Lugens Populations Research Articles

Identification of a vital transcription factor of the alanine aminotransferase in the brown planthopper and its upstream regulatory pathways

The brown planthopper (Nilaparvata lugens) is an important insect pest of rice, and can rapidly adapt to insect-resistant rice varieties. In our previous studies, alanine aminotransferase in N. lugens (NlALT) was found to play an important role in the adaptation of the brown planthopper to resistant rice IR36. Here, we further identified CCAAT/enhancer binding protein (NlC/EBP) as a vital transcription factor of NlALT. Nlp38b in the MAPKs pathway regulated the expression of NlALT by influencing the phosphorylation level of NlC/EBP. In addition, we found that NlGRL101, a G protein-coupled receptor (GPCR), was significantly higher expressed in the N. lugens population adapted to IR36 (P-IR36). After knockdown of NlGRL101 through RNAi in P-IR36 population, lower expressions of Nlp38b and NlC/EBP, along with reduced phosphorylation levels of Nlp38b and NlC/EBP were observed; moreover, NlALT activity and honeydew amount were decreased by 15.68% and 76.08%, respectively. These results indicated that insect-resistant rice IR36 induced expression of NlGRL101, which enhanced expression of NlALT through Nlp38b and NlC/EBP. These findings are helpful for better understanding of insect adaptation to resistant crop varieties.

Tendency to mate with short-winged partner of the brown planthopper Nilaparvata lugens (Hemiptera: Delphacidae).

Wing dimorphism is a distinguishing characteristic of brown planthopper Nilaparvata lugens (Stål) populations, wherein adults exhibit 2 distinct morphs: long-winged and short-winged. The presence of long-winged individuals often heralds the onset of migration, while short-winged morphs signify high reproduction and can be associated with population outbreaks. This phenomenon underscores the adaptability of these insects in response to environmental cues and their impact on agricultural ecosystems. Wing morphs of N. lugens are controlled by genetical and environmental factors. Mate choice between long and short-winged adults affects wing morphs of offspring. In this study, we found that the wild population had no persistent preference for choosing long-winged or short-winged adults to mate. But in 2 multigenerational selected lineages for long and short-winged morphs, the short-winged males preferred to short-winged females to mate and the long-winged males had no preference. In the nearly pure-bred lineages of long-winged and short-winged morphs, both wing morphs of females preferred for short-winged males. Purification of wing morph lineages enhanced mating preference for short-winged partners. When the wing developmental gene InR1 or InR2 was interfered by RNAi, the pure-bred lineage of long-winged morph mainly produced short-winged adults and the short-winged morphs produced long-winged adults, and these adults exhibited preference to mate with short-winged partners. The tendency to mate with short-winged morphs leads to more short-winged offspring which easily causes the rapid growth of populations.

Rice brown planthopper, Nilaparvata lugens (Stål) feeding behavior in relation to elevated CO2 and temperature

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

The Jinggangmycin-induced Mthl2 gene regulates the development and stress resistance in Nilaparvata lugens Stål (Hemiptera: Delphacidae)

Methuselah (Mth) belongs to the GPCR family B, which regulates various biological processes and stress responses. The previous transcriptome data showed jinggangmycin (JGM)-induced Mthl2 expression. However, its detailed functional role remained unclear in brown planthopper, Nilaparvata lugens Stål. In adult N. lugens, the Mthl2 gene showed dominant expressions, notably in ovaries and fat body tissues. The 3rd instar nymphs treated with JGM increased starvation, oxidative stress, and high temperature (34 °C) tolerance of the adults. On the contrary, under dsMthl2 treatment, completely opposite phenotypes were observed. The lipid synthesis genes (DGAT1and PNPLA3) of both females and males treated with JGM in the nymphal stage were observed with high expressions, while the lipolysis of the Lipase 3 gene was observed with low expressions. The JGM increased triglyceride (TG) content, fat body droplet size, and the number of fat body droplets. The same treatment also increased the Glutathione S-transferase (GST), catalase (CAT), and superoxide dismutase (SOD) activities. An increase in the heat shock protein (HSP70 and HSP90) expression levels was also observed under JGM treatment but not dsMthl2. The current study demonstrated the influential role of the Mthl genes, particularly the Mthl2 gene, in modulating the growth and development and stress-responsiveness in N. lugens. Thus, providing a platform for future applied research programs controlling N. lugens population in rice fields.

The Fall Armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), Influences Nilaparvata lugens Population Growth Directly, by Preying on Its Eggs, and Indirectly, by Inducing Defenses in Rice.

The fall armyworm (FAW), Spodoptera frugiperda, has become one of the most important pests on corn in China since it invaded in 2019. Although FAW has not been reported to cause widespread damage to rice plants in China, it has been sporadically found feeding in the field. If FAW infests rice in China, the fitness of other insect pests on rice may be influenced. However, how FAW and other insect pests on rice interact remains unknown. In this study, we found that the infestation of FAW larvae on rice plants prolonged the developmental duration of the brown planthopper (BPH, Nilaparvata lugens (Stål)) eggs and plants damaged by gravid BPH females did not induce defenses that influenced the growth of FAW larvae. Moreover, co-infestation by FAW larvae on rice plants did not influence the attractiveness of volatiles emitted from BPH-infested plants to Anagrus nilaparvatae, an egg parasitoid of rice planthoppers. FAW larvae were able to prey on BPH eggs laid on rice plants and grew faster compared to those larvae that lacked available eggs. Studies revealed that the delay in the development of BPH eggs on FAW-infested plants was probably related to the increase in levels of jasmonoyl-isoleucine, abscisic acid and the defensive compounds in the rice leaf sheaths on which BPH eggs were laid. These findings indicate that, if FAW invades rice plants in China, the population density of BPH may be decreased by intraguild predation and induced plant defenses, whereas the population density of FAW may be increased.

Resistance Monitoring of Nilaparvata lugens to Pymetrozine Based on Reproductive Behavior

On the basis of the inhibition effects of pymetrozine on the reproductive behavior of N. lugens, we established a bioassay method to accurately evaluate the toxicity of pymetrozine in N. lugens and clarified the level of pymetrozine resistance of N. lugens in the field. In this study, pymetrozine's effects on the fecundity of N. lugens were evaluated using the topical application method and rice-seedling-dipping method. Moreover, the resistance of N. lugens to pymetrozine in a pymetrozine-resistant strain (Pym-R) and two field populations (YZ21 and QS21) was determined using the rice-seedling-dipping method and fecundity assay methods. The results showed that treatment of N. lugens third-instar nymphs with LC15, LC50, and LC85 doses of pymetrozine resulted in a significantly reduced fecundity of N. lugens. In addition, N. lugens adults treated with pymetrozine, using the rice-seedling-dipping and topical application method, also exhibited a significantly inhibited fecundity. Using the rice-stem-dipping method, pymetrozine resistance levels were shown to be high in Pym-R (194.6-fold), YZ21 (205.9-fold), and QS21 (212.8-fold), with LC50 values of 522.520 mg/L (Pym-R), 552.962 mg/L (YZ21), and 571.315 (QS21) mg/L. However, when using the rice-seedling-dipping or topical application fecundity assay method, Pym-R (EC50: 14.370 mg/L, RR = 12.4-fold; ED50: 0.560 ng/adult, RR = 10.8-fold), YZ21 (EC50: 12.890 mg/L, RR = 11.2-fold; ED50: 0.280 ng/adult; RR = 5.4-fold), and QS21 (EC50: 13.700 mg/L, RR = 11.9-fold) exhibited moderate or low levels of resistance to pymetrozine. Our studies show that pymetrozine can significantly inhibit the fecundity of N. lugens. The fecundity assay results showed that N. lugens only developed low to moderate levels of resistance to pymetrozine, indicating that pymetrozine can still achieve effective control on the next generation of N. lugens populations.

Communal rearing induces high predatory capacity in a solitary wolf spider and its potential in pest control.

Behavioral plasticity is of great significance because it allows individuals to flexibly respond to variations in the ecological and social environment. To date, there is little published data on the topic of whether the early rearing experience of spiders influences their later foraging behavior. Pardosa pseudoannulata (Araneae: Lycosidae) is a solitary wolf spider, it is a major predator of pests such as Nilaparvata lugens in rice fields. In this study, we aim to develop a communal rearing protocol for spiders. We conducted a rearing study in the lab that one group of wolf spiders was reared communally and a second group was reared individually. We compared the survival rates and predatory capacity of P. pseudoannulata in both settings. Survival rates were similar overall. At forty-five days, survival rates were below 40% for both groups. Raising spiders communally led to higher foraging levels. Across all tested time points, spiders reared communally hunted more fruit flies than those reared individually. Significant differences were found between the two rearing groups after hunting for seven and 10 min. Field experiment showed that release of communal-reared spiders significantly reduced the pest N. lugens population. Our research provides reference for the large-scale breeding of spiders and their application as biological control agents.

Genetic Differentiation of Brown Planthopper Nilaparvata lugens (Stål) Populations in Asia

Brown Planthopper is one of the economically important rice pests that cause several crop failures in Asian countries. Unfortunately, Brown Planthopper could migrate to neighboring countries to generate interpopulation breeding, thus further increasing the gene flow and spreading insecticide resistance. This research aimed to understand the genetic differentiation of Brown Planthopper among all Asian populations. This study used two COI sequences from Malang, Indonesia, and 25 sequences from GenBank to analyze the genetic structure with phylogenetic tree and haplotype network. The uncorrected pairwise distance result showed that the Brown Planthopper population in Asia has a relatively low genetic distance. We also found that the Brown Planthopper population was clustered based on the geographical region of South Asia, East Asia-Mainland South East Asia, and Indonesia. Thus, we concluded that the migration of Brown Planthopper was limited to East Asia and Mainland South East Asia only. Further studies are needed to confirm the migration route of Brown Planthopper in South Asia and Southeast AsiaKeywords: BPH, Genetic differentiation, Haplotype network, Phylogenetic

Status of insecticide resistance in rice brown planthopper (Nilaparvata lugens) in Punjab

The present study was undertaken in 2017–18 at the entomological Research Farm, PAU, Ludhiana to determine the status of insecticide resistance and the role of enzymes in imparting resistance in Nilaparvata lugens. Toxicity of insecticides, viz. imidacloprid, chlorpyriphos, quinalphos, buprofezin and lambda cyhalothrin against the susceptible and field populations of N. lugens were evaluated. Based on LC50 values calculated, the susceptible population showed the highest sensitivity to buprofezin with lowest LC50 value of 0.0007% while the lowest sensitivity was observed for chlorpyriphos (0.0010%). Buprofezin proved most effective against planthopper population collected from Ludhiana and Patiala with LC50 values of 0.0032% and 0.0036% and toxicity ratios of 4.40 and 2.75, respectively, whereas quinalphos proved effective against Kapurthala population with LC50 value of 0.0027% and toxicity ratio of 2.85. Imidacloprid was the least effective insecticide at all test locations (LC50 values ranged from 0.0077% to 0.0141%). N. lugens population showed moderate level of resistance development to imidacloprid at all the test locations, viz. 19.09-folds in Ludhiana, 14.14-folds in Patiala and 11-folds resistance in Kapurthala. The resistance ratio for buprofezin was the lowest (4.57-folds) in case of Ludhiana population, whereas in case of Patiala and Kapurthala populations, resistance to quinalphos was the lowest (4.39 and 3.00-folds, respectively). The activity of esterases was significantly higher in the field populations collected from Ludhiana whereas the activities of acetylcholinesterase in resistant populations of Ludhiana and Patiala were significantly higher than in the susceptible population, indicating their probable role in imparting resistance.

Resistance of Nilaparvata lugens to Fenobucarb and Imidacloprid and Susceptibility to Neem Oil Insecticides

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

SRAP analysis of brown planthopper (Nilaparvata lugens) populations maintained on differential rice host varieties

Abstract. Chaerani, Dadang A, Fatimah, Husin BA, Sutrisno, Yunus M. 2021. SRAP analysis of brown planthopper (Nilaparvata lugens) populations maintained on differential rice host varieties. Biodiversitas 22: 4266-4272. Brown planthopper (Nilaparvata lugens Stål) biotypes differ in virulence to rice varieties carrying different Bph resistance genes. These biotypes are reported can be genetically discriminated against using DNA markers. Four brown planthoppers (BPH) populations, which displayed two virulence phenotypes, have been produced by selection and adaptation on four differential host varieties. Sequence-related amplified polymorphism (SRAP) marker preferentially amplifies the coding regions in the genome and, thus, can discriminate the observed virulence variations among those populations. This study aimed to analyze the genetic variation of four developed BPH populations using SRAP markers. Genetic analysis of a total of 40 BPH females with 18 polymorphic primers revealed equal genetic diversity parameter values among populations (Na: 1.1 to 1.4, Ne: 1.2 to 1.3, I: 0.22 to 0.29, He: 0.14 to 0.18, and UHe: 0.15 to 0.19). Analysis of population structure by AMOVA indicated low genetic variation among populations (9%). Still, pairwise PhiPT population values between all pairs of the population revealed the presence of moderate genetic differentiations (PhiPT ranged from 0.57 to 0.133, P<0.01). Two partial clusters in plots of PCoA were corresponded to two virulence groups, indicating the ability of SRAP markers to discriminate virulence phenotype. Further selection and adaptation are expected can form four desired virulence patterns with complete genetic separation among the population before its application as resistance screening agents of rice lines.

Current resistance status of the brown planthopper Nilaparvata lugens (Stål) to commonly used insecticides in China and Bangladesh

Nilaparvata lugens (Stål) is a serious threat to rice production in Asian countries. Synthetic chemicals are widely used for its control. However, evolution of resistance in this pest to commonly used insecticides has been recorded during the last decades. In this study, we determined and compared current insecticide resistance levels of thirteen N. lugens populations from China and Bangladesh to eight insecticides by rice-stem dipping method. These results showed that N. lugens had developed high levels of resistance to imidacloprid (resistance ratio, RR = 2491.0–8078.5-fold), thiamethoxam (RR = 303.6–1253.6-fold), buprofezin (RR = 175.7–365.1-fold) and dinotefuran (RR = 49.9–596.0-fold), low to moderate levels of resistance to nitenpyram (RR = 12.1–67.3-fold) and sulfoxaflor (RR = 3.8–25.5-fold), but were susceptible to triflumezopyrim (RR = 0.2–1.1-fold) in China. Meanwhile, increased activities of detoxification enzymes (EST, GST and P450) were found in multiple-resistant FY19 field population, which also showed the significant changes in the expression levels of P450s compared to susceptible strain, especially CYP6ER1 (11.04-fold). In contrast, first report of insecticide resistance in Bangladesh showed high levels of resistance to imidacloprid (RR = 3680.1–4430.8-fold) and thiamethoxam (RR = 144.3–737.9-fold), low to moderate levels of resistance to dinotefuran (RR = 38.7–57.9-fold), buprofezin (RR = 28.5–149.1-fold) and nitenpyram (RR = 3.4–14.1-fold). In addition, significant differences in insecticide resistance level of N. lugens to nitenpyram and dinotefuran were observed between two countries in 2020. The present study will be beneficial for implementing effective resistance management strategies to prevent or delay resistance development in N. lugens.

Resistance Monitoring of Nilaparvata lugens Stall against Pymetrozine Insecticide with Determination of Diagnostic Concentrations

Nilaparvata lugens Stall is one of the main insect pests on rice crops. Intensive control of this pests using insecticides has resulted in the development of insect resistance. This study aimed to find out the level of resistance of the N. lugens population to pymetrozine insecticides by determining the diagnostic concertations. N. lugens was collected from five endemic areas in Central Java Province from October 2019 to June 2020. The data from the bioassay test were analyzed with probit analysis to obtain the LC50 value. The results of the sensitivity test showed that the Kajen population has the highest RF value (2.47), while the Karanganyar population which has the lowest RF value (1) was the most sensitive population. The determined diagnostic concentration was LC95 = 25.52 ppm with the lowest concentration limit of 7.67 ppm and the highest of 30.05 ppm. To conclude, the determined diagnostic concentration (LC95 = 25.52 ppm) is effective for detecting the susceptibililty of N. lugens population. This finding would be beneficial for monitoring resistance of N. lugens population against pymetrozine insecticides in the field.

The performance of the brown planthopper (Nilaparvata lugens) population and predators on endemic lowland rice areas of Banten Province

Brown planthopper (BPH) are one of the main pests of rice plants, their abundance is influenced by biotic and abiotic factors such as the presence of predators (natural enemies). The aim of the study was to determine the relationship between the natural enemies’ performance and the BPH performance. The study was conducted in BPH endemic areas in Serang and Lebak Regencies from March to July 2017. Sampling was carried out directly through visual observations based on four replications, where each replication consisted of 10 observation units. Data were analyzed descriptively in the form of tables and graphs, BPH performance was calculated based on existing population and corrected population. While predators are calculated based on the exsiting population that at the time of observation. Observations were made for five weeks, from 21 days after planting (DAP) to 56 DAP. The BPH population performance in Serang Regency was highest at 42 DAP (8.05 individual/clump) and in Lebak Regency at 35 DAP (25.05 individual/clump). Paederus is a predator with the highest abundance in Serang District, while the highest abundance of predators in Lebak Regency is spiders.

Genetic dissection and identification of candidate genes for brown planthopper, Nilaparvata lugens (Delphacidae: Hemiptera) resistance in farmers’ varieties of rice in Odisha

Globally, rice production is severely affected by brown planthopper (Nilaparvata lugens) populations. Among the four different biotypes of N. lugens reported worldwide, biotype 4 is the most damaging and prevalent insect pest in South East Asian countries, especially in the Indian sub-continent. Management of this pest with resistant genotypes is effective and thus it has received considerable attention worldwide. In the present work, a total of 600 farmer's varieties (FVs) were screened against N. lugens and subsequently 104 panel populations were selected for genotyping. Marker-trait association and genetic diversity were worked out for 87 molecular markers linked to 34 different N. lugens resistance genes. The average content of polymorphism information was 0.354 for 34 genes with a threshold level 0.018 to 0.750. One hundred and four FVs were categorized into three main genetic groups according to cluster analysis and population structure. Resistant and moderately resistant FVs were separately distributed according to principal co-ordinate analysis. Analysis of molecular variance displayed maximum diversity (83%) within population and minimum diversity (17%) between populations. In both generalized linear model (GLM) and multi linear model (MLM), eight markers linked to Bph genes were found to be common for four different phenotypic parameters like honeydew excretion, nymphal survival, percent damage, and feeding mark. Our study suggests that presently available monogenic BPH resistant lines were not withstanding BPH biotype-4 pressure. Thus, the reported resistance genes either alone or in combination could be introgressed into elite varieties with genomic approach to develop robust resistant rice varieties against N. lugens biotype 4. Further, the identified FVs are useful for novel R genes identification, host–insect interaction, and genomic studies.

Effect of Anredera cordifolia (Ten) Steenis Leaves Ethanol Extract in suppressing Brown PlantHopper (Nilaparvata lugens Stal.) Populations on Rice Plant

The Brown Planthopper (Nilaparvata lugens Stal.) is one of the pests that often causes rice crop failure in rice. One way to control N. lugens pests is to use of botanical insecticide. The purpose of this experiment is to study the effect of A. cordifolia leaves ethanol in suppressing N. lugens populations. The experiment used a Randomized Block Design (RDB) with 8 treatments and 4 replications. The A. cordifolia leaves ethanol extract concentration tested in this experiment consisted of 0,5%; 0,75%; 1%; 1,5%; and 2%. The results of the experiment showed that the ethanol extract of binahong leaves with a concentration of 1%, 1.5% and 2% cause mortality of N. lugens by 52.50%, 56.25%, and 61.25% on the 14th day after application. Based on the results of this experiment, the ethanol extract of A.cordifolia leaves was not effective against N. lugen.

Sustainable control of the rice pest, Nilaparvata lugens, using the entomopathogenic fungus Isaria javanica.

The brown planthopper (Nilaparvata lugens) is an insect pest of rice (Oryza sativa) that is distributed worldwide and is responsible for significant crop yield losses. Of particular concern, N. lugens has developed high resistance to several commonly used insecticides. The entomopathogenic fungus, Isaria javanica, offers an alternative to insecticides for the control of rice plant pests. We show that I. javanica caused high mortality of N. lugens nymphs and reduced the survival and fecundity of newly emerged adults in I. javanica-treated insects. I. javanica persisted on plants up to 17 days after its inoculation under greenhouse conditions carried out in summer and autumn. Rice metabolites supported conidial germination and mycelia growth of I. javanica. A granular formulation of I. javanica conidia controlled N. lugens populations in a field experiment. The granular formulation promoted fungal survival and growth in the field up to 28 days post inoculation, resulting in increased fungal persistence and greater pest control coverage. These data indicate that a granular formulation of I. javanica is able to control N. lugens populations in rice fields. Therefore, this granular formulation can be an alternative to insecticides and can be used in organic fields. © 2020 Society of Chemical Industry.

The Genetic Structure of Nilaparvata lugens (Stal.) in Java Populations

The brown planthopper Nilaparvata lugens (Stal.) causes hopperburn in the rice field. The wing macropterous adults of this insect have capability for long distance flight. We aimed to analyze the genetic structure of six N. lugens populations in Java inferred from the combined COI-COII mitochondrial and ten loci of microsatellites markers. This study found low levels of nucleotides and high levels of haplotype diversity of the planthopper. The demographic test might indicate the genetic bottleneck history of N. lugens population in Java. The genetic diversity analyzed by using microsatellite markers also showed high levels of heterozygosity (Ho>He) that indicated an isolated-breaking effect in the six populations in Java. Moreover, we found a homogenous genetic structure of N. lugens based on pairwise fixation indices (Fst) analyzes that appears to be maintained by high levels of gene flow and showed no correlation between genetic and geographical distance. Importantly, these studies also support accurate information of widely distributed and genetically intermixed among N. lugens across Asia populations. Thus, our results support the theory of long-distance migration among N. lugenspopulations. The genetic structure information of N. lugens in Java could support regional management, such as the new controlling strategies based on forecasting systems.

NADPH Oxidase 5 Is Essential for Molting and Oviposition in a Rice Planthopper Nilaparvata lugens.

Simple SummaryThe brown planthopper, Nilaparvata lugens, a plant phloem-sucking Hemipteran insect, has become the most destructive pest for rice—the major food source for half of the world’s population. Nilaparvata lugens possess robust fecundity, enabling population densities to increase quickly in a favorable environment. Nilaparvata lugens has also been used as a model system for ecological studies and for developing effective pest management. To better understand the regulation mechanisms of insect reproduction and to provide insights to improve pest control, we searched N. lugens genome and transcriptome databases and identified an NADPH oxidase 5 gene, which was specifically expressed in ovaries of female adults and freshly laid eggs in rice leaf sheaths. Although homologous NADPH oxidase 5 genes have been identified in many insect species, their reproductive functions remain unknown. In this work, our findings initially reveal a functional role of the NADPH oxidase 5 gene in molting and oviposition in N. lugens. This novel finding improves our understanding of the reproductive strategies in insects and provides a potential molecular target for effective pest control of the rice planthopper.The brown planthopper Nilaparvata lugens is a typical monophagous insect herbivore that feeds exclusively on rice sap. This insect pest causes serious damage to rice crops throughout East Asian countries. Chemical control remains the first choice for managing N. lugens populations; however, the use of insecticides has given rise to planthopper resurgence and additional environmental risks. Nilaparvata lugens is a model insect of Hemiptera because its whole genome sequence has been elucidated and is susceptible to RNA interference. In this study, our findings revealed that a superoxide-generating gene, NADPH oxidase 5 (Nox5), is essential for molting and oviposition in a Hemipteran insect Nilaparvata lugens. Knockdown of Nox5 transcript levels by RNA interference in 2nd–5th-instar nymphs results in significantly lethal deficits in the molting transitions from nymph–nymph and nymph–adult. Nox5 knockdown leads to a reduction of hydrogen peroxide in female ovaries and failure of oviposition from the insect ovipositor into the rice leaf sheath. Here, we provide in vivo evidence demonstrating that Nox5 is a key enzyme for regulating molting and oviposition in this insect species.

Comparative iTRAQ proteomic profiling of proteins associated with the adaptation of brown planthopper to moderately resistant vs. susceptible rice varieties.

The brown planthopper (BPH), Nilaparvata lugens (Stål), is a destructive pest that poses a significant threat to rice plants worldwide. To explore how BPHs adapt to the resistant rice variety, we analyzed proteomics profiles of two virulent N. lugens populations. We focused on Biotype Y, which can survive on the moderately resistant rice variety YHY15, and Biotype I, which can survive on the susceptible rice variety TN1. We performed protein quantitation using the isobaric tag for relative and absolute quantification (iTRAQ) and then compared the expression patterns between two virulent N. lugens populations and found 258 differentially expressed proteins (DEPs). We found that 151 of the DEPs were up-regulated, while 107 were down-regulated. We evaluated transcript levels of 8 expressed genes from the iTRAQ results by qRT-PCR, which revealed transcriptional changes that were consistent with the changes at the protein level. The determination of the protein changes in two virulent N. lugens populations would help to better understanding BPH adaptation to resistant rice varieties and facilitate the better design of new control strategies for host defense against BPH.