Stability and Biological Activity of Cyfluthrin Isomers

A GC-MS method capable of completely separating the four pairs of diastereoisomers of cyfluthrin is presented and the method used to show that isomerisation of the cyfluthrin enantiomers occurs in methanol. This methanol-induced isomerisation could also be demonstrated by bioassays using water fleas. The biological activities of the various cyfluthrin isomers contained in the commercial products cyfluthrin and beta-cyfluthrin were assayed using several strains of lepidopteran larvae including Plutella xylostella, Heliothis virescens and Spodoptera frugiperda. With the susceptible strains, the efficiencies of the isomers mixtures of cyfluthrin and beta-cyfluthrin were shown to obey the rules of additivity. However, in tests with a resistant strain of P. xylostella originating from Thailand, the ‘inactive’ isomer III acted synergistically with the active isomer IV. Resistance factors in strains of H. virescens and P. xylostella were found to be higher with cis than with trans isomers. This probably contributes to the superior action of cyfluthrin and beta-cyfluthrin against various pests of agricultural importance since the commercial products contain a high content of trans isomers (‘high trans pyrethroids’).     

草地贪夜蛾与玉米灌浆期3种常见夜蛾科害虫的形态特征比较

草地贪夜蛾Spodoptera frugiperda(J. E. Smith)是全球预警的一种重大迁飞性农业害虫。2019年1月入侵我国,目前已扩散蔓延至我国24个省份。田间调查发现,在玉米灌浆期,草地贪夜蛾与黏虫Mythimna separata(Walker)、劳氏黏虫Leucania loreyi(Duponchel)和棉铃虫Helicoverpa armigera(Hübner)等夜蛾科害虫常常混合发生,且形态相近,容易混淆,给调查和测报工作带来很大困难。本文详细描述了草地贪夜蛾卵、幼虫、蛹和成虫的外部形态特征,比较了其与黏虫、劳氏黏虫和棉铃虫4个虫态在形态特征上的差别,以期为玉米灌浆期草地贪夜蛾的准确鉴别和田间调查提供依据,并为其精准测报奠定基础。     

白僵菌和绿僵菌对棉铃虫的室内防控效果评价

【目的】研究白僵菌和绿僵菌在不同侵染方式下对棉铃虫幼虫致死效应的差异。【方法】室内配置不同浓度白僵菌和绿僵菌孢悬液,采用浸渍法和饲喂法对棉铃虫三龄幼虫进行处理,统计死亡率及体重。【结果】白僵菌和绿僵菌孢子悬浮液经体壁侵染对棉铃虫最大校正死亡率分别为63%和73%,经消化道侵染对棉铃虫最大校正死亡率为38%和65%,与对照相比,体重有不同程度的下降。【结论】室内条件下白僵菌和绿僵菌两者的分生孢子悬浮液均是,浓度越高对棉铃虫的致死效率和体重控制效果越好,且4×10⁷ 孢子 /mL浓度的绿僵菌和1.5×10⁸ 孢子/mL的白僵菌是防治棉铃虫幼虫的经济有效浓度。     

棉铃虫膨胀线粒体基因组的鉴定与分析

以已公布的棉铃虫线粒体DNA序列对来自4头棉铃虫雄蛹的DNA的三代测序数据进行筛选,获得了11条与线粒体DNA有同源性的三代read序列,并根据其中的read 66003鉴定出了一种膨胀的线粒体基因组。该线粒体基因组大小为27 113 bp,其保守区域包含13个蛋白编码基因、2个rRNA基因、22个tRNA基因以及1个AT富集区,与已公布的棉铃虫线粒体基因组的结构相似。膨胀区域位于cox1基因编码区内部,大小为11 467 bp,经预测含有一个完整的真核基因(依赖ATP的RNA解旋酶)以及多种转座元件的片段,但与线粒体DNA无同源性,也无I类或Ⅱ类内含子存在的证据。对田间和室内棉铃虫DNA样品的PCR扩增未能检测到膨胀线粒体基因组的存在。以上结果表明膨胀片段可能是细胞核DNA序列通过偶然的水平转移事件而整合到线粒体基因组中的,且该种膨胀方式的发生概率极低。本文报道的膨胀线粒体基因组为日后动物线粒体基因组学的研究提示了一种独特的变异方式。     

甲氨基阿维菌素苯甲酸盐对3种鳞翅目害虫与赤眼蜂的毒力

摘 要：为明确甲氨基阿维菌素苯甲酸盐对甘肃河西地区3种玉米害虫和松毛虫赤眼蜂的毒力,协调甘肃河西地区化学防治和生物防治之间的矛盾,本研究在室内采用饲喂法和药膜法分别对棉铃虫、亚洲玉米螟、粘虫和松毛虫赤眼蜂进行毒力测定。结果表明,随着甲氨基阿维菌素苯甲酸盐浓度增加,4种昆虫的校正死亡率均呈递增趋势,当药剂浓度达0.500 mg/L时,4种昆虫的校正死亡率均达95%以上。致死中浓度表明,甲氨基阿维菌素苯甲酸盐对松毛虫赤眼蜂毒力最高,致死中浓度LC50为0.078 mg/L,其次依次为亚洲玉米螟、棉铃虫和粘虫,致死中浓度LC50依次为0.109、0.120、0.127 mg/L。甲氨基阿维菌素苯甲酸盐对松毛虫赤眼蜂的毒力是其他3种鳞翅目昆虫的1.40~1.63倍。因此,综合防治中使用甲氨基阿维菌素苯甲酸盐防治害虫时,应避开赤眼蜂的出蜂时期,以降低化学杀虫剂对赤眼蜂的杀伤作用。     

The Post-exposure Effects of Spinosad and Plant Allelochemicals on Biological Characteristics of Helicoverpa armigera (Lepidoptera:Noctuvidae)

In order to define the combined effects of spinosad and plant allelochemicals on Helicoverpa armigera(Lepidoptera:Noctuvidae), the research fed them on artificial diets with different doses of spinosad, gossypol, quercetin and tannicacid, and the changes of pupal and imaginal biological characteristics were observed and recorded. The results showed that spinosad at sublethal concentrations decreased pupation ratio and pupal weight, prolonged prepupal and pupal periods, and decreased emergence ratio, fecundity and longevity of adults. Combined with plant allelochemicals, spinosad significantly prolonged pupal period and shorten adult longevity. Other life-cycle parameters such as pupation ratio, pupal weights, emergence ratio, eggs laid per female and hatch ratio did not change significantly. The results clearly indicated that plant allelochemicals did not change spinosad efficiency on H. armigera, but the combination of spinosad and plant allelochemicals might affect pest population dynamics significantly by changing its development.     

取食Bt蛋白对棉铃虫和斜纹夜蛾幼虫爬行能力的影响

为研究Bt棉田靶标害虫棉铃虫和非靶标害虫斜纹夜蛾的爬行规律及Bt蛋白对其爬行能力的影响,采用TrackSphere LC-100昆虫行为记录仪分别进行测定。结果表明:随着龄期的增加,棉铃虫幼虫停留次数逐渐增加,且幼虫在白天的活动能力显著高于晚上,而斜纹夜蛾则相反,随着龄期的增加,斜纹夜蛾幼虫的停留次数逐渐减少,同时幼虫在各时间段之间的差异也逐渐显著。用Bt棉或Bt蛋白饲喂2种幼虫发现,Bt蛋白对棉铃虫爬行能力的影响显著大于斜纹夜蛾,这种影响主要集中在低龄段,且一定浓度阈值范围内Bt蛋白对棉铃虫和斜纹夜蛾的爬行能力具有促进作用,超过此阈值范围其促进作用开始转化为抑制。结果为进一步了解棉铃虫和斜纹夜蛾幼虫爬行规律,研究Bt棉对棉铃虫的控制作用及次要害虫斜纹夜蛾的再度猖獗原因提供重要科学依据。     

寄主大小棉铃虫齿唇姬蜂产卵和发育的关系

以在27℃下、室内人工饲养的棉铃早和棉铃早齿蜃 为材料，研究了寄主大小对棉铃虫齿唇姬蜂产卵和生长发育的影响。结果表明，寄主大小对雌蜂产卵有显著的影响。寄生率随寄主体重增加而降低，在被寄生产卵的棉铃虫幼虫中，体重小于18mg的占92％，大于18mg的幼虫不适宜该寄生蜂产卵；人工饲料上饲养的棉铃虫幼虫，自孵化后的136h为适合被寄生的时段，对数据的相关和回归分析表明，寄主寄生时体重与蜂近似幼虫体重、蜂近似幼虫体重与成蜂体重均呈显著的正相关，尤其在雌蜂上表现得更为显著；成蜂在一定的范围内，体重越大，寿命越长，体重过大或过小，寿命均有下降的趋势，寄主大小对的发育历期无显著影响。