莱氏野村菌CQNr01对斜纹夜蛾幼虫的侵染研究

以莱氏野村菌Nomuraea riley CQNr01菌株接种斜纹夜蛾Spodoptera litura 2龄和4龄幼虫,观察感病率,并利用荧光染色观察菌株在幼虫离体表皮上的孢子萌发和附着胞产生情况。结果显示,菌株CQNr01孢子悬液浓度为1×10^8、1×10^9孢子·mL^-1时斜纹夜蛾2龄幼虫的累计死亡率分别为86.58%和89.91%,而4龄则只有13.33%和16.67%。菌株CQNr01的孢子能够成功附着在斜纹夜蛾幼虫的离体表皮上,但孢子在2龄幼虫表皮的粘附能力优于4龄幼虫;接种24 h起两个龄期的离体表皮上均开始有孢子萌发现象并有附着胞和芽管产生,并随着接种时间的增长芽管不断伸长,但相同接种时间下孢子在2龄幼虫表皮上的萌发率和附着胞产生数量明显多于4龄幼虫表皮。研究证明菌株CQNr01对斜纹夜蛾高龄和低龄幼虫的致病力差异显著,其差异主要源于斜纹夜蛾幼虫体壁的屏障作用。     

Antifeedant activity of Jatropha gossypifolia and Melia azedarach senescent leaf extracts on Spodoptera frugiperda (Lepidoptera: Noctuidae) and their potential use as synergists

BACKGROUND: To reduce rates of synthetic insecticide applications, natural product alternatives and synergists are needed. A study has been made of the toxicity of ethanolic senescent leaf extracts (SLEs) of Jatropha gossypifolia and Melia azedarach on larvae of the noctuid pest Spodoptera frugiperda. Their effects as syngergists and inhibitors of several enzyme activities are also reported. RESULTS: When added to the diet, M. azedarach SLE showed lower toxicity than J. gossypifolia SLE. However, after 2 weeks on the diet, the M. azedarach SLE proved to be lethal to 100% of the larval population. Artificial diets with both SLEs have an antifeedant effect on armyworm larvae. Acute toxicity after topical application in a dipping assay was relatively low for both J. gossypifolia and M. azedarach SLEs (LC₅₀ of 2.6 and 1.4 g L^?1, respectively, after 24 h). However, mixtures of the SLEs of M. azedarach and J. gossypifolia had a strong synergistic effect with cypermethrin. Synergism was higher with the J. gossypifolia SLE, perhaps because it contains several natural products with a methylenedioxyphenyl moiety. Both extracts inhibited P450, general esterase and acetylcholinesterase activities in vitro and in vivo. CONCLUSION: Both J. gossypifolia and M. azedarach SLEs are antifeedants to armyworm larvae when present in the food, and also have a synergistic effect with cypermethrin in topical assays. Although the synergistic effect is less than with piperonyl butoxide, both SLEs have some inhibitor activity against detoxification enzymes and acetylcholinesterase. Thus J. gossypifolia and M. azedarach SLEs may be considered as ecofriendly approaches for the control of S. frugiperda in order to reduce cypermethrin usage. Copyright © 2012 Society of Chemical Industry     

Ribavirin, a nucleoside with potential insecticidal activity

BACKGROUND: The triazole-based antiviral nucleoside ribavirin exhibited significant in vitro insecticidal effects against Spodoptera litura, a finding that has prompted further investigations into its in vivo insecticidal properties and mode of action against this insect pest. RESULTS: Ribavirin showed delayed insecticidal effects on third-instar larvae of S. litura at a concentration of 1 mg mL⁻¹. When incorporated into an artificial diet, ribavirin caused various effects, depending on the concentration used. Compared with controls, food intake was lower, larval growth was reduced and larval development prolonged. Pupae weight was reduced, and adult morphology was also affected. Relative to the untreated group, treated groups showed higher mortality at larval and pupal stages, which was generally caused by moult disruption. Results of this study with ribavirin resemble those found in treatment with insect growth regulators. CONCLUSION: This work shows that ribavirin merits further study as a lead compound in a novel class of potential insect control agents or for managing field populations of Lepidoptera pests on cruciferous crops. Copyright © 2012 Society of Chemical Industry     

5种杀虫剂对甜菜夜蛾的室内毒力与田间应用效果评价

通过室内毒力测定和田间药效试验,测定当前5种杀虫剂对甜菜夜蛾的防治效果。结果表明,10%溴虫腈EC对甜菜夜蛾具有优良的防效,药后7 d防效为92.11%,可作为防治甜菜夜蛾的首选药剂;2.5%多杀菌素SC的效果次之,防效为85.49%;2%阿维菌素EC、4.5%高效氯氰菊酯EC和48%乐斯本EC防效稍差,在生产上应慎用。     

红彩真猎蝽对斜纹夜蛾和烟青虫的捕食功能反应

在室内条件下研究了红彩真猎蝽雌成虫对斜纹夜蛾和烟青虫2龄幼虫的捕食作用和种内干扰作用。结果表明,红彩真猎蝽雌成虫的捕食量随着斜纹夜蛾和烟青虫幼虫的密度增加而增大,其捕食功能反应符合Holling II型方程,红彩真猎蝽对斜纹夜蛾2龄幼虫的捕食量符合Na=0.4665Nt/(1+0.0036 Nt),对烟青虫2龄幼虫的捕食量符合Na=0.4275Nt/(1+0.0041Nt)。红彩真猎蝽的捕食作用有较强的种内干扰反应,捕食率与个体间相互干扰的关系符合Hassell模型,红彩真猎蝽的捕食量与害虫密度正相关,寻找效应与害虫密度负相关。     

不同药剂防治花菜甜菜夜蛾的田间药效试验

通过采用20%氯虫苯甲酰胺、10%虫螨腈、24%甲氧虫酰肼和20%氰氟虫腙进行防治花菜甜菜夜蛾药剂筛选试验,结果显示,药后7 d 6个处理4种药剂防效达到最高,均在85%以上,药后10 d各药剂的防效开始降低。各药剂相比,20%氯虫苯甲酰胺的防效最佳,速效性好,持效期长,推荐剂量为7.5 mL/667 m2或10 mL/667 m2,可与20%氰氟虫腙、10%虫螨腈等交替使用。     

甜菜夜蛾与斜纹夜蛾性诱芯田间合用的干扰作用

研究了“并列使用”和“复合使用”方式下甜菜夜蛾(Spodoptera exigua)与斜纹夜蛾(Spodoptera litura)性诱芯在田间合用时的干扰作用.结果表明,甜菜夜蛾与斜纹夜蛾性诱芯联合使用对各自诱捕效果均有明显的干扰作用,相对甜菜夜蛾,斜纹夜蛾受干扰程度较小.甜菜夜蛾单控点处理9月上、中、下旬平均诱蛾量较并列双控点处理分别增加了62.66倍、155.33倍、84.47倍;斜纹夜蛾单控点处理则分别增加了22.40倍、4.05倍、0.36倍,差异极显著;相对复合双控点处理,两单控点的增幅均相对较大.同一监测点上安装两种诱芯,在同一诱捕器中的干扰作用强于分装在不同诱捕器中.     

密度对甜菜夜蛾幼虫色型分化的影响

为明确田间甜菜夜蛾Spodoptera exigua幼虫产生绿色型和黑化型的色型分化原因,在田间系统调查黑化型幼虫所占比例及其与虫口密度的关系,在室内测定不同饲养密度对甜菜夜蛾幼虫色型分化的影响和色型分化敏感龄期,以及视觉、嗅觉和触觉对幼虫色型分化的影响。结果表明,田间甜菜夜蛾1~3龄幼虫均为绿色型,4~5龄幼虫同时存在绿色型和黑化型;在甘蓝上,4龄幼虫中黑化型个体所占比例为21.14%,5龄幼虫中黑色型个体所占比例为28.53%,在辣椒上,4龄幼虫中黑化型个体所占比例为20.54%,5龄幼虫中黑色型个体所占比例为33.88%。随着百株虫量的增加,甘蓝和辣椒上黑化型幼虫所占比例呈现升高趋势。室内研究发现,随着甜菜夜蛾幼虫饲养密度的增加,黑化型幼虫占比显著升高,当饲养密度达到5头/盒时趋于稳定,体色等级指数为3.47; 3龄是甜菜夜蛾幼虫色型分化的敏感龄期;视觉和嗅觉刺激对甜菜夜蛾幼虫黑化无显著影响,而触觉刺激显著促进幼虫黑化,甘蓝叶片碎片和白色聚酯纤维的摩擦处理导致幼虫体色等级指数分别显著升高68.59%和71.79%,表明触觉刺激信号对甜菜夜蛾的密度依赖性黑化有显著促进作用。     

艾法迪悬浮剂防治甜菜夜蛾田间药效试验

研究了24%艾法迪悬浮剂(氰氟虫腙)对奶白菜和结球生菜上甜菜夜蛾的防治效果。试验结果表明,24%艾法迪悬浮剂1000,800,600倍液在药后7d在2种蔬菜上的防效达89.9%～100%,药后14d后在结球生菜上的防效仍达79.6%～100%,且植株叶片未出现药害症状。具有高效、安全、持效期长的优点。     

RSV编码的4种蛋白在“AcMNPV-sf9昆虫细胞”体系中的重组表达

应用反转录聚合酶链式反应(RT-PCR)获得水稻条纹病毒(Rice stripe virus,RSV)的4个基因NS2、NS3、CP和SP,并将它们克隆至pMD-18-T载体上.得到的重组质粒pMD-18-T-NS2、pMD-18-T-NS3、pMD-18-T-CP和pMD-18-T-SP经XbaⅠ/HindⅢ双酶切,分别与经相同方法酶切的苜蓿银纹夜蛾核型多角体病毒(Autographa california nuclear polyhedrosis virus,AcM-NPV)转移载体pFastBacHTb相连接,构建重组转移质粒pFastBacHTb-X(pFastBacHTb-NS2、pFastBacHTb-NS3、pFastBacHTb-CP和pFastBacHTb-SP).序列测定表明,目的基因准确地插入到表达载体中.重组质粒pFastBacHTb-X通过转化包含有穿梭载体的大肠杆菌(Escherichia coli)感受态细胞DH10Bac,得到重组穿梭质粒rb-X(rb-NS2、rb-NS3、rb-CP和rb-SP).rb-X侵染草地贪夜蛾(Spodoptera frugiperda)离体细胞(sf9)24-72 h后,在荧光倒置显微镜可见光200倍视野下观察到细胞增大、培养液和细胞内出现颗粒状物质、部分细胞破裂甚至裂解等一系列与正常sf9细胞形态有明显区别的现象.rb-X侵染细胞72h后,从细胞提取蛋白,电泳分析得到4个条带,大小分别为28.2、29.2、40.2和25.2 ku,与预测的4种融合蛋白大小一致.Western blotting分析分别得到4条单一条带,证明了RSV NS2、NS3、CP和SP基因在"AcMNPV-sf9昆虫细胞"真核表达体系中成功表达.