Genome-wide analysis of Nilaparvata lugens nymphal responses to high-density and low-quality rice hosts

The brown planthopper （BPH） Nilaparvata lugens is an economically impor- tant pest on rice plants. In this study, the higher population density and yellow-ripe stage of rice plants were used to construct adverse survival conditions （ASC） against BPH nymphs. Simultaneously, the low population density and tillering stage of rice plants were used to establish a suitable survival condition （SSC） as a control. Solexa/Illumina sequencing was used to identify genes of BPH nymphs responding to ASC. Significantly longer duration development of BPH nymphs and significantly lower brachypterous ratio of BPH adults were observed by ASC compared with SSC. A total of 2 544 differentially expressed genes （DEGs） were obtained and analyzed by BLASTx, Gene Ontology and KEGG Orthology. Gene ontology analysis revealed that the DEGs were mainly involved in categories of cell, cell part, cellular process, binding, catalytic, organelle and metabolic processes. 1138 DEGs having enzyme commission numbers were assigned to different metabolic pathways. The largest clusters were neurodegenerative diseases （137, 12.0%）, followed by carbohy- drate metabolism （113, 9.9%）, amino acid metabolism （94, 8.3%）, nucleotide metabolism （76, 6.7%）, energy metabolism （64, 5.6%）, translation （60, 5.3%）, lipid metabolism （58, 5.1%）, and folding, sorting and degradation （52, 4.6%）. Expressing profile of 11 DEGs during eight nymphal developmental stages of BPH were analyzed by quantitative real- time polymerase chain reaction. The 11 genes exhibited differential expression between ASC and SSC during at least one developmental stage. The DEGs identified in this study provide molecular proof of how BPH reconfigures its gene expression profile to adapt to overcrowding and low-quality hosts.     

Molecular characterization and gene functional analysis of Dicer‐2 gene from Nilaparvata lugens (Hemiptera: Geometroidea)

Abstract Nilaparvata lugens (Stål) (Hemiptera: Geometroidea), a serious rice pest in many countries of Asia, causes a great loss in rice production every year. RNA interference (RNAi) is a powerful technology for gene function study in insects and a potential tool for pest control. As a core component of RNAi pathway, Dicer‐2 (Dcr‐2) protein determines the production of small interfering RNA (siRNA) and is crucial for the efficiency of RNAi. In this study, the full‐length complementary DNA (cDNA) of N. lugens Dcr‐2 (NlDcr‐2) was first cloned and analyzed, and then the RNAi experiment was conducted to explore the function of NlDcr‐2 gene. The complete Dcr‐2 cDNA of N. lugens was 4 971 bp in length with an open reading frame (ORF) of 1,656 amino acids. Phylogenetic and protein domain analysis showed that the predicted NlDcr‐2 protein was similar to Tribolium castaneum. In the RNAi experiment, the messenger RNA level of NlDcr‐2 was significantly reduced by NlDcr‐2 double‐stranded RNA (dsRNA) (dsDcr‐2). Fifty‐five per cent decrease of NlDcr‐2 was found after 4 days of unremitting feeding. No significant effect was observed on the development of N. lugens after dsRNA ingestion.     

Analysis of differential proteins in two different wing‐types of female Nilaparvata lugens

Nilaparvata lugens (stal) is a rice pest and contains long‐winged and short‐winged varieties, called the wing differentiation. This study compared the protein profiles of the two wing‐types in females and two wing‐disc types 5th‐instar females by two‐dimensional electrophoresis analysis. We detected 172 and 174 protein spots in adults and 5th‐instar nymphs, respectively. The number of proteins with higher content in the long‐winged (disc) individuals is much more than that in the short‐winged (disc) individuals. A total of 32 differential protein spots were found, of which 20 were successfully identified. Their main function is about catabolic process, fiber and nucleoside binding, and they constitute 52 protein–protein interactions, which is around the glycolysis as the core. These results enrich the research on the protein Level in wing development, and provide more references for future studies.     

Enhancement of the geomagnetic field reduces the phototaxis of rice brown planthopper Nilaparvata lugens associated with frataxin down‐regulation

The geomagnetic field (GMF) is an environmental cue that provides directional information for animals. The intensity of GMF is varied over space and time. Variations in the GMF intensity affect the navigation of animals and their physiology. In this study, the phototaxis of the migratory insect rice planthopper Nilaparvata lugens (N. lugens) and frataxin in N. lugens (Nl‐fh), which is a mitochondrial protein required for cellular iron homeostasis and iron‐sulfur cluster assembly, were investigated by using different intensities of magnetic field. From the results, individuals of N. lugens showed decreased phototaxis when reared and tested in a behavioral arena under a strong magnetic field. Besides the reduction in performance, an accompanying effect of the strong magnetic field condition was a reduced level of Nl‐fh‐messenger RNA, and a Nl‐fh knockdown indeed impaired the phototactic behavior in a tested sample of insects. This leads to the conclusion that the expression of frataxin is dependent on the strength of the surrounding magnetic field and that functional frataxin facilitates phototactic behavior in N. lugens.     

褐飞虱表皮蛋白基因NlICP的克隆及功能研究

表皮蛋白与几丁质结合构成抵御外界不良环境的昆虫角质层, 在昆虫的生长发育及蜕皮硬化中具有重要的作用。为了探讨表皮蛋白基因在褐飞虱Nilaparvata lugens生长发育中的功能, 本研究根据褐飞虱转录组测序信息, 对其中1个预测为编码表皮蛋白的Unigene36450序列进行了克隆, 并应用荧光定量PCR和RNA干扰（RNAi）技术分别对该基因的表达规律和功能进行了研究。结果表明： 克隆的 Unigene36450全长cDNA开放阅读框长585 bp, 编码的蛋白含194个氨基酸, 具有典型的表皮蛋白R&R保守结构域, 命名为NlICP。转录水平的时序表达分析发现, NlICP仅在褐飞虱若虫期表达, 且在3龄若虫体内表达量最高, 提示该基因编码的蛋白属于幼虫表皮蛋白。RNA干扰结果显示, 取食dsNlICP的1龄末2龄初（孵化后第3 天）若虫在干扰6 d和8 d时, NlICP基因的表达量分别较取食dsGFP的对照组下降58.8%和45.6%, 差异极显著(P<0.01); 干扰后部分褐飞虱若虫因蜕皮不完全死亡, 干扰5 d的存活率较对照下降26.7%。本研究结果提示, NlICP与褐飞虱若虫的生长发育及蜕皮相关, 可以作为褐飞虱防治的潜在靶标基因。     

Relative contribution of genetic and environmental factors to determination of wing morphs of the brown planthopper Nilaparvata lugens

Wing dimorphism is a fascinating feature of the ability of insects to adapt to environments. The brown planthopper (BPH) Nilaparvata lugens, a serious pest of rice, can switch between the long- and short-winged morphs. It has been known that environmental factors can affect the wing morph of BPH. However, it is still unclear whether the effect of environment is dependent on BPH genetic backgrounds or not. In the present study, we established the pure-bred lineages of short- and long-winged BPHs via multigenerational selection, and we found that survival and fecundity were similar between these 2 lineages. Wing morphs of the pure-bred lineages were almost fully dependent on genetics, but independent of the environmental factors, nymphal density and rice plant stage, 2 key factors affecting BPH wing morphs. In the unselected BPH population, short- and long-winged morphs were produced depending on those 2 environmental factors, indicating the contribution of environment to wing morph. In the wing-selected lineages, 4 developmental regulated genes of wing, NlInR1, NlInR2, NlAkt, and NlFoxo were expressed stably in the short-winged adults, but almost silenced in the long-winged adults. However, all these genes were expressed normally with a similar level in both the short- and long-winged adults in an unselected population except NlFoxo. The pure-bred lineages of long- and short-winged morphs exhibited different expression patterns of wing development-regulated genes, suggesting the genetic determination of wing morphs. Effects of environmental factors on wing morphs occurred only in the genetic mix population.     

Cultivation,identification and quantification of one species of yeast‐like symbiotes,Candida, in the rice brown planthopper,Nilaparvata lugens

Abstract The brown planthopper (BPH), Nilaparvata lugens Stål, which is one of the most destructive pests of rice, has been confirmed to harbor yeast‐like symbiotes (YLS) in the fat body. Several morphologically different YLS have been previously isolated and cultured in vitro from BPH, but direct evidence is lacking to further clarify whether the cultured YLS were from BPH. In this study, one species of YLS was successfully cultured in vitro and simultaneously verified to exist in the fat body of BPH by sequence analysis and nested polymerase chain reaction (PCR). The cultured YLS isolate in vitro was identified as a member of the genus Candida on the basis of 18S rDNA (ribosomal DNA) and 5.8S‐ITS (internal transcribed spacer) rDNA sequence and a phylogenetic analysis of ITS sequences from yeast. Therefore, this yeast isolate was named as Candida‐like symbiotes. Candida‐like symbiotes was found to exist in fat bodies, ovaries and newly laid eggs of the BPH, but not in the heads, thoraxes and mid‐guts. In addition, the number of Candida‐like symbiotes in 1 × 10⁶ of purified YLS from BPH fat bodies was speculated to be (5.32 ± 0.22) × 10⁴ on the basis of a quantitative PCR analysis.     

褐飞虱热胁迫下内参基因的筛选及热激蛋白基因表达分析（英文）

【目的】褐飞虱Nilaparvata lugens(Stl)是为害水稻的重要害虫之一,温度是影响其暴发、迁飞的主要环境因子之一。本研究旨在探讨研究褐飞虱对高温胁迫适应性的热激蛋白基因表达调控模式。【方法】分别以不同的高温(30℃~40℃)处理褐飞虱雌、雄虫1 h和2 h,利用荧光定量PCR技术检测其体内的β-actin 1,β-actin2,β-actin3,28S rRNA,18S rRNA和α-2-tubulin 6个内参基因的表达量,用geN orm和BestK eeper软件分析确定最稳定表达的内参基因,并检测热胁迫后hsp70和hsp90基因在处理褐飞虱成虫体内的表达模式。【结果】geN orm软件分析结果表明,热胁迫后褐飞虱内参基因稳定性在雌虫体内为:β-actin1=β-actin328S rRNAα-2-tubulin18S rRNAβ-actin2;在雄虫体内为:β-actin1=β-actin3α-2-tubulin28S rRNA18S rRNAβ-actin2。BestK eeper软件分析结果显示,在热胁迫的雌、雄虫体内β-actin1均最稳定,18S rRNA次之,β-actin2最不稳定。两种软件分析结果基本一致。以β-actin1为校正内参基因,荧光定量PCR分析hsp70和hsp90在不同热胁迫条件下的表达模式,结果表明,各高温处理下hsp70表达量与对照26℃下的表达量没有显著性差异;而hsp90基因表达模式表现为被高温诱导上调表达,在雌、雄虫体内表达量达到最高的处理条件分别为40℃和38℃处理2 h。【结论】β-actin1基因可以作为热胁迫下褐飞虱雌雄虫体内基因表达模式分析的校正内参基因使用。褐飞虱hsp90基因能被高温诱导表达,该基因可能在褐飞虱适应热胁迫过程中起着重要的作用。     

Microbiome responses during virulence adaptation by a phloem‐feeding insect to resistant near‐isogenic rice lines

The microbiomes of phloem‐feeding insects include functional bacteria and yeasts essential for herbivore survival and development. Changes in microbiome composition are implicated in virulence adaptation by herbivores to host plant species or host populations (including crop varieties). We examined patterns in adaptation by the green leafhopper, Nephotettix virescens, to near‐isogenic rice lines (NILs) with one or two resistance genes and the recurrent parent T65, without resistance genes. Only the line with two resistance genes was effective in reducing leafhopper fitness. After 20 generations on the resistant line, selected leafhoppers attained similar survival, weight gain, and egg laying to leafhoppers that were continually reared on the susceptible recurrent parent, indicating that they had adapted to the resistant host. By sequencing the 16s rRNA gene, we described the microbiome of leafhoppers from colonies associated with five collection sites, and continually reared or switched between NILs. The microbiomes included 69–119 OTUs of which 44 occurred in ≥90% of samples. Of these, 14 OTUs were assigned to the obligate symbiont Candidatus sulcia clade. After 20 generations of selection, collection site had a greater effect than host plant on microbiome composition. Six bacteria genera, including C. sulcia, were associated with leafhopper virulence. However, there was significant within‐treatment, site‐related variability in the prevalence of these taxa such that the mechanisms underlying their association with virulence remain to be determined. Our results imply that these taxa are associated with leafhopper nutrition. Ours is the first study to describe microbiome diversity and composition in rice leafhoppers. We discuss our results in light of the multiple functions of herbivore microbiomes during virulence adaptation in insect herbivores.     

抗性水稻品种对褐飞虱和白背飞虱种群参数的影响

在半自然状态下 ,用生命表方法初步比较了褐飞虱Nilaparvatalugens和白背飞虱Sogatellafurcif era在 4个抗褐飞虱水稻品种ASD7,IR3 6,JX89和Mudgo上的种群参数。初步的结果表明 ,白背飞虱在 4个抗褐飞虱水稻品种上具有较高的繁殖率 ,较短的发育时间和较大的种群增长。对褐飞虱各种群参数影响最大的是JX89,对白背飞虱影响最大的是Mudgo。与感性品种TN1比较 ,这些抗褐飞虱的水稻品种对 2种稻飞虱均具有不同程度的抗性。这些结果说明 ,抗褐飞虱水稻品种对白背飞虱同样具有一定的抗性 ,但白背飞虱对这种抗性具有较强的适应性 ,如果在一个地区长期推广抗褐飞虱的水稻品种 ,势必会导致白背飞虱的大发生     

利用抑制差减杂交技术分离受水稻抗性调控的褐飞虱基因

为分离受水稻抗性调控的褐飞虱Nilaparvata lugens基因, 以取食感虫水稻台中1号和高抗水稻B5的2叶1芯秧苗24 h的褐飞虱4龄若虫为起始材料, 采用抑制差减杂交技术构建了两个群体间的正反向差减cDNA文库。通过斑点杂交从差减文库中筛选代表受水稻抗性调控的基因的cDNA克隆, 进行测序和功能分析, 挑选具功能的基因进行Northern杂交验证。结果表明, 通过斑点杂交筛选到的98个阳性克隆代表92个互不重复的单基因, 其中25个与动物的已知蛋白基因存在较高的同源性。Northern杂交表明, 这25个基因有11个表达上调, 8个表达下调, 提示它们可能在褐飞虱适应抗性水稻过程中发挥了重要作用。本研究结果为克隆上述新基因的全长cDNA序列及进一步研究其在褐飞虱与水稻互作中的功能奠定了基础。     

Quantitative genetic analysis of biotypes of the brown planthopper Nilaparvata lugens: heritability of virulence to resistant rice varieties

The virulence of Nilaparvata lugens Stål (Homoptera: Delphacidae) to a resistant variety of rice, Oryza sativa L., is suggested to be under polygenic control. To determine whether the virulence of N. lugens is a quantitative character that has continuous distribution or a threshold character that has a few discontinuous phenotypic forms and is determined by some underlying continuous variable, I examined the frequency distribution of honeydew excretion that has been used as a measure of ability of attacking the rice plants, and the relationship between honeydew excretion and the oviposition rate of N. lugens females using a japonica rice line Saikai 190 which has a resistance gene Bph 1. The frequency distribution in honeydew excretion significantly differed from the normal distribution, but two distributions below and above 10 mg honeydew excretion for two days did not significantly deviate from normality, suggesting a bimodal distribution. There were significant differences in the proportion of females ovipositing and the number of eggs deposited between the female groups that excreted 0–10 mg honeydew and more than 20 mg honeydew. Within these female groups, however, the reproductive performances were not different. Thus, virulence of N. lugens can be analyzed as a threshold character that has two distinct phenotypes, virulent and avirulent. I estimated the heritabilities of the virulence of N. lugens by parent-offspring regression using the percentage of virulent females in a full-sib family. The estimates of heritability were 0.41 on Saikai 190 and 0.55 on ASD7, carrying the bph 2 gene. These results show that the N. lugens population has substantial genetic variation in virulence. The regression coefficients on female and male parents were similar, suggesting similar genetic contributions by both parents. When the parental families were examined on Saikai 190 and the progeny on ASD7, the regression coefficient approached zero. There may be a low genetic correlation between virulences to the two varieties.     

Imidacloprid‐induced transference effect on some elements in rice plants and the brown planthopper Nilaparvata lugens (Hemiptera: Delphacidae)

Abstract The widespread use of imidacloprid against insect pests has not only increased the rate of the development of target pest resistance but has also resulted in various negative effects on rice plants and Nilaparvata lugens resurgence. However, the effect of imidacloprid on elements in rice plants and the transference of these element changes between rice and N. lugens are currently poorly understood. The present study investigated changes of Cu, Fe, Mn, Zn, Ca, K, Mg and Na contents in rice plants following imidacloprid foliar sprays in the adult female of N. lugens that develops from nymphs that feed on treated plants and honeydew produced by females. The results indicated that imidacloprid foliar spray significantly increased Fe and K contents in leaf sheaths. Generally, Fe, Mn, K and Na contents in leaf blades were noticeably decreased, but Ca contents in leaf blades for 10 and 30 mg/kg imidacloprid treatments were significantly increased. The contents of most elements except K and Mg in the adult females and honeydew were significantly elevated. Multivariate statistical analysis showed that Fe, Mn and Na in leaf blades and Fe and Mn in leaf sheaths could be proportionally transferred to N. lugens. The relationship between most elements in adult female bodies and in the honeydew showed a positive correlation coefficient. There were significant differences in the contents of some elements in rice plants and N. lugens from different regions.     

Drought stress reduces the feeding preference of Nilaparvata lugens due to the accumulation of abscisic acid and callose deposition in rice

The incidence of drought stress in plants has been increasing due to global warming, and the phytohormone abscisic acid (ABA) induces the formation of physical barriers in plants, such as callose accumulation. The brown planthopper (BPH; Nilaparvata lugens Stål) occurs throughout Asia and feeds on rice, but the effects of drought stress on BPH feeding remain unclear. In this study, we observed changes in callose formation and ABA content in rice during drought stress. ABA content and the relative expression of ABA synthesis genes OsNCED3 and OsNCED5 were higher in drought-stressed rice than the non-stressed control. Similarly, the expression levels of callose synthesis genes and callose deposition were significantly higher in drought-stressed rice as compared to non-stressed plants, and this impacted BPH feeding. Our results indicated that rice resistance to BPH increased during drought stress due to the accumulation of callose and increasing ABA levels. Our findings provide a basis for understanding BPH feeding performance on rice during drought stress and offer novel insights relative to control during periods of water shortage.     

Molecular characterization,spatial‐temporal expression and magnetic response patterns of iron‐sulfur cluster assembly1 (IscA1) in the rice planthopper,Nilaparvata lugens

The mechanisms of magnetoreception have been proposed as the magnetitebased, the chemical radical-pair and biocompass model, in which magnetite particles, the cryptochrome (Cry) or iron-sulfur cluster assembly 1 (IscA1) may be involved. However, little is known about the association among the molecules. Here we investigated the molecular characterization and the mRNA expression of IscA1 in different developmental stages, tissues and magnetic fields in the migratory brown planthopper (BPH), Nilaparvata lugens. NlIscA1 contains an open reading frame of 390 bp, encoding amino acids of 129, with the predicted molecular weight of 14.0 kDa and the isoelectric point of 9.10. Well-conserved Fe-S cluster binding sites were observed in the predicted protein. Phylogenetic analysis demonstrated NlIscA1 to be clustered into the insect's IscA1. NlIscA1 showed up-regulated mRNA expression during the period of migration. The mRNA expression of NlIscA1 could be detected in all the three tissues of head, thorax and abdomen, with the highest expression level in the abdomen. For the macropterous migratory Nilaparvata lugens, mRNA expression of NlIscA1 and N. lugens cryptochromel (Nlcry1) were up-regulated under the magnetic fields of 5 Gauss and 10 Gauss in strength (vs. local geomagnetic field), while N. lugens cryptochrome 2 (Nlcry2) remained stable. For the brachyterous non-migratory Nilaparvata lugens, no significant changes were found in mRNA expression of NlIscA1, Nlcry1 and Nlcry2 among different magnetic fields. These findings preliminarily reveal that the expression of NlIscA1 and Nlcry1 exhibited coordinated responses to the magnetic field. It suggests some potential associations among the putative magneto-sensitive molecules of cryptochrome and iron-sulfur cluster assembly.     

褐飞虱核糖体小亚基蛋白S8基因NlRPS8的克隆及其表达分析

【目的】核糖体蛋白在生物体内具有重要作用,本研究旨在探明核糖体蛋白S8在褐飞虱Nilaparvata lugens生长发育过程中的表达规律和功能。【方法】本文根据褐飞虱基因表达谱提供的差异表达基因信息及转录组提供的基因核心序列,结合褐飞虱基因组比对分析,对褐飞虱核糖体S8基因进行了预测,并通过RT-PCR获得了褐飞虱核糖体小亚基蛋白S8的全长c DNA序列,命名为NlRPS8(Gen Bank登录号:KU341337)。【结果】NlRPS8基因全长627 bp,编码208个氨基酸。进化分析表明,褐飞虱与桑粉介壳虫Maconellicoccus hirsutus亲缘关系最为接近。应用荧光定量PCR分析了基因NlRPS8的表达规律,结果表明,NlRPS8基因在褐飞虱怀卵雌虫中表达量最高,而在雄成虫、初羽化雌成虫与1~5龄若虫表达量相对较低;在褐飞虱体内,NlRPS8基因在卵巢中表达量最高,中肠次之,在其他部位表达量较低。在抗性品种ASD7和RHT上,NlRPS8基因表达量分别为感性品种TN1上的1.99倍和2.14倍。NlRPS8基因在经过饥饿处理1 d的褐飞虱组中表达量为正常组的1.6倍。【结论】研究结果显示NlRPS8基因在褐飞虱生长、繁殖中发挥作用,为进一步研究NlRPS8基因在褐飞虱生长发育和对抗性品种适应中的功能提供了线索。     

Detection and analysis of QTLs for resistance to the brown planthopper, Nilaparvata lugens, in a doubled-haploid rice population

 We used a mapping population of 131 doubled-haploid lines, produced from a cross between an improved indica rice variety (IR64) and a traditional japonica variety (Azucena), to detect quantitative trait loci (QTLs) for resistance to the brown planthopper (BPH), Nilaparvata lugens. We evaluated the parents and mapping population with six tests that measure varying combinations of the three basic mechanisms of insect host plant resistance, i.e., antixenosis, antibiosis, and tolerance. To factor-out the effect of the major resistance gene Bph1 from IR64, the screening was done with two BPH populations from Luzon Island, The Philippines, that are almost completely adapted to this gene. A total of seven QTLs associated with resistance were identified, located on 6 of the 12 rice chromosomes. Individual QTLs accounted for between 5.1 and 16.6% of the phenotypic variance. Two QTLs were predominantly associated with a single resistance mechanism: one with antixenosis and one with tolerance. Most of the QTLs were derived from IR64, which has been shown to have a relatively durable level of moderate resistance under field conditions. The results of this study should be useful in transferring this resistance to additional rice varieties. Received: 10 May 1998 / Accepted: 4 June 1998     

Feeding‐induced changes in defence enzymes and PR proteins and their implications in host resistance to Nilaparvata lugens

Six rice genotypes showing susceptible and resistant reactions to brown planthopper (BPH), Nilaparvata lugens were studied for feeding‐induced changes in defence enzymes and pathogenesis‐related (PR) proteins. The high resistant genotypes PTB 33, ADT 45 and ASD 7 and moderately resistant genotypes CO 43 and KAU 1661 recorded the greater expression of defence enzymes peroxidase, polyphenol oxidase, phenylalanine ammonia lyase, total phenol and β‐1,3 glucanase in response to N. lugens feeding at 1 day after infestation (DAI) compared with susceptible genotype TN1. The greater activity of chitinase was observed in resistant cultivars at 3 DAI and the activity was sustained for more than 1 week compared with susceptible TN1. In conclusion, the current study revealed that these defence enzymes and PR proteins might attribute to the resistance mechanisms in rice plants against BPH infestation.     

Characterization of a Nilaparvata lugens (Stål) brummer gene and analysis of its role in lipid metabolism

The brummer (bmm) genes encode the lipid storage droplet‐associated triacylglycerols (TAG) lipases, which belong to the Brummer/Nutrin subfamily. These enzymes hydrolyze the ester bonds in TAG in lipid metabolism and act in insect energy homeostasis. Exposure to some agricultural chemicals leads to increased fecundity, which necessarily involves lipid metabolism, in some planthopper species. However, the biological roles of bmm in planthopper lipid storage and mobilization have not been investigated. Here, the open reading frame (ORF) of bmm (Nlbmm) was cloned and sequenced from the brown planthopper (BPH; Nilaparvata lugens). The ORF is 1014 bp encoding 338 amino acid residues. Nlbmm contained patatin domains and shared considerable evolutionary conservation with other insect bmms. Nlbmm is highly expressed in the fat body, consistent with its roles in lipid metabolism. Injection with Nlbmm double‐stranded RNA (dsNlbmm) led to reduced Nlbmm mRNA accumulation, but did not influence expression of several genes related to lipid synthesis including acyl‐CoA‐binding protein (ACBP), acetyl‐CoA carboxylase (ACC), and a lipophorin receptor (LpR). Nlbmm knockdown led to increased TAG contents in whole bodies, accumulation of total fat body lipid, and decreased hemolymph lipid content. Nlbmm knockdown did not influence the synthesis and distribution of glycerol. We infer that Nlbmm acts in TAG breakdown and fat metabolism in N. lugens.     

褐飞虱危害粳稻稻穗及原因分析

1998年 ,东台市出现了历史上罕见的水稻褐飞虱危害粳稻稻穗的现象 ,对水稻的产量影响较大。本文就其发生的原因进行了分析。