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BACKGROUND: Widespread resistance of insect pests to insecticides and transgenic crops in the field is a significant challenge for sustainable agriculture, and calls for the development of novel alternative strategies to control insect pests. One potential resource for the discovery of novel insecticidal molecules is natural toxins, particularly those derived from the venoms of insect predators. RESULTS: In this study, we identified three insecticidal proteinaceous toxins from the venom glands (VGs) of the predatory stink bug, Arma custos (Hemiptera: Asopinae). Transcriptomic analysis of A. custos VGs revealed 151 potentially secreted VG‐rich venom proteins. Three VG‐rich venom proteins (designated AcVP1 ~ 3) were produced by overexpression in Escherichia coli. Injection of the recombinant proteins into tobacco cutworm (Spodoptera litura) larvae showed that all of the three recombinant proteins caused paralysis, liquefaction and death. Injection of recombinant proteins into rice brown planthopper (Nilaparvata lugens) nymphs showed higher insecticidal activities, among which a trypsin (AcVP2) caused 100% mortality postinjection at 1.27 pmol mg−1 body weight. CONCLUSION: A natural toolkit for the discovery of insecticidal toxins from predatory insects has been revealed by the present study. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: The transcription product of tramtrack (ttk) is an important transcription factor which plays many roles in the regulation of the development, differentiation and chromosome recombination of organisms. Few studies have been reported on the specific functions of ttk in other insects except Drosophila melanogaster. Our aims are to reveal the ttk effects on development and courtship of male rice pest brown planthopper (BPH), Nilaparvata lugens. RESULTS: In this study, we first assayed spatiotemporal expression of ttk in BPH, then treated the fourth nymphs of BPH with dsttk. We found most individuals died before emerging to adults, the adult eclosion rate was only 18.89%. No courtship behavior was found in individuals injected with dsttk. Further research showed that the main frequency of courtship vibration signal (CVS) 431.3 Hz in the individuals injected with dsttk was significantly higher than 223 Hz in the individuals injected with dsGFP, and female adults nearly had no response to the 431.3 Hz CVS. CONCLUSION: We found that about 81% of the 4‐instar nymphs of BPH treated with dsttk died before they emerged as adults, the successfully emerged adults emitted the 431.3 Hz CVS to which female adults did not respond and lost the ability of courtship. This was first finding about the functions of ttk in rice planthopper and illustrated the potential of ttk as target for RNAi to control rice planthopper. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Background: The brown planthopper (BPH) is an economically significant pest of rice. Bph3 is a key BPH resistance gene. However, the proteomic response of rice to BPH infestation, both in the presence and absence of Bph3, remains largely unexplored. Results: In this study, we employed tandem mass tag labeling in conjunction with liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis to identify differentially expressed proteins (DEPs) in rice samples. We detected 265 and 125 DEPs via comparison of samples infected with BPH for 2 and 4 days with untreated samples of the BPH-sensitive line R582. For the Bph3 introgression line R373, we identified 29 and 94 DEPs in the same comparisons. Bioinformatic analysis revealed that Bph3 significantly influences the abundance of proteins associated with metabolic pathways, secondary metabolite biosynthesis, microbial metabolism in diverse environments, and phenylpropanoid biosynthesis. Moreover, Bph3 regulates the activity of proteins involved in the calcium signaling pathway, mitogen-activated protein kinase (MAPK) signaling pathway, and plant hormone signal transduction. Conclusions: Our results indicate that Bph3 enhances the resistance of rice to BPH mainly by inhibiting the down-regulation of proteins associated with metabolic pathways; calcium signaling, the MAPK signaling pathway, and plant hormone signal transduction might also be involved in BPH resistance induced by Bph3. [ABSTRACT FROM AUTHOR]

A series of novel 3‐(6‐methyltriazinone)‐3,4‐dihydrobenzo[b][1,5]diazin‐2(1H)‐one derivatives was designed and synthesized as conformationally restricted analogues of insecticide pymetrozine. Conformational and physicochemical properties analyses indicated the rationality in reducing the energy barrier between the lowest‐energy and predicted bioactive conformations, as well as pesticide‐likeness. Insecticidal bioassays showed that the optimal compound VI‐6b exhibited a mortality rate of 67.7% against Aphis craccivora at 400 mg L−1. The molecular docking study of VI‐6b within the Nilaparvata lugens TRPV channel elucidated the predicted binding mode, wherein VI‐6b forms hydrogen bonds with Arg646 and Glu727, while engaging in π‐π interactions with Phe688. However, physicochemical properties revealed that low lipophilicity and poor aqueous solubility limited the insecticidal efficacy of these novel compounds. This study provides valuable insights for the future design of insecticides targeting the TRPV channel. [ABSTRACT FROM AUTHOR]

Background: Nilaparvata lugens is one of the most destructive pests of rice. RNAi-based N. lugens control offers one alternative strategy to traditional chemical insecticides. However, selection of potential target for RNAi against N. lugens remains a major challenge. Only two target genes for nuclear transgenic N. lugens-resistant plants have been screened. Importantly, only one or few potential target genes against N. lugens were screened every time by knowledge of essential genes from model organisms in previous study. Results: Here, in silico genome-wide selection of potential target genes against N. lugens through homology comparison was performed. Through genome synteny comparisons, about 3.5% of Drosophila melanogaster genome was found to have conserved genomic synteny with N. lugens genome. By using N. lugens proteins to search D. melanogaster homologs defining lethal or sterile phenotype, 358 N. lugens genes were first screened as putative target genes. Transgenic rice lines expressing dsRNA of randomly selected gene (NlRan or NlSRP54) from 358 putative target genes enhanced resistance to N. lugens. After expression check and safety check, 115 N. lugens genes were screened as potential target candidates. Conclusion: The combined efforts in this study firstly provide one in silico genome-wide homology-based screening approach for RNAi-based target genes against N. lugens, which not only offer one new opportunity to batch select potential target candidates in pests of interest, but also will facilitate the selection of RNAi target in many pest species by providing more than one hundred potential target candidates. [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]

Simple Summary: The brown planthopper (Nilaparvata lugens) is a major pest threatening rice crops, especially in Asia and Africa, causing damage and transmitting harmful viruses. Current control strategies, such as the use of chemical pesticides, are becoming increasingly ineffective due to the development of resistance in pest populations. RNA interference (RNAi) is a promising alternative for silencing essential genes in pests. This study focuses on the NlCPSF30 gene (homolog of mammalian CPSF30), which is crucial for mRNA processing in brown planthoppers. By using RNAi to knock down the NlCPSF30 gene, we observed marked reductions in survival rates and notable developmental defects in the pests. These findings highlight the potential of targeting NlCPSF30 for developing RNAi-based pest control strategies. The brown planthopper (Nilaparvata lugens) is a major pest threatening global rice production, significantly reducing yields annually. As N. lugens increasingly develops resistance to conventional control methods, such as chemical pesticides, there is an urgent need for innovative and sustainable pest management strategies. Cleavage and Polyadenylation Specificity Factor 30 (CPSF30) is a key protein involved in mRNA 3′ end processing, yet its function in N. lugens remains poorly understood. This study aims to elucidate the role of CPSF30 in the growth and development of N. lugens and evaluate its potential as a target for RNA interference (RNAi)-based pest control strategies. We cloned and characterized the cDNA sequence of NlCPSF30, which encodes a protein of 341 amino acids containing five CCCH zinc-finger domains and two CCHC zinc-knuckle domains. Sequence alignment revealed that NlCPSF30 is highly conserved among insect species, particularly in the zinc-finger domains essential for RNA binding and processing. Phylogenetic analysis showed that NlCPSF30 is closely related to CPSF30 proteins from other hemipteran species. Expression analysis indicated that NlCPSF30 is most highly expressed in the fat body and during the adult stage, with significantly higher expression in females than in males. RNAi-mediated silencing of NlCPSF30 in third-instar nymphs resulted in severe phenotypic abnormalities, including disrupted molting and increased mortality following injection of double-stranded RNA (dsRNA) targeting NlCPSF30. Moreover, it influenced the expression of genes associated with hormone regulation, namely NlHry, NlE93, and NlKr-h1. These results suggest that NlCPSF30 is integral to critical physiological processes, with its disruption leading to increased mortality. Our findings identify NlCPSF30 as an essential gene for N. lugens' survival and a promising target for RNAi-based pest management strategies. This study provides a valuable molecular target and theoretical insights for developing RNAi-based control methods against N. lugens. [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]

A series of new 5-(trifluoromethyl)-benzo[d]imidazole linked N-phenylamide compounds was designed and synthesized using 1-chloro-2-nitro-4-(trifluoromethyl)benzene as raw material via five steps. Their structures were confirmed by 1H NMR, 13C NMR and HRMS. The bioassay results indicated that some of them exhibited moderate insecticidal activity (>50% inhibition) against Mythimna separata and Nilaparvata lugens at 500 μg/mL. [ABSTRACT FROM AUTHOR]

BACKGROUND: The RNA interference (RNAi) efficiency of double‐stranded RNA (dsRNA) delivery to insects by various methods is different and the reduced efficacy of feeding dsRNA is partly due to the presence of DNA/RNA non‐specific endonuclease in the insect gut. However, the mechanism leading to the low RNAi efficiency of Nilaparvata lugens by feeding remains elusive. RESULTS: In this study, we identified a putatively DNA/RNA non‐specific endonuclease gene in the N. lugens genome database that was highly expressed in the first nymphal instar and the midgut. Different expression levels of NldsRNase after feeding and injection suggested that NldsRNase might interfere with oral RNAi in N. lugens. A co‐delivery RNAi strategy further revealed that the presence of NldsRNase reduces RNAi efficiency. In vitro dsRNA degradation experiments also showed that the stability of dsRNA was higher in a gut mixture from nymphs injected with dsNldsRNase. These results support the idea that the low oral RNAi response observed in N. lugens is likely due to the presence of NldsRNase. CONCLUSIONS: Our study provides insight into the differences in RNAi response between the injection and feeding of dsRNA in N. lugens and sheds light on the mechanisms underlying the reduced efficacy of RNAi via feeding. These findings may help to inform the development of more‐effective RNAi‐based strategies controlling N. lugens and other insect pests. © 2024 Society of Chemical Industry. [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]

ABSTRACT The recent invasion of the fall armyworm (FAW) into Asia not only has had a major impact on maize yield but is feared to also pose a risk to rice production. We hypothesized that the brown planthopper (BPH) may aggravate this risk based on a recently discovered mutualism between the planthopper and the rice striped stem borer. Here we show that BPH may indeed facilitate a shift of FAW to rice. FAW females were found to strongly prefer to oviposit on BPH‐infested rice plants, which emitted significantly elevated levels of five volatile compounds. A synthetic mixture of these compounds had a potent stimulatory effect on ovipositing females. Although FAW caterpillars exhibited relatively poor growth on both uninfested and BPH‐infested rice, a considerable portion completed their development on young plants. Moreover, FAW were found to readily pupate and survive in exceedingly moist soils typical for rice cultivation, further highlighting FAW's potential to switch to rice. We conclude that BPH, by changing the bouquet of volatiles emitted by rice plants, may greatly facilitate this switch. These findings, together with a current increase of nonflooded upland rice in Asia, warrant careful monitoring and specific control measures against FAW to safeguard Asian rice production. [ABSTRACT FROM AUTHOR]

Spiders are an abundant group of natural enemies preying on insect pests in agroecosystem. But their potential in biological control has not been fully realized due to difficult mass production. One hindrance is the intense intraspecific aggression in spiders. Neurotransmitters such as serotonin play important roles in modulating aggression. Here, we investigated the regulatory function of serotonin (5‐hydroxytryptamine [5‐HT]) signaling in the intraspecific aggression in a wandering spider Pardosa pseudoannulata (Araneae, Lycosidae). The aggression was quantified with 5 escalated aggression behaviors as approach, chasing, lunging, boxing, and biting. Virgin (VG) females exhibited higher aggression levels but less 5‐HT content than post‐reproductive (PR) females. Systemic increase of 5‐HT via 5‐HT injection decreased aggression, while decrease of 5‐HT via RNA interference (RNAi) of the tryptophan hydroxylase gene, increased aggression. The involvement of the four 5‐HT receptors were determined via individual or combined RNAi. Co‐RNAi of the three 5‐HT1 genes increased overall aggression with decreased incidents of approach, chasing, lunging, and increased biting. RNAi of 5‐HT1B decreased approach and increased biting, whereas RNAi of 5‐HT1A or 5‐HT1C did not affect aggression. RNAi of 5‐HT7 decreased approach only. Therefore, different 5‐HT receptor types contribute to different aspects of the inhibitory effects of 5‐HT on aggression and provide several pharmacological targets for manipulating spider aggression. 5‐HT injection did not affect spiders’ predation on their insect prey, the brown planthopper Nilaparvata lugens. The findings reveal 1 neuronal mechanism regulating intraspecific aggression in spiders and provide an insight in developing aggression suppression strategies for spider mass rearing. [ABSTRACT FROM AUTHOR]

Rompin has played an active role in Malaysia's rice production for several decades. However, rice production faces a threat, particularly from the hemipteran insect pests. There is limited documentation on the abundance of these insects and their relationship with weather factors. Therefore, this study aimed to determine the abundance of hemipterans in different growth stages and to understand the effects of weather factors on their population in rice fields. The study was conducted in farmers' rice fields in Rompin, Pahang, Malaysia, during the main and off-season rice planting. Sweep nets, yellow sticky traps, and yellow pan traps were utilized in each plot. Trapped insects were identified based on the rice planting seasons and growth stages. The trends of weather factors such as rainfall, temperature, light intensity, and wind speed were analysed and correlated with insect abundance. A total of 23 023 individuals belonging to six families and eleven species of the hemipteran order were recorded. Nine of these species were pests, namely Leptocorisa oratorius (Fabricius) (2.05%), Maiestas dorsalis (Motschulsky) (41.93%), Nephotettix virescens (Distant) (1.52%), Nephotettix nigropictus (Stål) (0.03%), Scotinophara sp. (4.92%), Nilaparvata lugens (Stål) (28.18%), Sogatella furcifera (Horváth) (17.75%), Nezara viridula (Linnaeus) (0.01%) and Scotinophara coarctata (Fabricius) (2.88%). The other two species were predators, Cyrtorhinus lividipennis (Reuter) (0.55%) and Polytoxus fuscovittatus (Stål) (0.19%). Maiestas dorsalis, N. lugens, S. furcifera, and Scotinophara sp. were found in significantly (df=10, F=5.707, P<0.01) higher numbers and exceptionally high during rice's late vegetative and early reproductive stages. The maximum temperature significantly (R²>0.5 & P<0.05) increased during the main season, while wind speed increased significantly (R²>0.5 & P<0.05) during the offseason. Wind speed significantly positive correlated (r>0.5 & P<0.05) with N. virescens, S. furcifera, L. oratorius, and Scotinophara sp. On the other hand, rainfall exhibited a significant negative correlation (r>-0.5 &P<0.05) with L. oratorius. Various pest species and their high populations in this study pose a significant threat to plants due to their preferences for different plant parts and strata. [ABSTRACT FROM AUTHOR]

Rice stripe mosaic virus (RSMV) belongs to the Cytorhabdovirus species in the Rhabdoviridae family. Recently, RSMV was widely spread in East Asia and caused severe yield losses. RSMV is transmitted by the planthopper vectors, Recilia dorsalis, Nephotettix virescens, and Nilaparvata lugens, that mostly affect rice. The adult vectors can hibernate, transmit the virus, lay eggs on rice plants, and, finally, multiply in subsequent generations, resulting in new infection outbreaks. RSMV-infected rice varieties display striped mosaicism, mild dwarfism, stiff and twisted leaves, delayed heading, short panicles with large unfilled grains, and yield reduction. In nature, the infection of multiple pathogens in the same host is widespread, which is defined as co-infection. It can be antagonistic or synergistic. Pathological synergistic effects between RSMV and other viruses can generate strains with new genetic characteristics, leading to unpredictable epidemiological consequences. After the first identification of RSMV in 2015, significant advancements in understanding the disease's characteristics, symptoms, cycles, geographic distribution, potential vectors, and synergistic interaction, as well as its management strategies, were developed. To reduce the damage due to RSMV infection, many scientists have recommended pest control techniques to target adult vectors. It is also essential to confirm the actual time of monitoring, development of resistant varieties, and changes in cultivation systems. Due to the limitations of the conventional plant disease control technologies, improvements in efficiency and safety are in high demand. Therefore, to find efficient and environmentally safe controls to mitigate these challenges, reviews of research are the foremost step. In this review, we summarize the basic epidemiological information about the origin of RSMV and its infection symptoms in the field, synergistic interaction with viruses during co-transmission, yield losses, formulation of the disease cycle, and control strategies from several case studies. Finally, we recommend the formulation of the disease cycle and management strategies of RSMV infection. [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]

The predatory bug Cyrtorhinus lividipennis Reuter (Hemiptera: Miridae) is an important biological control agent for planthoppers, such as Nilaparvata lugens (Stål) (Hemiptera: Delphacidae), and leafhoppers in rice fields (Oryza sativa L., Poaceae). In this study, the sublethal effects of azoxystrobin and difenoconazole, two fungicides extensively used in rice production, on this predatory bug were investigated. The results indicated that exposure to the two fungicides at the third instar had no influence on developmental duration, but difenoconazole resulted in a 25.2% decrease in the lifespan of adult males. When exposed as newly emerged adults, azoxystrobin caused a 33.5% decrease in female longevity. The pre‐oviposition period of azoxystrobin‐treated females mating with azoxystrobin‐treated males was shortened by 44.9%, compared with the control, whereas the pre‐oviposition period of difenoconazole‐treated females mating with control males was lengthened by 32.2% compared with the control group. However, the two fungicides had no effect on fecundity and egg hatchability. Furthermore, the two fungicides did not impact the average consumption of C. lividipennis of N. lugens individuals. They did stimulate the response of C. lividipennis males to rice plants infested by N. lugens in a two‐choice H‐shaped olfactometer test. Also, the predatory capacity of C. lividipennis males was increased after exposure to difenoconazole, whereas the predatory capacity of females was decreased after exposure to the two fungicides. Overall, our results indicated that azoxystrobin and difenoconazole pose no notable risk to C. lividipennis. These findings establish a foundation for the rational and coordinated utilization of fungicides and biological control agents in rice ecosystems. [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]

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]

Brown planthopper (BPH) is the most destructive insect pest of rice. Drought is the most detrimental environmental stress. BPH infestation causes adaxial leaf-rolling and bulliform cells (BCs) shrinkage similar to drought. The BC-related abaxially curled leaf1 (ACL1) gene negatively regulates BPH resistance and drought tolerance, with decreased cuticular wax in the gain-of-function mutant ACL1-D. ACL1 shows an epidermis-specific expression. The TurboID system and multiple biochemical assays reveal that ACL1 interacts with the epidermal-characteristic rice outermost cell-specific (ROC) proteins. ROC4 and ROC5 positively regulate BPH resistance and drought tolerance through modulating cuticular wax and BCs, respectively. Overexpression of ROC4 and ROC5 both rescue ACL1-D mutant in various related phenotypes. ACL1 competes with ROC4/ROC5 in homo-dimer and hetero-dimer formation, and interacts with the repressive TOPLESS-related proteins. Altogether, we illustrate that ACL1–ROC4/5 complexes synergistically mediate drought tolerance and BPH resistance through regulating cuticular wax content and BC development in rice, a mechanism that might facilitate BPH-resistant breeding. Brown planthopper is a rice-specific piercing-sucking pest. This study reveals that ACL1-ROC4/5 complexes regulate both brown planthopper resistance and drought tolerance in rice through modulating bulliform cell development and cuticular wax content. [ABSTRACT FROM AUTHOR]

The Nilaparvata muiri (Hemiptera: Delphacidae) is a sibling species of a destructive rice insect pest, the brown planthopper (BPH), Nilaparvata lugens. Here, we generated a high-quality chromosome-level genome assembly of N. muiri using a combination of the PacBio HiFi sequencing, Illumina short-read sequencing and Hi-C scaffolding technologies. The genome assembly (524.9 Mb) is anchored to 15 pseudochromosomes, with a scaffold N50 of 43.3 Mb and 99.1% BUSCO completeness. It contains 188.1 Mb repeat sequences and 13204 protein-coding genes. As a closely related species within the same genus as the significant pest, N. lugens, the chromosome-level genome assembly of N. muiri will provide important support for the better analysis of pathogenicity mechanisms of N. lugens based on comparative genomics. [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]

• Brown Planthopper is a serious threat to rice crop, posing a significant risk to food security. • To combat the damage, molecular breeding stands as an efficient approach by utilizing resistance genes. • Accordingly, a sophisticated marker assisted breeding technique was employed with SSRs and SNPs to introduce BPH genes from M229 and 10–3 donors into susceptible Telangana Sona. • Five backcross lines (BC 1 (a)−14, BC 1 (a)−19, BC 1 (b)−2, BC 1 (b)−4, BC 1 (b)−5) from both the crosses were identified as potential materials, displaying grain characteristics similar to Telangana Sona. Brown Planthopper (BPH) is one of the most destructive insect pests of rice that threatens food security. Molecular breeding through the use of resistance genes per se would be an economic and efficient way to combat the damage caused by BPH. Telangana Sona (TS) is an elite, popular and a high yielding rice variety susceptible to the infestation of BPH causing severe yield losses. In the current investigation, a marker-assisted backcross breeding approach using gene-specific Simple Sequence Repeats (SSRs) and designed Single Nucleotide Polymorphisms (SNPs) was employed to incorporate BPH resistance genes from the donor lines, M229 and 10–3 into TS. Foreground selection using gene-specific SSRs pinned down one plant (BC 1 (a)-19) from TS//TS/M229 cross with qBph-3–1 and Bph33(t) genes/QTLs, while, six plants of TS//TS/10–3 cross had Bph33(t) gene. Validation of BC 1 F 1 plants with designed SNPs altogether identified three (BC 1 (a)-14, BC 1 (a)-18, BC 1 (a)-19) from TS//TS/M229 and three lines (BC 1 (b)-2, BC 1 (b)-4, BC 1 (b)-5) from TS//TS/10–3 cross positive for snpOS00915, snpOS00922 and snpOS00923. All these lines were also found to be phenotypically resistant to BPH as screened using a modified mass tiller screening method. Altogether, foreground selection coupled with stringent phenotypic selection and agro-morphological evaluation led to the identification of two backcross lines (BC 1 (a)-14 and BC 1 (a)-19) from TS//TS/M229 and three (BC 1 (b)-2, BC 1 (b)-4, BC 1 (b)-5) from TS//TS/10–3 that had grain type characteristics similar to TS that can be potentially used as breeding material for further backcrossing and advancing for near isogenic lines development. The study demonstrates the potential efficacy of marker-assisted selection deployed with both SSRs and SNPs that can be employed in breeding for BPH-resistant varieties. [ABSTRACT FROM AUTHOR]

The population growth and the regular breakout of Nilaparvata lugens pose a significant risk to rice cultivation. Four different N. lugens biotypes have been identified worldwide, with biotype 4 being the most destructive and prevalent throughout Asia, particularly in India. Therefore, a rice variety with multiple resistance genes/alleles is required for effective management of N. lugens. Hence, 191 rice genotypes collected from various parts of India were evaluated for resistance to N. lugens. Further, SSR markers representing 23 different N. lugens resistant (R) genes were assayed to identify genomic regions associated with resistance. The results of the genetic analysis showed that the average genetic diversity value of all markers was 0.165 and polymorphic information content of 0.145 for all the markers used. The population structure and cluster analysis divided the studied genotypes into three distinct groups, with resistant genotypes grouped separately. These findings were confirmed by the principal coordinate analysis, which categorized resistant genotypes, moderately resistant genotypes, and susceptible genotypes into distinct components. Additionally, 90% of the genetic variation was between individuals of populations and 10% between the populations. Marker‐trait association study through mixed linear model and generalized linear model identified six SSR markers such as RM6732 (Bph15), RM314 (Bph6), RM16999 (Bph6), RM7 (QBph3), RM401 (bph4), and RM7102 (Bph1), which were significantly associated with various phenotypic parameters, such as feeding mark, honeydew excretion, percent damage and nymphal survival. The resistant genes identified in these genotypes could help in the marker‐assisted rice variety development with durable resistance against N. lugens. [ABSTRACT FROM AUTHOR]

Counting planthoppers manually is laborious and yields inconsistent results, particularly when dealing with species with similar features, such as the brown planthopper (Nilaparvata lugens; BPH), whitebacked planthopper (Sogatella furcifera; WBPH), zigzag leafhopper (Maiestas dorsalis; ZIGZAG), and green leafhopper (Nephotettix malayanus and Nephotettix virescens; GLH). Most of the available automated counting methods are limited to populations of a small density and often do not consider those with a high density, which require more complex solutions due to overlapping objects. Therefore, this research presents a comprehensive assessment of an object detection algorithm specifically developed to precisely detect and quantify planthoppers. It utilises annotated datasets obtained from sticky light traps, comprising 1654 images across four distinct classes of planthoppers and one class of benign insects. The datasets were subjected to data augmentation and utilised to train four convolutional object detection models based on transfer learning. The results indicated that Faster R-CNN VGG 16 outperformed other models, achieving a mean average precision (mAP) score of 97.69% and exhibiting exceptional accuracy in classifying all planthopper categories. The correctness of the model was verified by entomologists, who confirmed a classification and counting accuracy rate of 98.84%. Nevertheless, the model fails to recognise certain samples because of the high density of the population and the significant overlap among them. This research effectively resolved the issue of low- to medium-density samples by achieving very precise and rapid detection and counting. [ABSTRACT FROM AUTHOR]

BACKGROUND: The brown planthopper (BPH), Nilaparvata lugens, is one of the most destructive pests of rice. Owing to the rapid adaptation of BPH to many pesticides and resistant varieties, identifying putative gene targets for developing RNA interference (RNAi)‐based pest management strategies has received much attention for this pest. The glucoprotein papilin is the most abundant component in the basement membranes of many organisms, and its function is closely linked to development. RESULTS: In this study, we identified a papilin homologous gene in BPH (NlPpn). Quantitative Real‐time PCR analysis showed that the transcript of NlPpn was highly accumulated in the egg stage. RNAi of NlPpn in newly emerged BPH females caused nonhatching phenotypes of their eggs, which may be a consequence of the maldevelopment of their embryos. Moreover, the transcriptomic analysis identified 583 differentially expressed genes between eggs from the dsGFP‐ and dsNlPpn‐treated insects. Among them, the 'structural constituent of cuticle' cluster ranked first among the top 15 enriched GO terms. Consistently, ultrastructural analysis unveiled that dsNlPpn‐treated eggs displayed a discrete and distorted serosal endocuticle lamellar structure. Furthermore, the hatchability of BPH eggs was also successfully reduced by the topical application of NlPpn‐dsRNA‐layered double hydroxide nanosheets onto the adults. CONCLUSION: Our findings demonstrate that NlPpn is essential to maintaining the regular structure of the serosal cuticle and the embryonic development in BPH, indicating NlPpn could be a potential target for pest control during the egg stage. © 2024 Society of Chemical 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]

BACKGROUND: Saliva has a crucial role in determining the compatibility between piercing–sucking insects and their hosts. The brown planthopper (BPH) Nilaparvata lugens, a notorious pest of rice in East and Southeast Asia, secretes gelling and watery saliva when feeding on rice sap. Nlsalivap‐5 (NlSP5) and Nlsalivap‐7 (NlSP7) were identified as potential planthopper‐specific gelling saliva components, but their biological functions remain unknown. RESULTS: Here, we showed by transcriptomic analyses that NlSP5 and NlSP7 were biasedly expressed in the salivary glands of BPHs. Using the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9‐mediated genome‐editing system, we constructed NlSP5 and NlSP7 homozygous mutants (NlSP5−/− and NlSP7−/−). Electrical penetration graph assay showed that NlSP5−/− and NlSP7−/− mutants exhibited abnormal probing and feeding behaviors. Bioassays revealed that the loss‐of‐function of NlSP5 and NlSP7 significantly reduced the fitness of BPHs, with extended developmental duration, shortened lifespan, reduced weight, and impaired fecundity and hatching rates. CONCLUSION: These findings deepen our understanding of the BPH–host interaction and may provide potential targets for the management of rice planthoppers. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Brown planthopper (BPH), Nilaparvata lugens (Stal) is a monophagous and one of most devastating pest of rice. Application of insecticides is inevitable to control the infestation of BPH on rice crops. However, the indiscriminate use of various insecticides in rice is leading to pest resurgence. Several factors have been connected to the resurgence of brown planthoppers, especially the reduction in natural enemies and changes in plant nutrition after insecticide application. Hence, in the present study, we studied the resurgence of BPH post application of different insecticides in rice and assessed the impact of insecticides on natural enemy population during Rabi 2022-23. Among nine insecticides tested, two insecticides viz., deltamethrin 11 EC @ 15 g a.i/ha (44.70%) and imidacloprid 17.8 SL @ 25 g a.i/ha (23.01%) significantly increased the population of N. lugens over untreated check and consequently resulted in higher BPH resurgence. A greater reduction in predatory mirid bugs and spiders was observed in the deltamethrin and imidacloprid treated groups compared to the untreated check. In conclusion, we found that deltamethrin and imidacloprid induce the BPH resurgence in rice compared to other tested insecticides and the observed resurgence was partly due to the reduction of natural enemies. [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]

The brown planthopper (BPH, Nilaparvata lugens) is a notorious sap‐sucking insect pest that damages rice (Oryza sativa) plants throughout Asia. During BPH feeding, saliva enters rice plant tissues, whereas during oviposition egg‐associated secretions (EAS) are deposited in damaged plant tissue. Dynamic changes in rice to planthopper salivary effectors have been widely reported. However, the effects of EAS from planthopper on rice immunity remains largely unexplored. In this study, we found that both infestation of rice by gravid BPH female adults and treatment with the EAS elicited a strong and rapid accumulation of jasmonic acid (JA), JA‐isoleucine, and hydrogen peroxide in rice. EAS enhanced plant defenses not only in rice but also in tobacco, and these impaired the performance of BPH on rice, as well as the performance of aphids and whiteflies on tobacco. High‐throughput proteome sequencing of EAS led to 110 proteins being identified and 53 proteins with 2 or more unique peptides being detected. Some proteins from BPH EAS were also found in the salivary proteome from herbivores, suggesting potential evolutionary conservation of effector functions across feeding and oviposition; however, others were only identified in EAS, and these are likely specifically related to oviposition. These findings point to novel proteins affecting interactions between planthoppers and rice during oviposition, providing an additional source of information for effector studies. [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]

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

Fatty acyl‐CoA reductase (FAR) is one of the key enzymes, which catalyses the conversion of fatty acyl‐CoA to the corresponding alcohols. Among the FAR family members in the brown planthopper (Nilaparvata lugens), NlFAR7 plays a pivotal role in both the synthesis of cuticular hydrocarbons and the waterproofing of the cuticle. However, the precise mechanism by which NlFAR7 influences the formation of the cuticle structure in N. lugens remains unclear. Therefore, this paper aims to investigate the impact of NlFAR7 through RNA interference, transmission electron microscope, focused ion beam scanning electron microscopy (FIB‐SEM) and lipidomics analysis. FIB‐SEM is employed to reconstruct the three‐dimensional (3D) architecture of the pore canals and related cuticle structures in N. lugens subjected to dsNlFAR7 and dsGFP treatments, enabling a comprehensive assessment of changes in the cuticle structures. The results reveal a reduction in the thickness of the cuticle and disruptions in the spiral structure of pore canals, accompanied by widened base and middle diameters. Furthermore, the lipidomics comparison analysis between dsNlFAR7‐ and dsGFP‐treated N. lugens demonstrated that there were 25 metabolites involved in cuticular lipid layer synthesis, including 7 triacylglycerols (TGs), 5 phosphatidylcholines (PCs), 3 phosphatidylethanolamines (PEs) and 2 diacylglycerols (DGs) decreased, and 4 triacylglycerols (TGs) and 4 PEs increased. In conclusion, silencing NlFAR7 disrupts the synthesis of overall lipids and destroys the cuticular pore canals and related structures, thereby disrupting the secretion of cuticular lipids, thus affecting the cuticular waterproofing of N. lugens. These findings give significant attention with reference to further biochemical researches on the substrate specificity of FAR protein, and the molecular regulation mechanisms during N. lugens life cycle. [ABSTRACT FROM AUTHOR]

Insect transient receptor potential vanilloid (TRPV) channels serve as important targets for pyridine azomethine insecticides, playing crucial roles in sustainable pest management. In this study, the homology model of Nilaparvata lugens TRPV, a heterotetramer comprising the Nanchung and Inactive subunits, was constructed using the crystal structures of rabbit TRPV5 and human TRPV6 as templates. The potential binding site and binding modes between pyridine azomethine insecticides and N. lugens TRPV were further investigated. Our findings revealed that pymetroizne formed T-shaped π–π interaction and H-bonds with the residues Phe688 on the S4 helix, as well as Glu627 on S2, and Ala643 and Arg646 on S3 of the Nanchung subunit, respectively. A hierarchical virtual screening protocol was then used to identify a potential insect TRPV channel modulator A6 with a novel phenylhydrazidoyl scaffold, and the chemical optimization of this scaffold led to the discovery of compound B4 with 68.7% mortality rate against Aphis craccivora at 200.0 mg L−1. These findings lay a foundation not only for exploring the mechanisms of action of pymetrozine, but also for developing new insecticides targeting the TRPV channels of pests. [ABSTRACT FROM AUTHOR]

Introduction: Akirin as a highly conserved transcription factor, exerts a profound influence on the growth, development, immune response, and reproductive processes in animals. The brown planthopper (BPH), Nilaparvata lugens, a major pest in rice production in Asia, possesses high reproductive capacity, a critical factor contributing to reduced rice yields. The aims of this study were to demonstrate the regulatory role of Akirin in the reproduction of BPH. Methods: In this study, quantitative PCR (qPCR) was used to detect the mRNA expression of genes. RNA interference (RNAi) was used to downregulate the expression of Akirin gene, and RNA sequencing (RNA-seq) was used to screen for differentially expressed genes caused by Akirin downregulation. Hormone contents were measured with the enzyme linked immunosorbent assay (ELISA), and protein content was evaluated with the bicinchoninic acid (BCA) method. Results: Using BPH genome data, we screened for an Akirin gene (NlAkirin). An analysis of tissue-specific expressions showed that NlAkirin was expressed in all tissues tested in female BPH, but its expression level was highest in the ovary. After inhibiting the mRNA expression of NlAkirin in BPH females, the number of eggs laid, hatching rate, and number of ovarioles decreased. Transcriptome sequencing was performed, following a NlAkirin double-stranded RNA treatment. Compared with the genes of the control, which was injected with GFP double-stranded RNA, there were 438 upregulated genes and 1012 downregulated genes; the expression of vitellogenin (Vg) and vitellogenin receptor (VgR) genes as well as the mRNA expression of genes related to the target of rapamycin (TOR), juvenile hormone (JH), and insulin pathways involved in Vg synthesis was significantly downregulated. As a result of NlAkirin knockdown, the titers of JH III and Ecdysone (Ecd) were downregulated in unmated females but returned to normal levels in mated females. The ovarian protein contents in both unmated and mated females were downregulated. Discussion and conclusion: Our results suggest that NlAkirin affects female BPH reproduction by regulating the mRNA expression of genes related to the Vg, VgR, TOR, JH, and insulin signaling pathways, in addition to the titers of JH III and Ecd. The findings of this research provide novel insights into the regulatory role of Akirin in insect reproductive capacity. [ABSTRACT FROM AUTHOR]

We made separate experiments to examine life‐history traits and activities of protective enzymes as affected by carbon dioxide (CO2) elevation to 780 μL/L as compared to 390 μL/L in imidacloprid‐ or buprofezin‐resistant strains of the brown planthopper (BPH) Nilaparvata lugens. We found an interaction effect between resistance and the CO2 level on the nymphal survival and duration in both resistant strains. Nymphal durations in both resistant strains were much shorter in the resistant than susceptible BPH at 780 μL/L but similar between them or slightly shorter in the resistant than susceptible BPH at 390 μL/L. Nymphal survival was lower for imidacloprid‐resistant than its susceptible BPH at 390 μL/L but higher at 780 μL/L; it stayed unaffected by the CO2 elevation in buprofezin‐resistant BPH. We did not observe an interaction effect between resistance and the CO2 level on major reproductive parameters in both resistant strains. But the 2 strains were not consistent across CO2 levels in all parameters. Our measurements of protective enzyme activities of superoxide dismutase, catalase, and peroxidase showed an interaction between resistance and the CO2 level. Overall, these enzymes became similar in activity between resistant and susceptible BPH at 780 μL/L compared to 390 μL/L and the change was more distinct in the imidacloprid‐ than buprofezin‐resistant BPH strains. Our findings suggest that CO2 elevation can affect life‐history traits of insecticide‐resistant BPH, while the effect may vary depending on the kind of insecticides it is resistant to. [ABSTRACT FROM AUTHOR]

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

Wing dimorphism in Nilaparvata lugens is controlled by the insulin‐like growth factor 1 (IGF‐1) signaling – Forkhead transcription factors (IIS‐FoxO) pathway. However, the role of this signal in the wing development program remains largely unclear. Here, we identified 2 R‐SMAD proteins, NlMAD1 and NlMAD2, in the brown planthopper (BPH) transcriptome, derived from the intrinsic transforming growth factor‐β pathway of insect wing development. Both proteins share high sequence similarity and conserved domains. Phylogenetic analysis placed them in the R‐SMAD group and revealed related insect orthologs. The expression of Nlmad1 was elevated in the late instar stages of the macropterous BPH strain. Nlmad1 knockdown in nymphs results in malformed wings and reduced wing size in adults, which affects the forewing membrane. By contrast, Nlmad2 expression was relatively consistent across BPH strains and different developmental stages. Nlmad2 knockdown had a milder effect on wing morphology and mainly affected forewing veins and cuticle thickness in the brachypterous strain. NlMAD1 functions downstream of the IIS‐FoxO pathway by mediating the FoxO‐regulated vestigial transcription and wing morph switching. Inhibiting Nlmad1 partially reversed the long‐winged phenotype caused by NlFoxO knockdown. These findings indicate that NlMAD1 and NlMAD2 play distinct roles in regulating wing development and morph differentiation in BPH. Generally, NlMAD1 is a key mediator of the IIS‐FoxO pathway in wing morph switching. [ABSTRACT FROM AUTHOR]

Simple Summary: The brown planthopper, Nilaparvata lugens, is a destructive insect pest that poses a serious threat to rice production. Because the brown planthopper is a phloem-sap-feeding insect and relies on sugars as their main source of carbon, sugar transporters are particularly important. We identified 34 sugar transporters in N. lugens (NlSTs) and inferred their possible function based on their expression patterns. We identified a number of NlST genes that are expressed at higher levels in the gut than in other tissues, such as NlST2, 3, 4, 7, 20, 27, 28, and 31. This study provides a basis for further exploring the function of NlST genes in brown planthopper. Sugar transporters play important roles in controlling carbohydrate transport and are responsible for mediating the movement of sugars into cells in numerous organisms. In insects, sugar transporters not only play a role in sugar transport but may also act as receptors for virus entry and the accumulation of plant defense compounds. The brown planthopper, Nilaparvata lugens, inflicts damage on rice plants by feeding on their phloem sap, which is rich in sugars. In the present study, we identified 34 sugar transporters in N. lugens, which were classified into three subfamilies based on phylogenetic analysis. The motif numbers varied from seven to eleven, and motifs 2, 3, and 4 were identified in the functional domains of all 34 NlST proteins. Chromosome 1 was found to possess the highest number of NlST genes, harboring 15. The gut, salivary glands, fat body, and ovary were the different tissues enriched with NlST gene expression. The expression levels of NlST2, 3, 4, 7, 20, 27, 28, and 31 were higher in the gut than in the other tissues. When expressed in a Saccharomyces cerevisiae hexose transporter deletion mutant (strain EBY.VW4000), only ApST4 (previously characterized) and NlST4, 28, and 31 were found to transport glucose and fructose, resulting in functional rescue of the yeast mutant. These results provide valuable data for further studies on sugar transporters in N. lugens and lay a foundation for finding potential targets to control N. lugens. [ABSTRACT FROM AUTHOR]

The brown planthopper (Nilaparvata lugens Stål, BPH) is the most destructive pest of rice (Oryza sativa L.). Utilizing resistant rice cultivars that harbor resistance gene/s is an effective strategy for integrated pest management. Due to the co-evolution of BPH and rice, a single resistance gene may fail because of changes in the virulent BPH population. Thus, it is urgent to explore and map novel BPH resistance genes in rice germplasm. Previously, an indica landrace from India, Paedai kalibungga (PK), demonstrated high resistance to BPH in both in Wuhan and Fuzhou, China. To map BPH resistance genes from PK, a BC1F2:3 population derived from crosses of PK and a susceptible parent, Zhenshan 97 (ZS97), was developed and evaluated for BPH resistance. A novel BPH resistance locus, BPH39, was mapped on the short arm of rice chromosome 6 using next-generation sequencing-based bulked segregant analysis (BSA-seq). BPH39 was validated using flanking markers within the locus. Furthermore, near-isogenic lines carrying BPH39 (NIL-BPH39) were developed in the ZS97 background. NIL-BPH39 exhibited the physiological mechanisms of antibiosis and preference toward BPH. BPH39 was finally delimited to an interval of 84 Kb ranging from 1.07 to 1.15 Mb. Six candidate genes were identified in this region. Two of them (LOC_Os06g02930 and LOC_Os06g03030) encode proteins with a similar short consensus repeat (SCR) domain, which displayed many variations leading to amino acid substitutions and showed higher expression levels in NIL-BPH39. Thus, these two genes are considered reliable candidate genes for BPH39. Additionally, transcriptome sequencing, DEGs analysis, and gene RT-qPCR verification preliminary revealed that BPH39 may be involved in the jasmonic acid (JA) signaling pathway, thus mediating the molecular mechanism of BPH resistance. This work will facilitate map-based cloning and marker-assisted selection for the locus in breeding programs targeting BPH resistance. [ABSTRACT FROM AUTHOR]

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