The multicopper oxidase gene family in the brown planthopper,Nilaparvata lugens

The multicopper oxidase (MCO) family of enzymes includes laccases, ascorbate oxidases, bilirubin oxidases and a subgroup of metal oxidases. On the basis of a bioinformatics investigation, we identified 7 genes encoding putative multicopper oxidase proteins in the genome of the brown planthopper (BPH), Nilaparvata lugens (Hemiptera: Delphacidae). MCO1 and MCO2 are conserved, while others diverse in insects. Analysis of developmental and tissue-specific expression patterns revealed the following: NlMCO2 was mainly expressed in the integument, and its expression peaked periodically during molting; NlMCO3 was an ovary-specific MCO gene with a high expression level only at the adult stage; NlMCO4 was a salivary gland-specific MCO gene that was expressed at all developmental stages; NlMCO5 only had short-term expression in the middle of the fourth instar stage and was expressed mainly in the gut; NlMCO6 had a developmental expression pattern similar to that of NlMCO2 and was expressed in most N. lugens tissues; and NlMCO1 was expressed in most N. lugens tissues except for the testis, whereas NlMCO7 was mainly expressed in the gut and the Malpighian tube. BPHs injected with double-stranded RNA (dsRNA) targeting NlMCO2 failed to pigment and sclerotize, were colorless and soft-bodied and subsequently died in a short time. Lethal phenotypes were also observed in insects challenged by dsRNA targeting NlMCO6. However, no observable morphological or internal structural abnormality was obtained in the insects treated with dsRNA for NlMCO1, NlMCO3, NlMCO4, NlMCO5 or NlMCO7.     

Carboxylesterase genes in nitenpyram-resistant brown planthoppers,Nilaparvata lugens

Carboxylesterases (CarEs) represent one of the major detoxification enzyme families involved in insecticide resistance. However, the function of specific CarE genes in insecticide resistance is still unclear in the insect Nilaparvata lugens (Stål), a notorious rice crop pest in Asia. In this study, a total of 29 putative CarE genes in N. lugens were identified, and they were divided into seven clades; further, the β-esterase clade was significantly expanded. Tissue-specific expression analysis found that 17 CarE genes were abundantly distributed in the midgut and fat body, while 12 CarE genes were highly expressed in the head. The expression of most CarE genes was significantly induced in response to the challenge of nitenpyram, triflumezopyrim, chlorpyrifos, isoprocarb and etofenprox. Among these, the expression levels of NlCarE2, NlCarE4, NlCarE9, NlCarE17 and NlCarE24 were increased by each insecticide. Real-time quantitative polymerase chain reaction and RNA interference assays revealed the NlCarE1 gene to be a candidate gene mainly involved in nitenpyram resistance, while simultaneously silencing NlCarE1 and NlCarE19 produced a stronger effect than silencing either one individually, suggesting a cooperative relationship in resistance formation. These findings lay the foundation for further clarification of insecticide resistance mediated by CarE in N. lugens.     

Determination and distribution of a female-specific protein in the brown planthopper, Nilaparvata lugens Stal (Homoptera: Delphacidae)

Electrophoretic analyses of hemolymph and body or ovary homogenates from reproducing females, males, and 5th instar nymphs of the brown planthopper, Nilaparvata lugens Stal, revealed a protein band of 175 kDa in females. An immunoblot test using antibody against this protein showed a positive reaction with a 175 kDa protein from female body or ovary homogenates. It is likely that this protein in hemolymph is vitellogenin (Vg). Distribution of Vg was determined by immunofluorescence and immunogold labeling techniques. The results showed that the positive immunofluorescence reactions were present in yolk particles, the intercellular space of follicle cells, hemolymph, and the epithelial plug of ovarioles. In addition, the yeast-like symbiotes (YLS) in mycetocytes of adults and various nymphal instars as well as those free in hemolymph or entering oocytes also exhibited a positive reaction. Electron micrographs showed that immunogold particles were found most in yolk mass and YLS over other tissues. Especially the YLS in various developmental stages all contained immunogold particles, implying that the symbiote is somewhat related with production of the female-specific protein.     

褐飞虱体内保幼激素滴度变化及其与翅型分化的关系

用高压液相色谱及放射化学法,分别测定了褐飞虱Nilaparvata lugens 1～5龄若虫体内的保幼激素滴度与保幼激素酯酶活性变化,并用保幼激素类似物(ZR-515)进行体表点滴加以验证。结果表明,褐飞虱雌、雄4龄若虫期及雄虫的5龄若虫初期,短、长翅型间体内保幼激素滴度差异明显,可以认为该阶段是其翅型分化的关键时期。     

Role of different habitats for the functional response of Crytorrhinus lividipennis (Hemiptera: Miridae) on Nilaparvata lugens (Hemiptera: Delphacidae)

The functional response of a predator, Cyrtorrhinus lividipennis, on the brown planthopper, Nilaparvata lugens, was investigated in two different experimental habitats: a piece of tiller in a petri dish (5.5?cm in diameter) and a rice plant in a net cage (5.5?cm diameter?×?43?cm height) for 24?h at room temperature. In the petri dish experiment, 2nd–5th instar nymphs, adult male, and female C. lividipennis were introduced in separate experiments to eggs of N. lugens at densities of five, 10, 20, 30, and 40 eggs per piece of rice. In the rice plant experiment, each C. lividipennis was introduced to a cage with a rice plant containing N. lugens eggs. After 24?h, the number of dead eggs and remaining eggs were counted and data fitted to three functional response models. Among the three types of functional responses, Type II best described the predator response to host densities in N. lugens in both experimental habitats, according to the logistic regression analysis value. The results showed that C. lividipennis was a more effective predator in the rice plant experiment compared to the disc experiment. Additionally, the searching efficiency and handling time parameters were different in the two different experimental habitats. This may cause errors when applying the functional response to biological control and predator–prey models. Different habitats and other environmental conditions from the experiment and natural rice field have to be considered.     

Sublethal effects of abamectin on the development,fecundity, and wing morphs of the brown planthopper Nilaparvata lugens

The brown planthopper Nilaparvata lugens negatively affects rice yield by sucking nutrients from the rice stem and spreading viruses. In this study, the effects of sublethal concentrations of abamectin on development, fecundity, and wing morphs of N. lugens were investigated. Treatment with sublethal concentrations of abamectin showed no significant effects on the developmental period of F₀ nymphs. Although LC₁₀ and LC₂₅ treatments resulted in 10% and 25% mortality, the LC₂₅ treatment significantly prolonged the lifespan of macropterous and brachypterous females. Abamectin-treated brachypterous females showed significantly lower fecundity than control females. Furthermore, abamectin treatment showed no significant effects on the developmental period of F₁ nymphs. However, LC₂₅ treatment significantly inhibited the fecundity of brachypterous F₁ females and significantly reduced the proportion of macropterous F₁ females and brachypterous F₁ males. LC₂₅ treatment showed no significant effects on the fecundity of macropterous F₁ females. Considering the proportion of macropterous and brachypterous F₁ females, the relative fitness of the macropterous F₁ nymphs in the control, LC₁₀, and LC₂₅ treatment groups was 1, 1.02, and 0.84, respectively, and that of brachypterous F₁ nymphs was 1, 0.79, and 0.93, respectively. Sublethal concentrations of abamectin inhibited N. lugens emergence. The present findings indicate the potential of abamectin for N. lugens field control.     

Tagging the brown planthopper,Nilaparvata lugens,with the stable isotope nitrogen-15; method for labelling and detection

The brown planthopper (BPH), Nilaparvata lugens (***Stål), is a serious pest of rice in tropical Asia (IRRI, 1979).     

Wing polymorphism in Japanese and foreign strains of the brown planthopper, Nilaparvata lugens

Great variations in nymphal density and wing-form relationships occur in field populations of the brown planthopper, Nilaparvata lugens (Stål) (Homoptera: Delphacidae). When tested under uniform laboratory conditions, half of the female populations collected from 20 locations in Japan exhibited higher ratios of macropters with increasing nymphal density, but one quarter were macropterous over broad ranges of density, both types being classified as group III. Three predominantly brachypterous populations (group I) were found, even under crowded conditions and one intermediate (group II).The populations from South Asian countries, i.e. Philippines (one), Indonesia (two) and Malaysia (one) belonged to group I, but the three populations from the coastal areas of China belonged to group II. Those from Taiwan differed in responses to density; one was of group II type, and two of group III type.From these comparisons, immigration routes of N. lugens to Japan were estimated, and survival strategy of this migratory species is discussed.

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Zusammenfassung In Feldpopulationen von Nilaparvata lugens (Stål) (Homoptera: Delphacidae) gibt es grosse Variationen in der Larvendichte und in den Flügelform-Beziehungen. Unter einheitlichen Laboratoriumsbedingungen wurden diese Verhältnisse geprüft. Von 20 japanischen Herkünften zeigte die Hälfte der Weibchenpopulationen mit zunehmender Larvendichte einen höheren Macropterenanteil; ein Viertel was über einen grossen Dichtebereich macropter; beide Typen werden als Gruppe III bezeichnet. Drei Populationen wurden gefunden, die auch bei hoher Dichte vorwiegend brachypter waren (Gruppe I). Einer Zwischengruppe (II) gehörte eine einzige Population an.Die Populationen aus südasiatischen Ländern (1 aus den Philippinen, 2 aus Indonesien un 1 aus Malaysia) gehörten zu Gruppe I, die 3 Populationen aus den Küstenregionen von China jedoch zu Gruppe II. Die Populationen aus Taiwan unterschieden sich in der Reaktion auf die Dichte: 1 gehörte zu Gruppe II and 2 zu Gruppe III.Von diesen Daten werden Einwanderungswege von N. lugens nach Japan abgeleitet und die Überlebensstrategie dieser Wanderart diskutiert.

     

Molecular characterization,tissue and developmental expression profiles of cryptochrome genes in wing dimorphic brown planthoppers,Nilaparvata lugens

Cryptochromes (CRYs) are blue and UV light photoreceptors, known to play key roles in circadian rhythms and in the light‐dependent magnetosensitivity of insects. Two novel cryptochrome genes were cloned from the brown planthopper, and were given the designations of Nlcry1 and Nlcry2, with the accession numbers KM108578 and KM108579 in GenBank. The complementary DNA sequences of Nlcry1 and Nlcry2 are 1935 bp and 2463 bp in length, and they contain an open reading frame of 1629 bp and 1872 bp, encoding amino acids of 542 and 623, with a predicted molecular weight of 62.53 kDa and 70.60 kDa, respectively. Well‐conserved motifs such as DNA‐photolyase and FAD‐binding‐7 domains were observed in Nlcry1 and Nlcry2. Phylogenetic analysis demonstrated the proteins of Nlcry1 and Nlcry2 to be clustered into the insect's cryptochrome 1 and cryptochrome 2, respectively. Quantitative polymerase chain reaction showed that the daily oscillations of messenger RNA (mRNA) expression in the head of the brown planthopper were mild for Nlcry1, and modest for Nlcry2. Throughout all developmental stages, Nlcry1 and Nlcry2 exhibited extreme fluctuations and distinctive expression profiles. Cryptochrome mRNA expression peaked immediately after adult emergence and then decreased subsequently. The tissue expression profiles of newly emerged brown planthopper adults showed higher expression levels of CRYs in the head than in the thorax or abdomen, as well as significantly higher levels of CRYs in the heads of the macropterous strain than in the heads of the brachypterous strain. Taken together, the results of our study suggest that the two cryptochrome genes characterized in the brown planthopper might be associated with developmental physiology and migration.     

褐飞虱2009年秋季回迁的雷达监测及轨迹分析

褐飞虱Nilaparvata lugens (Stål)是水稻生产上重要的迁飞性害虫,研究其迁飞、扩散规律,为早期预警和有效防治提供科学依据。2009年4月27日至10月11日, 在中国农业科学院植物保护研究所重大病虫害监测预警兴安雷达站内利用毫米波扫描昆虫雷达对褐飞虱的迁飞过程进行长期观测,高空探照灯诱虫器及佳多自动虫情测报灯诱虫器分别用来诱捕高空及地面的褐飞虱,对高空探照灯诱到的褐飞虱雌成虫随机挑选30头进行卵巢解剖, 并结合大区环流和利用Hysplit_4模型进行轨迹分析,研究了褐飞虱的秋季回迁过程和虫源。结果表明：褐飞虱秋季回迁高峰期出现在9月28日至10月7日,高峰日为10月1日, 高峰日内雷达回波主要在600~1 100 m范围内聚集成层,高空探照灯诱虫器内褐飞虱的数量达到了13 620头;卵巢发育级别以1~2级为主。轨迹分析显示：本次回迁的褐飞虱主要来自湖南衡阳和永州等地,随东北气流向广西柳州、南宁和崇左等方向迁飞。轨迹推断与褐飞虱实发虫情基本吻合,通过毫米波扫描昆虫雷达确定了褐飞虱秋季回迁的高度,为毫米波扫描昆虫雷达早期投入到预测预报的实践中奠定了基础,对我国褐飞虱早期预警体系的建立将提供必要的技术支持。     

水稻品种中抗褐飞虱抗原次生物质的分析

借助高效液相色谱(HPLC)技术,研究了130份对褐飞虱生物型Ⅱ具有不同抗性水平的水稻样品(26个品种)中13个次生物质含量(峰面积)的差异;运用主成分分析和多元回归分析,建立了水稻品种抗性级别的预测模型：Y=3．4593-0．02491X1+0．08475X2-0．04227X8+0．1174X12结果表明,水稻的抗性水平与峰面积值之间极显著相关(r^2=0．84,P<0．01),峰1、峰2、峰8、峰12对应的次生化合物是影响水稻对褐飞虱生物型Ⅱ抗性水平的主要抗原次生化合物;水稻品种中起抗虫作用的抗原次生物质不止一种,而是几种的组合,而且它们对水稻抗虫性的贡献权重是不完全相同的．     

安庆褐飞虱近三个大发生年虫源和气候条件的比较分析

比较并分析安庆市1997,2005年和2006年褐飞虱Nilaparvata lugehs(Stal)大发生的虫源、气候条件。1997年,迁入期偏早,初迁虫量大,到7月26日止,单灯累计诱量为1228~8698头;7、8月份气温比历史均值低0.2~1.3℃,导致单季稻上基数适温协同暴发型;再迁补充虫源峰次较多,但9月份气温比历史均值低1.0℃,抑制了双季晚稻褐飞虱发生。2005年,迁入期较早,但初迁虫量低,到7月26日止,单灯累计诱量为200~3334头;7月中旬至8月份气温比历史均值低0.4~0.8℃,9月至10月中旬气温比历史均值高1.8~2.2℃,有利褐飞虱发生的气候条件长达3个月;同时,夏、秋季台风暴雨频繁,再迁补充虫源丰富,8月16日~9月25日每侯灯下≥1000头的回迁峰次多达5个,分别比1997年和2006年多1个和2个,导致多代连续重发。2006年,迁入期早,6月底以前的早迁虫量分别是1997年和2005年同期的6.4倍和2.1倍,初迁虫量大,到7月26日止,单灯累计诱量为1595~7181头;虽然7、8月份气温比历史均值高1.0~2.0℃,但单季稻田间小气候适宜,构成单季稻基数暴发型;再迁补充虫源峰次较少,但8月底~9月初短期内大量集中迁入,9月下旬至10月份气温异常偏高,高于历史均值1.5~3.0℃,引起晚稻持续重发。     

褐飞虱的降落机制

应用MM5中尺度数值模拟模式和GRADS气象图形软件,对1999年6月22日～7月2日一次褐飞虱迁飞降落过程及其大气背景场进行了个例研究,并侧重对灵川、东至、徽州3个站点的降虫机制做了分析。结果表明：（1）此次迁飞过程有两个明显的降虫区：天柱．灵川．贺县一线范围内（降虫区Ⅰ）和三都-天柱-黔阳-修水-东至-徽州-奉贤-线（降虫区Ⅱ）;（2）低空急流为褐飞虱北迁提供了运载气流,降虫区位于降水区边缘;（3）地形降水胁迫害虫降落是降虫区Ⅰ褐飞虱降落的主要原因,梅雨锋降水导致了褐飞虱集中降落在降虫区Ⅱ;（4）虫源的空间分布差异和不同的天气条件导致了东至、徽州地区不同的降虫分布。     

江苏沿江和江淮区褐飞虱前期迁入量与太平洋海温场的遥相关及其可能机制

为筛选出有效的长期预测因子,对江苏通州和江苏淮安褐飞虱前期迁入量与太平洋海温场遥相关时空分布分别进行了相关分析及其稳定性检验。结果表明： 与褐飞虱前期迁入量连续稳定显著相关的海温区,在空间上主要分布在中太平洋和南太平洋（72.4%）,在时间上主要分布在前两年和前一年（82.7%）。分别分析褐飞虱前期迁入量与当年4-8月上旬各旬降水量、平均温度、当年1-8月500 hPa西太平洋副高月平均指数之间的两两相关关系,并比较这三者与前期太平洋海温场遥相关时空分布的异同。根据对两地的个例分析表明：前一冬春季赤道中东太平洋海温的变化引起当年6月副高面积指数的变化,影响江苏通州当年6月下旬降水,从而影响江苏通州褐飞虱的前期迁入量;前两年春夏季赤道中东太平洋海温的变化引起当年5月副高北界位置的变化,影响江苏淮安当年7月上旬降水,从而影响江苏淮安褐飞虱的前期迁入量。在此基础上,对褐飞虱前期迁入量与太平洋海温场遥相关的可能机制提出“海温→大气环流（副高）→气候→褐飞虱前期迁入"的一般假想模式。     

几种植物次生物质对褐稻虱种群的控制作用模拟

为探讨褐稻虱Nilaparvata lugens (Stål)种群生态控制的作用机理,应用状态空间方程和作用因子添加分析法,研究植物次生物质不同组合对褐稻虱种群的控制作用;本研究以薇甘菊Mikania micrantha乙醇提取物、 飞机草Eupatorium odoratum乙醇提取物与现代苦楝Melia azedarach油的不同组合,作用于褐稻虱种群;根据不同虫期的调查数据,拟合出控制矩阵中各分块矩阵的元素值,并对褐稻虱种群的控制作用进行模拟。结果表明：单独施用薇甘菊乙醇提取物（1 g DW/100 mL）、飞机草乙醇提取物（1 g DW/100 mL）、 现代苦楝油（200倍）各1次, 能显著降低褐稻虱种群数量, 然而种群趋势指数I（population trend index）仍在1.00以上,即下代褐稻虱种群仍呈增长趋势,联合添加其中2种或3种能持续控制褐稻虱下代种群的增长。同时,植物次生物质对褐稻虱种群的控制作用主要表现在对成虫产卵的忌避作用,尤其是在本田种群建立的初期,由于其显著的忌避作用, 降低田间卵量,使其种群数量明显降低,可有效地控制其为害。     

Inheritance of body color in the brown planthopper, Nilaparvata lugens

The segregation frequencies of color phenotypes of F₁, F₂, and backcross progenies revealed that the body coloration of the brown planthopper, Nilaparavata lugens(Stål), exhibited multiple allelism. Monogene for color morphism exists in three allelic forms >-b ⁺ (brown or wild type), b ^o (orange) and b ^b (black). The dominance relationship was b ^b>b ⁺>b ^o. The relationship between phenotype and genotype in N. lugens was not fixed. The six possible genotypes produced eight phenotypes.

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Résumé Les fréquences de ségrégation des différentes colorations de F₁, F₂ et des croisements en retour ont montré que la coloration du corps de Nilaparvata lugens est due à un multi-allèlisme. Le monogène pour la couleur existe sous trois formes allèliques: b⁺ (brun ou sauvage), b^o (orange) et b^b (noir). Les relations de dominance étaient: b^b>b⁺>b^o. On n'a pas établi les relatios entre phénotypes et génotypes chez N. lugens. Les 6 génotypes possibles produisent 8 phénotypes.

     

Sensitive periods for wing development and precocious metamorphosis after precocene treatment of the brown planthopper,Nilaparvata lugens

The critical periods for juvenile hormone suppression of wing development and metamorphosis were examined in a pure brachypterous line of Nilaparvata lugens following topical application of Precocene II (PII) to various stages of the third and fourth nymphal stadia. When PII, in doses ranging from 10 pg to 100 ng, was applied to 12-h-old third or 6-h-old fourth stadium nymphs, long-wing formation (macroptery) was induced. Macropter induction ranged from 5 to 50% in females and from 30 to 50% in males, the effect being more prominent in males. The sensitive period for macropter induction lasted from the early second stadium through to day one of the fourth (penultimate) stadium. Beyond that period nymphs required sensitivity to PII and the numbers of macropters increased towards the final nymphal molt, again males were more sensitive. On the other hand, periods sensitive to PII for precocious metamorphosis induction appeared from early second stadium to 18 h after molting to the third nymphal stadium. Overlapping application of JH-III with PII at early third stadium could totally inhibit the occurrence of precocious metamorphosis and significantly rescue the macropter induction. From the data described, a scheme is presented for the control of wing development and metamorphosis by juvenile hormone, assuming two types of threshold value determining wing form and metamorphosis.     

Meiosis in males of the brown planthopper, Nilaparvata lugens

Meiosis in spermatocytes was studied among the three biotypes of the brown planthopper, Nilaparvata lugens (Stål). The chromosome number, morphology, and behavior of the biotypes were similar. The autosomes divided normally, reductional for the first division and equational for the second. The X chromosome had an unstable segregation behavior; it may segregate equationally or reductionally during the first division depending on its chromatid's orientation. Metaphase I plates contained 14 autosomal bivalents and an X chromosome (14_II + X). The co-oriented sister chromatids of the X chromosome moved together to either one of the poles during anaphase I, while auto-oriented sister chromatids segregated to opposite poles. Because of the anomalous segregation behaviour of the X chromosome, metaphase II plates may both contain 14_I + X chromatid, or one with only 14_I and the other with 14_I + X chromosome. Male N. lugens has a diploid chromosome number of 29.

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Zusammenfassung Die Meiose in Spermatozyten wurde in drei Biotypen von Nilaparvata lugens (Stål) studiert. Die Anzahl der Chromosomen, die Morphologie und das Verhalten der Biotypen waren ähnlich. Die Autosomen teilten in einer normalen Weise, reduzierend für die erste und äquatorial für die zweite Teilung. Das X-Chromosom hatte ein unstabiles Teilungsverhalten; es kann sich äquatorial oder aber auch reduktional trennen, je nachdem wie sich sein Chromatid orientiert hat. Die Ebenen der Metaphase I enthalten 14 autosome Bivalente und ein X-Chromosom (14_II + X). Die co-orientierten Schwester-chromatiden des X-Chromosoms bewegen sich während der Anaphase I zusammen zu einem der beiden Pole, während auto-orientierte Schwester-chromatiden sich nach entgegengesetzten Polen trennen. Wegen des ungewöhnlichen Teilungsverhaltens des X-Chromosoms, können beide Metaphase II Ebenen 14_I und X Chromatid enthalten, oder aber eine Ebene enthält 14_I und die andere 14_I + X.