABC) techniques, addresses these challenges. This variety is highly adaptable to drought-prone and water-scarce regions such as the Yangtze and Huai River basins. With its high yield, drought tolerance, and broad-spectrum resistance to rice blast (conferred by the Pi2 gene) and brown planthopper (BPH), ‘Huhan 1516’ is suitable for various farming systems and environments. Field trials show that this variety outperforms control varieties by 2.2% in yield and exhibits moderate resistance to both rice blast and brown planthopper. ‘Huhan 1516’ has been recognized as a new water-saving and drought-resistant rice variety by the state, and as a released cultivar, it has great potential for market promotion and application.

The Cleavage Stimulation Factor (CstF) complex, consisting of three subunits, is essential for the 3′ end processing of precursor messenger RNA (pre-mRNA). In mammals, this complex includes CstF50, CstF64, and CstF77, named according to their molecular weights, and these proteins are conserved across many organisms. However, the functional roles of the three CstF genes (NlCstF50, NlCstF64, and NlCstF77) in Nilaparvata lugens, a major rice pest, have not been fully explored. This study identified and characterized the sequences of these genes, with proteins encoded by NlCstF50, NlCstF64, and NlCstF77 consisting of 439, 419, and 732 amino acids, respectively. These proteins are conserved among various insect species. Spatio-temporal expression analysis revealed that these genes are expressed at all developmental stages and in various tissues, with peak levels in eggs and testes. RNA interference (RNAi) targeting one or all three NlCstF genes resulted in a reduction in gene expression by 68% to 90% at 72 h post-injection, indicating that multi-gene dsRNA can achieve similar silencing outcomes as single-gene dsRNA. Knocking down one or all three NlCstF genes caused significant lethal phenotypes and molting disruptions. Mortality rates increased from 62.5% (dsNlCstF50) to 95.4% (dsNlCstF(50+64+77)). Additionally, silencing these genes reduced the number of eggs laid per female and hatch rates. These results highlight the critical role of NlCstF genes in the development and reproduction of N. lugens, suggesting their potential as targets for RNAi-based pest control strategies.

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]

Simple Summary: Hybrid rice is produced by crossing a male sterile rice line (the A line) with a pollen doner that restores fertility (the restorer line). The consequential outbreeding can result in plant growth and yields that are above the average of the parental lines (a condition called heterosis). This gives rise to a normally higher productivity of hybrids compared to pure-line (inbred) rice varieties. However, hybrid rice has also been associated with higher herbivore damage compared to inbreds. In particular, susceptibility to the whitebacked planthopper (Sogatella furcifera) has been linked to the A line in early generation hybrids. We tested whether hybrids had heterosis for resistance to the whitebacked planthopper, brown planthopper (Nilaparvata lugens) and yellow stemborer (Scirpophaga incertulas) in a series of greenhouse and field experiments. In the field plots, heterosis resulted in relatively high hybrid yields. There were few cases of heterosis for resistance to herbivores in the greenhouse or field and only one of eight A lines was associated with susceptibility to planthoppers. Susceptibility to the yellow stemborer was largely due to plant physiology: larger, fast-growing and late-maturing varieties, including hybrids, were more vulnerable to stemborers. Therefore, susceptibility to stemborers was often a consequence of heterosis for plant biomass. We make a series of recommendations to improve screening and breeding for resistance to herbivores in hybrid rice. Three-line hybrid rice is produced by crossing male sterile (A line) rice with a fertility-restorer (R line). Fertile lines (B lines) are also required to maintain A line seed for breeding programs. We used a range of hybrids and their parental lines to assess the frequency and nature of heterosis for resistance to the whitebacked planthopper (Sogatella furcifera), brown planthopper (Nilaparvata lugens) and yellow stemborer (Scirpophaga incertulas). Heterosis is defined as trait improvement above the average of the parental lines as a result of outbreeding. Based on the results from a greenhouse study that challenged hybrids and their parental lines with each herbivore species, we found that susceptibility to planthoppers was associated with one of the eight A lines tested, but resistance was improved by crossing with a relatively resistant restorer. Higher frequencies of heterosis for susceptibility in comparisons between hybrids and their B lines suggest that susceptibility was not related to the cytoplasmic genomes of the associated sterile A lines. Furthermore, because none of the parental lines possessed currently effective resistance genes, improved resistance against planthoppers was probably due to quantitative resistance. In a related field trial, hybrids had generally higher yields than their fertile parents and often produced larger grain; however, they were often more susceptible to stemborers, leaffolders (Cnaphalocrocis medinalis) and other caterpillars (Rivula atimeta). This was largely a consequence of hybrid heterosis for plant biomass and was strongly affected by crop duration. We make a series of recommendations to improve hybrid breeding to reduce the risks of herbivore damage. [ABSTRACT FROM AUTHOR]

BACKGROUND: Previous studies of brown planthopper (BPH), Nilaparvata lugens, showed that carrying the plant pathogenic virus, rice ragged stunt virus (RRSV), enhanced the lethality of the entomopathogenic fungus, Metarhizium anisopliae (YTTR). The underlying mechanism for this was not established but a serine protease cascade was hypothesized to be involved. RESULTS: Two immune response genes, NlKPI and NlVenomase, were identified and shown to be involved. The synthesized double‐strand RNA (dsRNA) techniques used in this study to explore gene function revealed that treatment with dsRNA to silence either gene led to a higher BPH mortality from M. anisopliae infection than the dsRNA control treatment. NlKPI and NlVenomase play vital roles in BPH immunity to defend against alien pathogens. Both genes participate in the immune response process of BPH against co‐infection with RRSV and M. anisopliae YTTR by regulating the expression of antimicrobial peptides and phenoloxidase activity. CONCLUSION: Our study provided new targets for BPH biocontrol and laid a solid foundation for further research on the interaction of virus‐insect‐EPF (entomopathogenic fungus). © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Simple Summary: The brown planthopper (BPH, Nilaparvata lugens Stål) is the most destructive pest in rice. Understanding the endosymbiont communities hosted by this insect is a prerequisite for controlling BPH rice infestations. This study reveals the diversity and dynamics of endosymbiotic fungi in the developmental stages and various tissues of BPH by means of circular consensus sequencing (CCS), and we found three dominant yeast-like symbionts (YLSs) in almost all samples and the significant biomarkers between female and male adults. This suggests that these endosymbionts are necessary for BPH survival. This study provides a comprehensive survey of symbiotic fungi in the BPH and offers new strategies for pest management in rice. Endosymbiotic fungi play an important role in the growth and development of insects. Understanding the endosymbiont communities hosted by the brown planthopper (BPH; Nilaparvata lugens Stål), the most destructive pest in rice, is a prerequisite for controlling BPH rice infestations. However, the endosymbiont diversity and dynamics of the BPH remain poorly studied. Here, we used circular consensus sequencing (CCS) to obtain 87,131 OTUs (operational taxonomic units), which annotated 730 species of endosymbiotic fungi in the various developmental stages and tissues. We found that three yeast-like symbionts (YLSs), Polycephalomyces prolificus, Ophiocordyceps heteropoda, and Hirsutella proturicola, were dominant in almost all samples, which was especially pronounced in instar nymphs 4–5, female adults, and the fat bodies of female and male adult BPH. Interestingly, honeydew as the only in vitro sample had a unique community structure. Various diversity indices might indicate the different activity of endosymbionts in these stages and tissues. The biomarkers analyzed using LEfSe suggested some special functions of samples at different developmental stages of growth and the active functions of specific tissues in different sexes. Finally, we found that the incidence of occurrence of three species of Malassezia and Fusarium sp. was higher in males than in females in all comparison groups. In summary, our study provides a comprehensive survey of symbiotic fungi in the BPH, which complements the previous research on YLSs. These results offer new theoretical insights and practical implications for novel pest management strategies to understand the BPH–microbe symbiosis and devise effective pest control strategies. [ABSTRACT FROM AUTHOR]

The Brown planthopper, Nilapavarta lugens (Stål) (BPH) is a major pest of rice after the adoption of the Green Revolution. Its outbreaks are frequently linked to climate variability and change, posing almost all rice varieties in Indonesia at risk, resulting in economic losses due to reduced production. The amount of information available about its current and future potential distribution as well as the influencing factors are still limited. The objective of this study is to examine the impact of climate variability on BPH and to assess the projection of the BPH potential distribution under different climate scenarios. Maximum entropy (MaxEnt) was applied to predict the current and future potential distribution of BPH over Indonesia. This study used data on BPH-affected areas, rainfall and temperature, and the Ocean Nino Index (ONI) on a monthly interval to examine the linkage between climate and BPH affected areas. The global-climate models from phase 6 of coupled model intercomparison project (CMIP6) for period 2041–2060 were used to examine the variations in 19 bioclimatic variables for two shared socioeconomic pathways (SSPs) compared to baseline period (1971–2000). The findings concluded that the dynamics of BPH damaged areas were strongly influenced by higher temperature and rainfall in dry season associated with La Niña events. Precipitation of driest month, precipitation seasonality, mean temperature of driest quarter and temperature seasonality were the most affected factors in the distribution of BPH. Our results highlight BPH distribution was expected to increase to 2.4% and 3.02% (moderately suitable), 1.88% and 1.95% (suitable), 2.59% and 2.76% (highly suitable) respectively under SSP2-4.5 and SSP5–8.5. These findings could serve as early warnings to adjust agricultural practices and implement tailored pest management methods to effectively address the shifting pattern of BPH in the future. [ABSTRACT FROM AUTHOR]

The brown planthopper Nilaparvata lugens (Stål) (BPH) is a main rice pest in China and many other Asian countries. In the control of BPH, the application of insect-resistant rice has proven to be quite effective. Secondary metabolites are essential weapons in plants' defense against phytophagous insects. Studies have found that differences in the content of secondary metabolites play a crucial role in determining whether rice exhibits resistance or susceptibility to BPH. Simultaneously, symbionts are essential to the BPH. Nevertheless, there is limited research on the impact of secondary metabolites on the symbionts within BPH. Therefore, investigating the influence of secondary metabolites on both BPH and their symbionts is significant for the control of BPH. In this experiment, newly emerged female adults of BPH were fed artificial diets containing 10 different secondary metabolites. The results indicated that methyl jasmonate had inhibitory effects on the survival rate, weight gain, and reproductive capacity of BPH. Using qPCR methods, it was discovered that the number of symbiotic fungi (Ascomycetes symbionts) within BPH significantly decreased under methyl jasmonate stress. In conclusion, this experiment has preliminarily revealed the inhibitory effects of methyl jasmonate on BPH and its symbionts, demonstrating its potential for controlling BPH. [ABSTRACT FROM AUTHOR]

The brown planthopper, Nilaparvata lugens (Stål), a type of rice pest, immigrates from southern China to western Japan by drifting in the southwesterly environment during the Baiu/Meiyu rainy season. This study aims to investigate the preferable weather patterns for the immigration of brown planthoppers across the East China Sea. We conducted immigration runs using an advection diffusion model for brown planthoppers and projected the possibility of them landing in Kyushu in the model run onto 64 weather map patterns typically observed in June and July, identified by the self-organizing map analysis. The results showed that the immigration occurred under two specific weather map patterns: flow stagnation around western Japan and a low-level jet blowing over the East China Sea. Consistency between landing cases in model runs and the occurrence of the two weather patterns was found in the intraseasonal and interannual variability. We also estimated the change in the frequency of brown planthopper arrival in Kyushu based on the climate change dataset, the database for Policy Decision Making for Future climate change (d4PDF). It was found that the flow stagnation patterns increased in response to global change, at least in the d4PDF dataset. Finally, risk assessment for temperature change and a comparison with trap observations were discussed. [ABSTRACT FROM AUTHOR]

Carbamate insecticides have been used for over four decades to control brown planthopper, Nilaparvata lugens, but resistance has been reported in many countries, including the Republic of Korea. The bioassay results on resistance to fenobucarb showed that the LC50 values were 3.08 for the susceptible strain, 10.06 for the 2015 strain, and 73.98 mg/L for the 2019 strain. Compared to the susceptible strain, the 2015 and 2019 strains exhibited resistance levels 3.27 and 24.02 times higher, respectively. To elucidate the reason for the varying levels of resistance to fenobucarb in these strains, mutations in the acetylcholinesterase 1 (ACE1) gene, the target gene of carbamate, were investigated, but no previously reported mutations were confirmed. Through RNA-seq analysis focusing on the expression of detoxification enzyme genes as an alternative resistance mechanism, it was found that the carboxylesterase gene Nl-EST1 was overexpressed 2.4 times in the 2015 strain and 4.7 times in the 2019 strain compared to the susceptible strain. This indicates a strong correlation between the level of resistance development in each strain and the expression level of Nl-EST1. Previously, Nl-EST1 was reported in an organophosphorus insecticide-resistant strain of Sri Lanka 2000. Thus, Nl-EST1 is crucial for developing resistance to organophosphorus and carbamate insecticides. Resistance-related genes such as Nl-EST1 could serve as expression markers for resistance diagnosis, and can apply to integrated resistance management of N. lugens.

In recent decades, research on developing and deploying resistant rice has accelerated due to the availability of modern molecular tools and, in particular, advances in marker-assisted selection. However, progress in understanding virulence adaptation has been relatively slow. This review tracks patterns in virulence adaptation to resistance genes (particularly Bph1, bph2, Bph3, and bph4) and examines the nature of virulence based on selection experiments, responses by virulent populations to differential rice varieties (i.e., varieties with different resistance genes), and breeding experiments that interpret the genetic mechanisms underlying adaptation. The review proposes that varietal resistance is best regarded as a combination of minor and major resistance traits against which planthoppers develop partial or complete virulence through heritable improvements that are reversable or through evolutionary adaptation, respectively. Agronomic practices, deployment patterns, and herbivore population pressures determine the rates of adaptation, and there is growing evidence that pesticide detoxification mechanisms can accelerate virulence adaptation. Research to delay adaptation has mainly focused on gene pyramiding (i.e., including ≥ two major genes in a variety) and multilines (i.e., including ≥ two resistant varieties in a field or landscape); however, these strategies have not been adequately tested and, if not managed properly, could inadvertently accelerate adaptation compared to sequential deployment. Several research gaps remain and considerable improvements in research methods are required to better understand and manage virulence adaptation.

Several studies have reported higher damage from insect herbivores to hybrid compared to inbred (pure line) rice. We used a collection of 20 hybrid and 12 inbred genotypes from diverse origins to test the hypotheses that hybrid rice susceptibility is due to (a) the hybrid plant type and/or (b) rice phylogeny. We challenged the genotypes with Nilaparvata lugans (BPH), Sogatella furcifera (WBPH) and Scirpophaga incertulas (YSB) in greenhouse and screenhouse bioassays and monitored herbivores in field plots. We used single nucleotide polymorphic (SNP) markers to assess genetic similarities between the genotypes and found that the hybrids and inbreds formed two distinct clusters regardless of origin. In the screenhouse, hybrids were more susceptible than inbreds to YSB; however, resistant hybrids and susceptible inbreds were also apparent from both the screenhouse and field plots. Plant biomass was the best predictor of susceptibility to YSB. Plant origin had a greater effect than plant type on susceptibility to BPH and WBPH. WBPH was the most abundant planthopper in the field plots where numbers were highly correlated with planthopper fitness in the greenhouse bioassays. Our results provide evidence that high-yielding hybrids that are relatively resistant to herbivores can be achieved through careful breeding. The avoidance of susceptible genotypes during breeding should remain a key element of integrated rice pest management.