小菜蛾在春茬甘蓝上的分布及其防治研究

系统调查了小菜蛾在春茬甘蓝不同生育期的分布规律。结果表明,在甘蓝莲座期,小菜蛾的卵主要产在甘蓝近地面的茎部、叶柄和叶背等比较隐蔽的部位,包心初期,大量的小菜蛾幼虫集中在甘蓝的心叶进行为害,进入包心后期,小菜蛾主要在甘蓝的内叶为害,进入收获初期,小菜蛾转移到外叶为害。〖JP2〗据此,甘蓝的包心初期和后期是对小菜蛾进行防治的两个重点时期,结合科学合理施药,在甘蓝的整个生长季节施药2~3次即可有效控制小菜蛾的为害。     

不同性诱产品对小菜蛾诱集效果比较及对其种群动态监测

在北京和上海两地对国内4种小菜蛾性诱剂和国外2种性诱剂的诱捕效果进行了田间试验,并比较了水盆和灯光的诱杀效果。结果表明,中国科学院动物研究所和北京中捷四方有限公司的性诱剂诱杀效果显著优于其他诱芯,两者之间无显著差异（p>0.05）,水盆诱捕效果明显优于灯诱。用筛选的最优诱芯,采用水盆诱集法监测了2007-2010年度北京延庆地区小菜蛾的种群动态,该地区小菜蛾不同年度间种群差异显著,因此,每年和常年监测可为小菜蛾的防治提供更准确的信息。     

苏云金芽胞杆菌Cry1Ba3 蛋白定点突变对杀小菜蛾活性的影响

Cry1Ba3是由本实验室发掘的对小菜蛾有高毒力的杀虫晶体蛋白。为了寻找对杀虫活性有重要影响的氨基酸,为杀虫机理研究和改造杀虫蛋白提供理论依据,本研究利用Ple Bio Informatique Lyonnais数据库对Cry1Ba3的二级结构进行模拟;采用BioEdit软件分析Cry1Ba3的疏水区;将Cry1Ba3与Cry1Aa1、Cry2Aa1、Cry3Aa1以及Cry4Ba1进行多序列比对,从而确定了20个氨基酸突变位点。利用半重叠引物PCR的方法对Cry1Ba3进行定点突变,将突变体在大肠杆菌BL21中进行诱导表达。通过浸叶法对各个突变蛋白杀小菜蛾的生物活性进行测定。获得的20个Cry1Ba3突变体均能在大肠杆菌BL21中表达,并以包涵体形式存在。杀虫活性测定结果表明M6(R192L)、M10(W303A)、M19(H485G)对小菜蛾的活性明显降低,二级结构预测表明活性降低的突变蛋白的构象均发生明显变化,其余17种突变蛋白的活性和二级结构都没有明显变化。说明第192位的精氨酸、第303位的色氨酸和第485位的组氨酸对Cry1Ba3的杀小菜蛾活性有重要影响,上述3个位点氨基酸突变引起的蛋白活性减低可能与毒素的空间结构变化有关。     

多杀菌素对小菜蛾及其天敌的毒力研究

研究评价多杀菌素(菜喜)对小菜蛾及其主要天敌的毒力结果表明,菜喜对小菜蛾具有很高的毒力和良好的田间防治效果,菜喜对青翅蚁型隐翅虫和菜蛾绒茧蜂具有直接杀伤作用,其1000倍稀释液24h使菜蛾绒茧蜂死亡率达62.2%,36h死亡率达88.7%,药液直接处理寄生蜂茧或饲喂均导致很高的死亡率,但对拟环纹狼蛛影响较小。多杀菌素对小菜蛾有很好的控制效果,但对小菜蛾天敌,特别是寄生蜂有相当的负面影响。     

扁蓄提取物对小菜蛾生物活性的影响

研究扁蓄(Polygonum aviculare L.)乙醇提取物对小菜蛾(Plutella xylostella L.)触杀、胃毒、拒食及抑制生长的影响,比较扁蓄不同部位的活性,并对提取溶剂进行选择。结果表明,扁蓄乙醇提取物对小菜蛾的主要作用方式为触杀。     

小菜蛾对阿维菌素和高效氯氰菊酯及其复配剂的抗性

为了评估小菜蛾对阿维菌素和高效氯氰菊酯复配杀虫剂的抗药性风险,采用阿维菌素、高效氯氰菊酯、阿维菌素与高效氯氰菊酯复配剂分别对小菜蛾进行逐代抗性选育至F35代,并在选育过程中对3个小菜蛾抗性品系进行抗性测定。结果表明:小菜蛾阿维菌素抗性品系的抗性指数增长最慢,且趋于平缓,高效氯氰菊酯的抗性增长最快,也最高,抗性达到极高水平,复配剂品系介于两者之间,抗性也达极高水平。     

Synergism and stability of acetamiprid resistance in a laboratory colony of Plutella xylostella

The involvement of metabolic enzymes in the resistance of a laboratory colony of diamondback moth, Plutella xylostella (L), to the neonicotinoid insecticide acetamiprid was determined with the synergists piperonyl butoxide (PBO), which suppresses the activity of cytochrome P-450 monooxygenases, and S,S,S-tributyl phosphorotrithioate (DEF), an inhibitor of esterases, using the leaf-dipping method. Both PBO and DEF enhanced the insecticidal activity of acetamiprid significantly in the resistant P. xylostella strain but not in a reference strain, suggesting that cytochrome P-450 monooxygenases and esterases play an important role in the resistance of P. xylostella to acetamiprid. The resistant P. xylostella strain was also reared without further exposure to acetamiprid to determine the stability of resistance. Maintaining the resistant strain for seven generations in the absence of selection pressure resulted in a drop in resistance ratio from 110 to 2.42, indicating that acetamiprid resistance in P. xylostella is not stable.     

Frequencies of the M918I mutation in the sodium channel of the diamondback moth in China, Thailand and Japan and its association with pyrethroid resistance

In addition to the allele frequencies of the L1014F and T929I mutations which are involved in nerve-insensitive resistance to a pyrethroid, those of the M918I mutation were examined using field strains obtained in China, Thailand, and Japan during 2009-2011. Results show that the resistance allele frequencies at the L1014F site were 89-100%, 97-100% and 65-85%, respectively, for strains in China, Thailand, and Japan. The respective allele frequencies at the T929I site were 86-100%, 70-97% and 58-84% for Chinese, Thai, and Japanese strains. With low frequencies up to 27%, M918I was found in Japan and China, but not in Thailand. The strain homozygous for the M918I and L1014F mutations was established and its resistance level to a pyrethroid was examined. The strain lacks a portion of the sodium channel gene corresponding to the 3′ portion of exon 18a, intron 18, and the 5′ portion of exon 18b. Nevertheless, the strain showed a similar level of resistance to that which was homozygous for the T929I and L1014F mutations.     

小菜蛾为害不同生育期秋甘蓝对产量的影响及经济阈值研究

采用笼罩法测定了小菜蛾在秋甘蓝不同生育期为害造成的产量损失,建立了产量损失率与小菜蛾虫口密度的回归关系式。结果表明,在秋甘蓝苗期、莲座期、结球始期和结球中后期秋甘蓝损失率(y)与小菜蛾虫口密度(x)关系式分别为:y=9.480 6x-2.586 2,y=3.621 8x-0.790 2,y=-0.210 7x2+6.698 1x-1.906 5和y=0.081 1x2-0.147 9x+0.405 4。根据经济阈值模型,秋甘蓝不同生育阶段的小菜蛾幼虫经济阈值分别为苗期0.54头/株,莲座期0.91头/株,结球始期0.67头/株,结球中后期6.08头/株。该研究为秋甘蓝小菜蛾的防治策略和经济阈值的确定提供了科学依据。     

小菜蛾鱼尼丁受体基因克隆及序列分析

利用RT-PCR和RACE技术克隆了小菜蛾(Plutella xylostella)鱼尼丁受体(Px-RyR)基因,其核苷酸序列全长15 748bp,5′非编码区267bp,3′端非编码区109bp,开放阅读区全长为15 372bp(GenBank登录号:JF927788),编码5 123个氨基酸残基。估测其蛋白分子量为579.39ku,等电点为5.45。该基因编码氨基酸序列和其他鳞翅目昆虫RyR氨基酸序列比对相似性较高(92%),与哺乳动物3种亚型RyRs的相似性为45%～47%。此外,二级结构预测,其C-末端存在6个跨膜区域;且Px-RyR中存在一个出现4次重复,长度为89～95个氨基酸的RyR结构域,平均相似性为33%。