宁夏地区烟粉虱对5种常用杀虫剂的抗药性

采用浸叶法分别测定了宁夏8个地区烟粉虱成虫田间种群对4类5种杀虫剂的抗性.结果 表明,供试烟粉虱种群对高效氯氰菊酯已产生了中等至极高水平抗性,抗性倍数为33.31～227.98倍;对烯啶虫胺产生了中等至高水平抗性,抗性倍数为12.14～69.33倍;对毒死蜱和吡虫啉产生了低至中等水平抗性,抗性倍数分别为7.63～38....     

新烟碱类杀虫剂抗药性研究进展

新烟碱类杀虫剂是一类新开发的杀虫剂。研究表明，害虫野外种群对其敏感性差弄较大，现已有多种害虫对吡虫啉和啶虫脒产生了抗性。初步研究显示，马铃薯叶甲对吡虫啉抗性以不完全隐性的常染色体遗传；抗性似不稳定，交互抗性谱随虫种而变化，抗性形成可能与多功能氧化酶和酯酶有关。合理轮用和高剂量杀死策略是治理其抗性的有效措施。     

7种杀虫剂对北京地区烟粉虱成虫毒力的比较研究

本试验比较测定了7种杀虫剂对北京地区烟粉虱成虫的毒力,以期为北京地区高毒农药淘汰提供参考。结果表明:氟虫腈对烟粉虱成虫的毒力最强,其LC50值为2.98(g/mL;新烟碱类杀虫剂啶虫脒、吡虫啉对烟粉虱成虫的生物活性较好,LC50值分别为8.04(g/mL、7.49(g/mL,噻虫嗪对烟粉虱成虫毒力相对较差,LC50值仅为95.03(g/mL;烟粉虱成虫对马拉硫磷、异丙威和噻嗪酮3种杀虫剂不敏感。在北京地区,采用噻虫嗪、马拉硫磷、异丙威和噻嗪酮等杀虫剂,不能有效防治烟粉虱的成虫;氟虫腈、吡虫啉和啶虫脒可以用来防治烟粉虱成虫。     

烟粉虱Q型与B型种群动态及其影响因子研究进展

烟粉虱Bemisia tabaci(Gennadius)是一种重要的农业害虫,并含有许多生物型。其中,烟粉虱Q型和B型是目前研究最为广泛深入的两种生物型。近20年来,烟粉虱B型传入世界各地并暴发成灾,被视为入侵性最强的生物型。相对于烟粉虱B型,烟粉虱Q型是近年来引起人们高度重视的一种新的生物型。在介绍烟粉虱Q型与B型系统发育关系以及基因交流的基础上,着重论述这两种生物型的种群动态及其影响因子的研究进展,以期揭示烟粉虱Q型与B型的成功入侵机制,并为其控制提供依据。     

寄主植物对烟粉虱实验种群的影响

本文探讨了不同寄主植物对烟粉虱种群暴发的影响,在28℃恒温下,组建了烟粉虱在甘蓝、番茄、茄子、烟草、黄瓜、辣椒、西葫芦、青菜等8种不同寄主植物上的实验种群生命表.结果表明:烟粉虱对寄主有较强的选择性.烟粉虱在黄瓜、番茄上的产卵量最大，平均每头雌虫分别达382头和246头。各寄主植物上烟粉虱种群内禀增长率在0.2433～0.3790之间，取食番茄的内禀增长率rm最大，达0.3790，不同寄主植物上烟粉虱内禀增长率大小依次为番茄＞甘蓝＞黄瓜＞西葫芦＞茄子＞烟草＞辣椒＞青菜。保护地蔬菜面积扩大是烟粉虱种群暴发的重要原因之一.     

几种杀虫剂防治烟粉虱药效试验

供试的几种杀虫剂以金好年、莫比朗、阿克泰、科克及蚜虱立克对烟粉虱成虫具有较好的防效,药后3d防效可达89.81%~99.25%。     

华北北部地区棉田烟粉虱成虫季节性动态

1997～2000年对河北省廊坊市棉田烟粉虱季节性种群动态的系统调查表明 ,棉田一般 6月中旬始见烟粉虱成虫 ,轻发生年份烟粉虱成虫数量增长缓慢 ,7月中旬后逐渐减退。严重发生年份(2000年) ,烟粉虱成虫种群数量在棉花生长中前期即持续增长 ,7月下旬进入高峰期 ,棉田烟粉虱成虫数量达百株 3叶2236～8310头 ,8月中旬后逐渐减少。     

几种新型杀虫剂防治B型烟粉虱的药效试验

烟粉虱Bemisia tabaci(Gennadius),又称甘薯粉虱、棉粉虱,是热带和亚热带地区的重要害虫之一。该虫可危害棉花、蔬菜和园林花卉等植物,并且能传播双生病毒,平均每年在     

6种杀虫剂防治烟地烟粉虱试验

为了筛选控制烟地烟粉虱的有效药剂,采用6种杀虫剂对烟地烟粉虱进行田间药效试验。结果表明,在烟粉虱发生盛期,施一次药,药后7 d,7.5%鱼藤酮乳油对烟粉虱的防治效果最好,为78.30%,3%啶虫脒乳油、5%阿维菌素乳油对烟粉虱的防治效果分别达到69.69%和67.54%,这3种药剂的持效期可达7~10 d,防治效果和持效期都显著高于0.6%苦参碱水剂和0.5%印楝素乳油2种药剂。建议在生产上采用7.5%鱼藤酮乳油、3%啶虫脒乳油及5%阿维菌素乳油等按常规用量在烟粉虱发生期进行喷雾,可有效控制烟粉虱的为害。     

不同寄主作物烟粉虱种群数量的研究

采用等距机械抽样法对棉花、茄子、豇豆等不同作物上烟粉虱成虫、蛹、卵的种群数量进行调查,并对其空间分布进行分析。结果表明,在茄子叶片上烟粉虱成虫和蛹的数量最多,豇豆叶片上卵的数量最多。棉花上烟粉虱成虫种群的空间分布呈聚集型,蛹、卵的种群为均匀分布,茄子上烟粉虱成虫和蛹为均匀分布,卵呈聚集分布;豇豆上烟粉虱成虫为均匀分布,蛹和卵为聚集分布。     

Age-specific expression of resistance to a neonicotinoid insecticide in the whitefly Bemisia tabaci

Neonicotinoid insecticides retain a crucial role within many chemical and integrated control strategies for the tobacco whitefly, Bemisia tabaci Gennadius, in spite of the establishment of potent and widespread resistance in many areas. Metabolic resistance mechanisms mediated by overexpression of P450-dependent monooxygenases have been implicated in neonicotinoid resistance in the two most prevalent B. tabaci biotypes. Further characterisation of resistance to the neonicotinoid imidacloprid in populations of both these B- and Q-types is reported.Expression of resistance to imidacloprid was age specific in B- and Q-type strains of B. tabaci. The highest observed resistance ratio at LC(50) expressed in prepupal nymphs was 13, compared with at least 580 in their adult counterparts. For all strains, resistance expressed in immatures was not sufficiently potent to compromise recommended imidacloprid application rates.Targeting neonicotinoids towards immature life stages of B. tabaci may circumvent the protection conferred by current mechanisms of resistance, simultaneously reducing the selection pressures imposed. However, such tactics may enhance the expression of existing resistance mechanisms in immatures, or promote the establishment of novel ones expressed in all life stages.     

Cotton whitefly (Bemisia tabaci) resistance to organophosphate and pyrethroid insecticides in Pakistan

Resistance to three organophosphate and four pyrethroid insecticides was monitored from 1992 to 2000 in field populations of adult whiteflies, Bemisia tabaci, from Pakistan using a leaf-dip method. There was generally a very high resistance to dimethoate and deltamethrin, and a moderate resistance to monocrotophos during 1992 to 1996. From 1997 to 2000, resistance to these insecticides dropped to low levels because of less reliance on them for whitefly control, and introduction of new chemistries with novel modes of action that had no cross-resistance to conventional insecticides. Concurrently, whitefly resistance to acephate, fenpropathrin, lambda-cyhalothrin and bifenthrin mostly remained low. An insecticide resistance management strategy is recommended that particularly emphasizes the rotation of still-effective insecticides from different chemical classes along with the use of novel chemicals and other tactics of integrated pest management.     

Biotype and insecticide resistance status of the whitefly Bemisia tabaci from China

BACKGROUND: Resistance to numerous insecticide classes in Bemisia tabaci Gennadius has impaired field control efficacy in south‐eastern China. The biotype and resistance status of B. tabaci collected from these areas was investigated. RESULTS: Two different biotypes of B. tabaci (B‐biotype and Q‐biotype) were detected in south‐eastern China, and the samples collected from geographical regions showed a prevalence of the Q‐biotype and the coexistence of B‐ and Q‐biotypes in some regions. Moderate to high levels of resistance to two neonicotinoids were established in both biotypes (28–1900‐fold to imidacloprid, 29–1200‐fold to thiamethoxam). Medium to high levels of resistance to alpha‐cypermethrin (22–610‐fold) were also detected in both biotypes. Four out of 12 populations had low to medium levels of resistance to fipronil (10–25‐fold). Four out of 12 populations showed low levels of resistance to spinosad (5.7–6.4‐fold). All populations tested were susceptible to abamectin. CONCLUSION: The Q‐biotype B. tabaci is supplanting the B‐biotype which used to be ubiquitous in China. Field populations of both B‐ and Q‐biotypes of B. tabaci have developed high levels of resistance to imidacloprid and thiamethoxam. Abamectin is the most effective insecticide against adult B. tabaci from all populations. Copyright © 2010 Society of Chemical Industry     

Susceptibility to insecticides in the Q biotype of Bemisia tabaci is correlated with bacterial symbiont densities

BACKGROUND: The presence of symbiotic microorganisms may influence an insect's ability to tolerate natural and artificial stress agents such as insecticides. The authors have previously shown that Rickettsia in the B biotype of the whitefly Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) increases this insect's susceptibility to several insecticidal compounds. This communication reports a comparison of the susceptibilities of three isofemale strains of the Q biotype of B. tabaci harbouring different bacterial complements to major insecticides from different chemical groups: one strain harboured only Arsenophonus, one harboured Rickettsia and Arsenophonus and one harboured Arsenophonus and Wolbachia. RESULTS: The presence of different symbiont combinations in the three strains had a significant influence on their susceptibility to most of the insecticides tested. Thiamethoxam, imidacloprid, pyriproxyfen and spiromesifen had a significant influence on strains that had the double infections Rickettsia–Arsenophonus and Wolbachia–Arsenophonus, which also carried higher amounts of symbionts as assessed by quantitative real‐time PCR. No significant differences in mortality rates were observed when the tested strains were treated with diafenthiuron. CONCLUSION: The results suggest a correlation between the presence of high bacterial densities in B. tabaci and the insect's ability to detoxify toxic compounds such as insecticides. Copyright © 2009 Society of Chemical Industry     

烟粉虱在山东烟区的发生动态及为害调查

本文调查了烟粉虱在山东烟田的发生动态和在不同县(市)的发生为害情况,结果表明:烟田烟粉虱成虫的发生动态年度之间大致相同,每年5月底6月初田间开始出现成虫,至7月下旬烟粉虱成虫发生量达到高峰,持续到8月份仍为害较重。烟粉虱在山东省主产烟区均有发生为害,并且不同产区其发生程度不尽相同,且各县(市)主栽品种烟粉虱的发生程度有一定差异。     

Development of a low-density DNA microarray for diagnosis of target-site mutations of pyrethroid and organophosphate resistance mutations in the whitefly Bemisia tabaci

BACKGROUND: Rapid and accurate detection of mutations related to insecticide resistance is essential for development of resistance management strategies to support sustainable agriculture. The M918V, L925I and T929V mutations of the voltage‐gated sodium channel gene (vgsc) and the F392W mutation of the acetylcholinesterase I gene (ace1) are reportedly associated with resistance to pyrethroids and organophosphates, respectively, in Bemisia tabaci. In order to detect known base substitutions in the ace1 and vgsc genes, a low‐density microarray with an allele‐specific probe was developed. RESULTS: Specific regions of the ace1 and vgsc gene mutations were amplified by multiplex asymmetrical PCR using Cy3‐labelled primers, and then the PCR products were hybridised on the microarray. After analysing the probe signal data, the microarray containing 12 allele‐specific probes produced a unique pattern of probe signals for field DNA samples of B. tabaci. To determine the optimal cut‐off value of each probe, receiver operating characteristic (ROC) curve analysis was conducted using SPSS. Among 60 individual samples, microarray data for 57 samples were consistent with direct sequencing data. CONCLUSION: Although many molecular detection methods have been employed to monitor insecticide resistance, the present microarray provides rapid and accurate identification of target mutations in B. tabaci for resistance management. Copyright © 2011 Society of Chemical Industry     

Monitoring neonicotinoid resistance in biotype B of Bemisia tabaci in Florida

BACKGROUND: Biotype B of the sweetpotato whitefly, Bemisia tabaci (Genn.), is a worldwide pest that has developed resistance to many insecticides, including the neonicotinoid class. Florida field populations were monitored for susceptibility to the neonicotinoids imidacloprid and thiamethoxam using a cut leaf petiole bioassay method. RESULTS: Average RR₅₀ values for imidacloprid increased from 3.7 in 2000 to 12.0 in 2003; decreased to 5.0 and 2.5 in 2004 and 2005, respectively; and then increased to 26.3 and 23.9 in 2006 and 2007, respectively. Populations with RR₅₀ values of about 50 to 60 during generation one reverted to RR₅₀ values of ?4 in six generations, when reared without further exposure to imidacloprid. Average RR₅₀ values for thiamethoxam increased from 2.0 in 2003 to 24.7 in 2006 and decreased to 10.4 in 2007. Populations with RR₅₀ values of about 22, 32 and 53 during generation one declined to 8, 5 and 6, respectively, after being reared for five generations without exposure to thiamethoxam. The correlation coefficient from the 26 populations that were bioassayed both with imidacloprid and thiamethoxam showed a significant positive correlation (R² = 0.58) between these populations. CONCLUSION: The high level of RR₅₀ values to imidacloprid and thiamethoxam suggest an unstable decline in the susceptibility of B. tabaci to imidacloprid and thiamethoxam, with possible cross‐resistance or predisposition for dual resistance selection. Copyright © 2009 Society of Chemical Industry     

Toxicity of spiromesifen to the developmental stages of Bemisia tabaci biotype B

BACKGROUND: Spiromesifen is a novel insecticidal/acaricidal compound derived from spirocyclic tetronic acids that acts effectively against whiteflies and mites via inhibition of acetyl‐CoA‐carboxylase, a lipid metabolism enzyme. The effects of spiromesifen on the developmental stages of the whitefly Bemisia tabaci (Gennadius) were studied under laboratory conditions to generate baseline action thresholds for field evaluations of the compound. RESULTS: Adult B. tabaci mortality rate after spiromesifen treatment (5 mg L^?1) was 40%. Treatment with 0.5 mg L^?1 reduced fecundity per female by more than 80%, and fertility was almost nil. LC₅₀ for eggs was 2.6 mg L^?1, and for first instar 0.5 mg L^?1. Scanning electron microscopy revealed that eggs laid by treated adult females had an abnormally perforated chorion, and females were unable to complete oviposition. Light and fluorescent microscopy showed significantly smaller eggs following treatment, and smaller, abnormally formed and improperly localized bacteriomes in eggs and nymphs. The number of ovarioles counted in females treated with 5 mg L^?1 was significantly reduced. Spiromesifen showed no cross‐resistance with other commonly used insecticides from different chemical groups, and resistance monitoring in Israel showed no development of field resistance to this insecticide after 1 year of use. CONCLUSION: The strong effect on juvenile stages of B. tabaci with a unique mode of action and the absence of cross‐resistance with major commonly used insecticides from different chemical groups suggest the use of spiromesifen in pest and resistance management programmes. Copyright © 2008 Society of Chemical Industry     

Biochemical and molecular mechanisms of diafenthiuron resistance in the whitefly,Bemisia tabaci

B-biotype Bemisia tabaci has developed high levels of resistance to many insecticides. To investigate the risks and explore possible mechanisms of resistance to diafenthiuron in B. tabaci, a 32.8-fold diafenthiuron-resistant strain (R-DfWf) was established after selection for 36 generations compared with the susceptible strain (S-Lab). Biochemical assays showed that the activity of cytochrome P450 towards p-NA was significantly higher (4.37-fold higher) in the R-DfWf strain than in the S-Lab strain. Similarly, the carboxylesterase (COE) activity and glutathione S-transferase (GST) activity were also significantly higher (3.12- and 1.83-fold higher, respectively) in the R-DfWf strain than in the S-Lab strain. The expression of five of seven P450 genes was significantly higher (>3-fold) in the R-DfWf strain than in the S-Lab strain. The expression of COE2 was significantly higher (>2.5-fold) in the R-DfWf than in the S-Lab strain. The expression of GST and GST2 was significantly higher (>2.3-fold) in the R-DfWf than in the S-Lab. Thus, cytochrome P450, COE and GST may appear to be responsible for the resistance to diafenthiuron in B. tabaci. It is also valuable for usage of insecticides for resistance management and control of this species.