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.

     

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.

     

稻褐飞虱的DNA遗传变异性分析

稻褐飞虱Ｎｉｌａｐａｒｖａｔａｌｕｇｅｎｓ生物型差异的研究,过去主要局限于形态学、生物学和细胞学比较及同功酶的多态性分析,对种群遗传变异规律的研究仅仅是进行经典的遗传分析。本文应用ＲＡＰＤ技术对褐飞虱种群的遗传变异进行了初步研究,以探讨褐飞虱是否存在明显的生物型分化。1　材料与方法11　虫源试虫采自中国水稻研究所养虫室。分别用品种ＴＮ1(无抗虫基因)、Ｍｕｄｇｏ(携带抗虫基因Ｂｐｈ1)和ＡＳＤ7(携带抗虫基因ｂｐｈ2)强迫饲养30代以上。以寄主名称的第一个字母区分三个不同来源的种群,即Ｔ种群、Ｍ种群和Ａ种群。采集…     

Pesticide-induced susceptibility of rice to brown planthopper Nilaparvata lugens

The effects of rice plants treated with various pesticides (jingganmycin, bisultap and methamidophos) on feeding, survival rates and population growth of Nilaparvata lugens Stål (Homoptera: Delphacidae), susceptibility of the treated rice plants and amounts of free amino acids and sucrose were studied. Experiments indicated that the effects of the tested pesticides were dependent on nymphal age, pesticide and their dose and time after application. Jingganmycin at 75 g a.i. ha^–1 significantly increased the N. lugens population. Both jingganmycin and bisultap increased the survival rate of N. lugens nymphs. The feeding rate of the insects was also affected by the pesticide application, but the effect varied between nymphal age and time after application and lasted no longer than 15 d. Results clearly indicated that pesticide application increased the susceptibility of rice plants to N. lugens. Although the free amino acids in rice plants did not change with the pesticide treatments, the concentration of sucrose significantly decreased 5 d after application and the C/N ratio significantly decreased in jingganmycin treated plants 5 d and 10 d after application.     

褐飞虱抗药性研究现状

褐飞虱Nilaparvata lugens(Stal)对杀虫剂产生抗药性是其近年来暴发频繁的重要原因。文章综述国内外关于褐飞虱抗药性的研究成果,包括褐飞虱抗性测定方法、抗药性的发展、交互抗性、抗性遗传、抗性机理及抗性治理等。田间褐飞虱种群对新烟碱类药剂产生不同程度的抗药性,其中对吡虫啉产生高水平到极高水平抗性,对氯噻啉和噻虫嗪分别产生中等水平和低水平的抗药性,对呋虫胺和烯啶虫胺仍然处于敏感性阶段。此外,褐飞虱种群对噻嗪酮(昆虫生长调节剂)产生低水平到中等水平抗性。长期大面积使用化学药剂是褐飞虱产生抗药性的重要原因。因此,必须加强褐飞虱的抗性治理,以延缓其抗药性进一步发展。     

褐飞虱对吡虫啉抗性监测方法的研究

从结果的稳定性、准确性和操作方便等角度出发 ,建立了适合于监测褐飞虱 (NilaparvatalugensSt l)对吡虫啉抗性的稻苗浸根法。与其他方法相比 ,该方法除具有简单易行的特点外 ,还表现出很好的监测准确性。通过建立不同虫态和不同若虫龄期敏感基线以及对桂林、安庆、东台 3个地区的抗性监测 ,发现 3地褐飞虱对吡虫啉都处于敏感性下降阶段 ,安庆和东台地区的敏感性弱低于桂林     

Two endosymbiotic bacteria, Wolbachia and Arsenophonus, in the brown planthopper Nilaparvata lugens

The brown planthopper Nilaparvata lugens harbors intracellular fungal yeast-like symbionts and endosymbiotic bacteria, with the latter mainly comprising Wolbachia and Arsenophonus. In this study, Wolbachia or Arsenophonus were detected in all 15 brown planthopper populations collected from China and Southeastern Asian countries. Furthermore, Polymerase Chain Reaction (PCR) analysis of the individuals in a population that was infected by both Wolbachia and Arsenophonus showed that each individual was infected by only one of the two symbiotic bacteria. Real-time quantitative PCR showed that both endosymbionts are mainly localized in the mycetocytes of the fat body. Reciprocal crosses between the Wolbachia ⁺ and Arsenophonus ⁺ brown planthopper populations showed that both bacteria were maternally transmitted. Our results showed that the brown planthopper populations are extensively infected by Wolbachia or Arsenophonus, and the two bacteria may be exclusive in each host individual. This finding might be helpful for further studies on the biological functions of the endosymbiotic bacteria and will deepen our understanding of the complicated symbiosis system in this host.     

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.

     

虫害诱导的水稻挥发物对褐飞虱的驱避作用

水稻叶片在遭受害虫的危害时,释放一些特异性的挥发性物质。这些挥发性信息物质在调节植物、植食性昆虫及其天敌的相互关系中有重要作用。利用“Y”型嗅觉仪研究了褐飞虱对虫害诱导的11种水稻挥发物（浓度为2 Μl 化合物溶解在100 Μl丙酮溶液中）的行为反应。结果表明,(E)-2-己烯醛、(E)-2-己烯-1-醇、-2-庚醇和水杨酸甲酯等4种化合物对褐飞虱成虫有显著的驱避作用,而(Z)-3-己烯-1-醇、-2-庚酮、柠檬烯、罗勒烯、芳樟醇、-β-子丁香烯和橙花叔醇等7种物质对褐飞虱成虫的选择行为无显著影响。浓度梯度的实验表明,浓度(不同体积的待测化合物用100 Μl丙酮稀释)较低的(E)-2-己烯醛（0.5 Μl、1 Μl）和芳樟醇（05 Μl、1 Μl、5 Μl）对褐飞虱成虫的选择行为无显著影响,而较高浓度的(E)-2-己烯醛（5 Μl、10 Μl）和芳樟醇（10 Μl）对褐飞虱成虫均有明显的驱避作用。     

Specificity of acoustic signals and mate choice in the brown planthopper Nilaparvata lugens

Mate choice experiments were made between populations of N. lugens from the Philippines, Solomon Is. and northern Australia. Significant barriers to mating were found between the Australian insects and the other two populations. The acoustic signals of successful males in hybridisation experiments were recorded and their pulse repetition frequencies (PRFs) were compared with the mean PRF for a random sample from their own population. In crosses between insects from Australia and the Philippines or Solomon Is. succesful males were characterised by PRFs significantly different from their own populations and closer to those of the female populations in each cross than to their own. It is concluded that PRF of male calls is an important species recognition signal in N. lugens.

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Résumé La communication sexuelle de N. lugens s'effectue par signaux acoustiques transmis par le substrat. Quelques populations géographiquement définissables diffèrent par la fréquence des répétitions des impulsions (PRF) produits par les appels des mâles. Des populations des Philippines, des Iles Salomon et de l'Australie du Nord ont été étudiées.Des expériences de sélection sexuelle ont montré que des obstacles au transfert de spermatozoïdes apparaissaient dans les croisements qui impliquent un parent originaire de la population australienne. Des expériences dhybridation ont été répétées entre individus males et females de chacune des 3 populations étudiées. Le taux de succès étrait faible quand l'un des parents était originaire d'Australie. Le PRF des males de chaque croisement réussi a été déterminé et comparé au PRF moyen d'un échantillon constitué au hasard de males provenant de la même population. Pour les croisements impliquant un parent australien, le PRF des males victorieux différait de la moyenne et se rapprochait de celui des males de la population dont dérivait la female.On en a conclu que le PRF des appels males est important dans la reconnaissance spécifique de N. lugens, mais que chaque population montre un polymorphisme important pour ce caractère.

     

Flight duration of the brown planthopper, Nilaparvata lugens (Homoptera: Delphacidae)

ABSTRACT.

• 1 The brown planthopper, Nilaparvata lugens (Stål), is a major pest of rice in Asia. It is known to make wind-assisted migratory flights each year to colonize the summer rice growing areas of China, Japan and Korea.
• 2 Modelling windborne displacements between rice growing areas in Asia requires migratory behaviour and flight duration to be established for this insect.
• 3 Field and laboratory observations suggest that N. lugens take-off at dusk and that some continue flying for up to 24–26 h if the temperature is ≥ 17°C.
• 4 Trajectories for 10 m above ground level and 1.5 km above mean sea level are used to identify possible sources and, hence, to estimate the flight times of N.lugens caught in nets on ships on the East China Sea in 1973 and 1981.
• 5 Estimated flight times between the sources and the ships ranged from about 9 to 30 h.
• 6 Results suggest that long-distance migration can occur in surface winds, when they are strong, but that long-distance migration is more likely at 1.5 km.
• 7 When simulating windborne displacements of N.lugens, it can be assumed that in areas and at heights where the temperature is ≥ 17°C, some migrants will fly downwind for up to 30 h after a dusk take-off. Others will fly for shorter periods, giving the population as a whole the opportunity to colonize all the rice crops flown over.

     

Genetic mapping of the rice resistance-breaking gene of the brown planthopper Nilaparvata lugens

Host plant resistance has been widely used for controlling the major rice pest brown planthopper (BPH, Nilaparvata lugens). However, adaptation of the wild BPH population to resistance limits the effective use of resistant rice varieties. Quantitative trait locus (QTL) analysis was conducted to identify resistance-breaking genes against the anti-feeding mechanism mediated by the rice resistance gene Bph1. QTL analysis in iso-female BPH lines with single-nucleotide polymorphism (SNP) markers detected a single region on the 10th linkage group responsible for the virulence. The QTL explained from 57 to 84% of the total phenotypic variation. Bulked segregant analysis with next-generation sequencing in F₂ progenies identified five SNPs genetically linked to the virulence. These analyses showed that virulence to Bph1 was controlled by a single recessive gene. In contrast to previous studies, the gene-for-gene relationship between the major resistance gene Bph1 and virulence gene of BPH was confirmed. Identified markers are available for map-based cloning of the major gene controlling BPH virulence to rice resistance.     

Determining the geographic origin of the brown planthopper,Nilaparvata lugens,using trace element content

Abstract A chemometric study using pattern recognition technology was carried out to characterize the geographic origins of the brown planthopper, Nilaparvata lugens. The concentrations of 23 trace elements (Mn, Mo, Cd, Ce, V, Th, Cs, Be, Tl, Fe, Nd, Pr, Se, Tm, Lu, Eu, Ho, Br, Dy, Gd, U, Sm and Er) in 53 samples from seven regions in southern China were determined using inductively coupled plasma mass spectrometry. The data obtained were successively evaluated using a multivariate statistical approach, namely, linear discriminant analysis, which allowed classification and discrimination of the N. lugens samples from Fuqing, Shaoguan, Hepu, Yongfu, Hengnan, Wan‐an and Yongkang with high accuracy and a clear separation among the seven regions. The results show that pattern identification on the basis of trace elements in the bodies of N. lugens is feasible for determining the geographic origins of individuals.     

An orange-eye mutant of the brown planthopper,Nilaparvata lugens (Hemiptera: Delphacidae)

An orange-eye mutant of the brown planthopper (BPH), Nilaparvata lugens (Stål), was found in a green house and has since been maintained together with a normal-eye phenotype of BPH in an insectary. The orange color was expressed in all developmental stages of BPH: the eye spots of eggs and the eyes of nymphs and adults of both sexes and wing forms. Cross-mating results suggested that the inheritance of the orange-eye phenotype is controlled by a single autosomal recessive allele. The gene symbol related to this mutant was designated as “org”. Developmental duration and mortality of nymphal stages were not significantly different between the normal phenotype (homozygous and heterozygous) and the mutant. In addition, reproduction was not significantly different among mating combinations of the three BPH genotypes (+/+, +/org, org/org). The effect of eye color on mating of BPH was insignificant in a mate choice test which consisted of one orange-eye female, one orange-eye male, and one homozygous normal-eye male. Offspring produced by the orange-eye female BPH hatched and developed into adults normally, indicating that the eye color mutant found in this study is different from the red-eye BPH (Mochida, 1970) which showed the egg lethal effect in the red-eye BPH female.     

Metabolic imidacloprid resistance in the brown planthopper,Nilaparvata lugens,relies on multiple P450 enzymes

Target insensitivity contributing to imidacloprid resistance in Nilaparvata lugens has been reported to occur either through point mutations or quantitative change in nicotinic acetylcholine receptors (nAChRs). However, the metabolic resistance, especially the enhanced detoxification by P450 enzymes, is the major mechanism in fields. From one field-originated N. lugens population, an imidacloprid resistant strain G25 and a susceptible counterpart S25 were obtained to analyze putative roles of P450s in imidacloprid resistance. Compared to S25, over-expression of twelve P450 genes was observed in G25, with ratios above 5.0-fold for CYP6AY1, CYP6ER1, CYP6CS1, CYP6CW1, CYP4CE1 and CYP425B1. RNAi against these genes in vivo and recombinant tests on the corresponding proteins in vitro revealed that four P450s, CYP6AY1, CYP6ER1, CYP4CE1 and CYP6CW1, played important roles in imidacloprid resistance. The importance of the four P450s was not equal at different stages of resistance development based on their over-expression levels, among which CYP6ER1 was important at all stages, and that the others might only contribute at certain stages. The results indicated that, to completely reflect roles of P450s in insecticide resistances, their over-expression in resistant individuals, expression changes at the stages of resistance development, and catalytic activities against insecticides should be considered. In this study, multiple P450s, CYP6AY1, CYP6ER1, CYP4CE1 and CYP6CW1, have proven to be important in imidacloprid resistance.     

Functional profiling of the gut microbiomes in two different populations of the brown planthopper,Nilaparvata lugens

Previous studies have demonstrated that gut symbionts are involved in the detoxification metabolism of insect hosts, but the relationship between gut symbionts and host detoxification metabolism of the brown planthopper (Nilaparvata lugens, BPH) remains unclear. In the present study, an indoor population (NlIP) and a field population (NlFP) of the BPH were used to characterize the functional profiling of the gut microbiome based on 16S rDNA sequencing. The results show that the NlIP and NlFP strains of N. lugens had different symbiont compositions, and Proteobacteria, Actinobacteria, and Firmicutes were the dominate phyla, accounting for >75% of the total symbiont compositions. Additionally, the NlIP strain had more Pantoea and Stenotrophomonas, while the NlFP strain showed a higher Wolbachia, Actinobacteria, and Herbaspirillum relative abundance. Furthermore, functional content of the metagenome predicted by PICRUSt demonstrated no significant difference in metagenomic function between the NlIP and NlFP strains in the principal component analysis (PCA), and only three types of genes, namely, genes involved with metabolic diseases, poorly characterized genes, and genes involved in circulatory systems, were different between the strains based on KEGG pathway analysis, which also speculated that gut symbionts are not directly involved in the detoxification metabolism for insecticides in the BPH. These results will be helpful for further research into the mechanisms of gut symbionts involved in detoxification metabolism in the BPH.