Selection of global Metarhizium isolates for the control of the rice pest Nilaparvata lugens (Homoptera: Delphacidae)

BACKGROUND: This study was initiated to search for fungal candidates for microbial control of brown planthopper (BPH) Nilaparvata lugens Stål, to which little attention has been paid in the past two decades. RESULTS: Thirty‐five isolates of Metarhizium anisopliae (Metschnikoff) Sorokin and M. flavoviride Gams & Rozsypal from different host insects worldwide were bioassayed for their lethal effects against third‐instar BPH nymphs at 25 °C and a 14:10 h light:dark photoperiod at ca 1000 conidia mm^?2. On day 9 post‐treatment, mortality attributable to mycosis ranged from 6.5 to 64.2% and differed significantly among the tested isolates with no apparent relationship to their host origin. Only two BPH‐derived M. anisopliae isolates from the Philippines (ARSEF456) and Indonesia (ARSEF576) killed > 50% of the nymphs. Both isolates were further bioassayed for time–concentration–mortality responses of the nymphs to the sprays of 19–29, 118–164 and 978–1088 conidia mm^?2 in repeated bioassays. The resultant data fitted a time–concentration–mortality model very well. Their LC₅₀ values were estimated as 731 and 1124 conidia mm^?2 on day 7 and fell to 284 and 306 conidia mm^?2, respectively, on day 10. CONCLUSION: The two M. anisopliae isolates are potential biocontrol agents of BPH for further research. This is the first report of the lethal effects of global Metarhizium isolates on the rice pest. Copyright © 2008 Society of Chemical Industry     

Possible connection between imidacloprid-induced changes in rice gene transcription profiles and susceptibility to the brown plant hopper Nilaparvatalugens Stål (Hemiptera: Delphacidae)

The chemical pesticide, imidacloprid (IMI) has long-lasting effectiveness against Hemiptera. IMI is commonly used to control the brown planthopper (BPH), Nilaparvata lugens Stål (Hemiptera: Delphacidae). Some chemical pesticides, however, can induce the susceptibility of rice to BPH, which has indirectly led to the resurgence of BPH. The mechanism of the chemical induction of the susceptibility of rice to BPH was not previously understood. Here, a 44 K Agilent Rice Expression Microarray was used to identify changes in gene expression that accompany IMI-induced rice susceptibility to BPH. The results showed that 225 genes were differentially expressed, of which 117 were upregulated, and 108 were downregulated. Gene ontology annotation and pathway analysis revealed that differentially expressed genes were mainly classified into the eight functional groups: oxidation reduction, regulation of cellular process, response to stress, electron carrier activity, metabolic process, transport, signal transducer, and organismal development. The genes encoding plant lipid transfer protein, lignin peroxidase, and flavonol-3-O-methyltransferenase may be important responses to the IMI-induced susceptibility of rice to BPH. The reliability of the microarray data was verified by performing quantitative real-time PCR and the data provide valuable information for further study of the molecular mechanism of IMI-induced susceptibility of rice.     

Inheritance mode and realized heritability of resistance to imidacloprid in the brown planthopper,Nilaparvata lugens (Stål) (Homoptera: Delphacidae)

BACKGROUND: The brown planthopper, Nilaparvata lugens (Stål), is a serious pest that causes enormous losses to the rice crop in Asia. The genetic basis of imidacloprid resistance was investigated in N. lugens. RESULTS: The resistant strain, selected for imidacloprid resistance from a field population of N. lugens collected from Nanjing, Jiangsu Province, China, showed a 964‐fold resistance compared with the laboratory strain. Progenies of reciprocal crosses (F₁ and F₁′) showed similar dose–mortality responses (LC₅₀) to imidacloprid, and also exhibited a similar degree of dominance (D), 0.58 for F₁ and 0.63 for F₁′. Chi‐square analyses of self‐bred and backcross progenies (F₂, F₂′ and BC respectively) rejected the hypothesis for a single gene control of the resistance. The estimated realized heritability (h²) of imidacloprid resistance was 0.1141 in the resistant strain of N. lugens. CONCLUSION: The results showed that imidacloprid resistance in N. lugens was autosomal and was expressed as an incompletely dominant trait, probably controlled by multiple genes. Copyright © 2009 Society of Chemical Industry     

杀菌剂与吡虫啉混合配剂对褐飞虱种群增长的影响

褐飞虱Nilaparvata lugens Stål是亚洲国家水稻产区的主要害虫,其腹部脂肪体内存在大量类酵母共生菌（Yeast-like symbiotes,YLS）。YLS对褐飞虱的生长发育和繁殖起着至关重要的作用。以YLS为靶标,通过抑制褐飞虱体内YLS从而控制褐飞虱的发生必将是今后有效防治褐飞虱的新途径。前期研究表明,与单一的化学杀虫剂相比,杀虫剂和杀菌剂的混配制剂因能有效抑制褐飞虱体内YLS的数量从而导致褐飞虱更高的死亡率。本研究利用生命表和Morris-Watt数学模型分析了27%丰加霉素&四霉素P&四烯菌素B&四霉素A和75%肟菌酯&戊唑醇分别与吡虫啉的混合配剂对褐飞虱种群增长影响。结果表明,2种混合配剂处理后褐飞虱体内YLS的数量均明显下降,且褐飞虱种群增长指数显著低于吡虫啉处理组,混合配剂对褐飞虱的抑制作用主要表现在卵孵化期和成虫产卵期。本研究结果为褐飞虱防治提供了新的思路和方法。     

水稻瘤矮病毒介导的转cry1Ab水稻对褐飞虱种群的影响

在人工气候室条件下,以抗虫转cry1Ab水稻（MF86）及其亲本对照非转基因水稻闽恢3301（MH3301）为材料,利用年龄-龄期两性生命表,研究水稻瘤矮病毒介导的转cry1Ab水稻对非靶标害虫褐飞虱种群的影响。研究结果表明,感病水稻对取食MH3301的褐飞虱种群寿命影响不显著,促进了其生殖力;而显著缩短了取食MF86的褐飞虱寿命,降低了其生殖力。水稻在不感病的情况下,取食MF86较取食MH3301的褐飞虱种群可显著延长寿命和提高生殖力;而水稻在感病的情况下,取食MF86较取食MH3301的褐飞虱种群生殖力显著降低。感病的MF86较未感病MF86显著降低褐飞虱的内禀增长率、周限增长率,显著缩短世代平均周期;而感病的MH3301较未感病MH3301对褐飞虱生命表动态参数的影响基本均不显著。由此可见,水稻瘤矮病毒介导的转cry1Ab水稻（MF86）对褐飞虱种群增殖具有显著的负面影响。     

褐飞虱自噬相关基因NlATG4的表达与功能

ATG4是一种半胱氨酸蛋白酶,负责ATG8蛋白羧基末端的切割,在自噬体形成过程中发挥重要作用。本研究克隆得到褐飞虱ATG4基因（NlATG4）的cDNA全长序列（GenBank登录号:MF062502.1）。RT-qPCR分析结果表明,NlATG4基因在褐飞虱的若虫和成虫时期均有表达,1～2龄若虫的表达量最高,在其他发育阶段的表达量稍低。RNAi结果显示,在dsRNA注射后的第4d,靶标基因NlATG4的表达量显著下降（仅为dsGFP对照组的22%）,同时,NlATG4的RNA干扰导致虫体ATP含量显著降低,仅为1.0μmol/(L·mg蛋白-1),为对照组的25%;在注射后的第6d,dsNlATG4处理组的褐飞虱存活率出现显著降低,其脂肪体组织变得松散,大型脂滴（直径≥5.0μm）数量增多,类酵母共生菌周围泡状结构的界限基本消失;在注射后的第8 d,dsNlATG4处理的褐飞虱的存活率下降为36.7%,比dsGFP对照组的存活率下降53.3%。本研究表明靶向NlATG4基因的RNA干扰会破坏褐飞虱脂肪体的结构完整性和类酵母共生菌的微环境,影响脂类物质代谢和ATP含量,并导致褐飞虱存活...     

转cry30Fa1水稻对褐飞虱NlHRP基因表达模式的影响

转cry30Fa1水稻（KF30-14）会显著控制褐飞虱Nilaparvata lugens (Stål)种群数量增长,但其影响机制尚不清楚。本研究利用相关转录组数据分析筛选获得了一个表达量有显著差异的基因NlHRP,并克隆了该基因。序列分析表明,NlHRP编码了一个富组氨酸蛋白,无保守结构域。通过实时荧光定量PCR检测羽化24、72、96 h的褐飞虱雌虫的NlHRP表达量,结果显示该基因在KF30-14褐飞虱实验种群中的表达量均高于MH86实验种群,且在羽化72 h时,达到显著差异;对羽化后72 h褐飞虱雌虫的头、胸、卵巢、中肠、脂肪体的NlHRP表达量检测发现,NlHRP在褐飞虱的头、胸、中肠表达量较高,其中KF30-14褐飞虱实验种群雌虫的NlHRP在头部表达量显著升高。推测NlHRP可能与褐飞虱适应转cry30Fa1水稻的抗性有关,该研究结果为揭示转cry30Fa1水稻抗褐飞虱的分子机制提供相关基础。     

Evaluation of fipronil nanoformulations for effective management of brown plant hopper (Nilaparvata lugens) in rice

In this paper, we report the development, characterization and bioefficacy evaluation of fipronil nanoformulations against brown plant hopper (BPH); Nilaparvata lugens in rice. Nanoformulations were characterized for nanosizing and stability under variable conditions. Bioefficacy of nanoformulations were evaluated under field condition at farms of Indian Agricultural Research Institute, New Delhi during Kharif 2015. At milking stage BPH populations were above economic threshold level; followed by foliar application of fipronil nanoformulations at four doses (viz., 30, 45, 60 and 90 g a.i./ha) along with commercial formulation of fipronil. The mean mortality clearly indicated that all the insecticidal treatments were significantly superior over untreated control where, highest mortalities were observed in nanodispersions followed by monolithic dispersion and commercial formulation of fipronil. Treated plots 7 days after application @ 60 g a.i./ha has shown 93.47%, 86.89% and 80.47% reduction BPH population in nanodispersion, encapsulated monolithic dispersion and commercial formulation treated plots respectively. In comparison to commercial formulation @ 60 g a.i./ha yield has increased by 0.56 t ha^?1 (28.76%) and 0.26 t ha^?1 (14.04%) in nanodispersion and monolithic dispersion.     

以降低稻田生态系统脆弱性为主旨的褐飞虱综防措施

稻田生态系统是一种需要人工干预的开放系统,其多样性较低,营养结构简单,空白生态位较多,本身具有一定的脆弱性,加之近年来耕作方式的转变,农药化肥的不合理使用等,使其脆弱性增加,更容易受到害虫的攻击。褐飞虱作为水稻主要害虫之一,在对其进行防治时要充分发挥稻田生态系统内各物种间的调节作用,可持续地抑制其暴发危害。本文结合我们以及广东的工作实践,综述了以降低稻田生态系统脆弱性为主旨的褐飞虱综防措施,包括丰产控害栽培防治、高效低毒的化学药剂防治、物理防治、生物防治以及饱和生态位调控防治。     

药用野生稻与栽培稻抗褐飞虱HPLC指纹图谱的比较

应用高效液相色谱技术,研究比较了栽培稻与广西药用野生稻的抗褐飞虱HPLC指纹图谱。结果表明,药用野生稻指纹图谱中既含有与栽培稻抗褐飞虱生物型II相关的峰1、峰2、峰8,又含有与栽培稻抗褐飞虱孟加拉型相关的峰3、峰5、峰9、峰11,但药用野生稻中的峰1、峰2、峰3、峰5的含量特别高。前期的结果表明,峰4与栽培稻对褐飞虱孟加拉型的抗性呈负相关,峰12与栽培稻对褐飞虱两种生物型的抗性均呈负相关,但广西药用野生稻却几乎不含峰4和峰12。广西药用野生稻的这种既与栽培稻相似,又有它自己鲜明特点的HPLC指纹图谱特征,使它对褐飞虱具有广谱抗性。     

Insecticidal spider venom toxin fused to snowdrop lectin is toxic to the peach-potato aphid, Myzus persicae (Hemiptera: Aphididae) and the rice brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae)

The SFI1/GNA fusion protein, comprising of snowdrop lectin (Galanthus nivalis agglutinin, GNA) fused to an insecticidal spider venom neurotoxin (Segestria florentina toxin 1, SFI1) was tested for toxicity against the rice brown planthopper Nilaparvata lugens (Stål) and the peach‐potato aphid Myzus persicae (Sulzer) by incorporation into artificial diets. Significant effects on the mortality of N. lugens were observed, with 100% of the insects fed on the SFI1/GNA fusion protein diet dead by day 7. The survival of the aphid M. persicae was also reduced when fed on the SFI1/GNA fusion protein. After 14 days, only 49% of the aphids that were fed on the fusion protein were still alive compared with approximately 90% of the aphids fed on the control diet or on diet containing GNA only. The SFI1/GNA fusion protein also slowed the development of M. persicae, and the reproductive capacity of the aphids fed on the SFI1/GNA fusion protein was severely reduced. The ability of GNA to act as a carrier protein, and deliver the SFI1 neurotoxin to the haemolymph of N. lugens, following oral ingestion, was investigated. The successful delivery of intact SFI1/GNA fusion protein to the haemolymph of these insects was shown by western blotting. Haemolymph taken from the insects that were fed on the fusion protein contained two GNA‐immunoreactive proteins of molecular weights corresponding to GNA and to the SFI1/GNA fusion protein. © 2005 British Crown Copyright. Published for SCI by John Wiley & Sons, Ltd.