氟啶脲防治烟草甲的研究

本文通过室内及现场试验,研究氟啶脲防治烟草甲的效果。试验结果表明,烟草甲人工饲料中氟啶脲的浓度为4mg/kg时,烟草甲2龄幼虫的校对死亡率可达97.33%;对库存烟叶,当烟叶中氟啶脲的浓度为8～16mg/kg时,对烟草甲防治效果达到100%,并有24个月的防治作用。     

三种杀虫剂对皂角豆象的致死效果

【目的】筛选对皂角豆象Megabruchidius dorsalis(Fahraeus)致死效果最好的杀虫剂。【方法】采用氟啶脲、毒死蜱和灭多威3种常用类型杀虫剂的常规剂量对皂角豆象成虫、初孵幼虫和卵进行防治试验。【结果】3种杀虫剂都可以有效的杀死皂角豆象初孵幼虫,接触氟啶脲、毒死蜱和灭多威3种杀虫剂后皂角豆象幼虫72 h死亡率分别为96.59%、100.00%和100.00%,灭多威和毒死蜱对皂角豆象成虫致死效果72 h为100.00%,灭多威对皂角豆象卵的效果最为明显,致死率达94.38%,氟啶脲对皂角豆象卵和成虫无明显致死效果。【结论】灭多威对皂角豆象的致死效果最好。     

小菜蛾对定虫隆的抗性生化机制初探

以定虫隆汰选的抗性指数为23.78倍抗性种群(CH-R),并以上海田间种群(SH-R,对定虫隆的抗性指数为9.16倍)作为参比种群,研究小菜蛾Plutella xylostlla(L.)对定虫隆的抗性机制,结果表明：CH—R种群多功能氧化酶O-脱甲基活力比相对敏感种群(SZ-S)提高1倍,而SH-R种群多功能氧化酶O-脱甲基活力虽有所提高,但与SZ-S种群相比差异并不显著;CH-R和SH-R种群羧酸酯酶比活力均明显高于Sz-S种群,分别为SZ-S种群的4.61和2.18倍,且CH-R种群的Km仅为SZ-S种群的1/20;酸性磷酸酯酶和碱性磷酸酯酶比活力种群间无明显差异;CH-R种群的几丁质酶活力降低48%,酚氧化酶活力降低60%。说明小菜蛾对定虫隆的抗性机制具有多因子性,多功能氧化酶解毒代谢能力的提高可能是主导抗性机制之一,羧酸酯酶、几丁质酶和酚氧化酶也参与了小菜蛾对定虫隆的抗性。     

棉铃虫几丁质合成酶1基因的时空表达分析及氟啶脲对其表达的影响

本研究旨在明确棉铃虫Helicoverpa armigera(Hübner)几丁质合成酶1(HaCHS1)基因在不同发育时期和不同组织的表达及氟啶脲处理后对该基因表达的影响。利用RT-PCR和RACE技术克隆获得棉铃虫HaCHS1基因,HaCHS1基因全长为5247 bp,其中开放阅读框4698 bp,编码1565个氨基酸,5′非翻译区为168 bp,3′非翻译区为381 bp。预测蛋白的相对分子质量为180.7 kDa,等电点为6.50,HaCHS1具有16个跨膜螺旋和6个N-糖基化位点。RT-qPCR检测结果表明,HaCHS1基因在预蛹期表达量最低,在蛹期第1天表达量最高。HaCHS1基因在头部的表达量最高,其次是表皮,而在中肠、气管、马氏管和脂肪体中的表达量均极低。亚致死浓度(60 mg/L)氟啶脲处理后,棉铃虫HaCHS1基因呈现出“抑制-激活-再抑制”的波动。本研究将为棉铃虫HaCHS1基因功能的研究奠定基础,为基于几丁质合成途径设计新药提供科学的理论依据。     

小菜蛾对定虫隆抗性种群的选育及交互抗性研究

用昆虫生长调节剂(insect growth regulator,简称IGR)定虫隆(chlorfluazuron)对源自深圳田间的小菜蛾(SZ-S)Plutella xylostella(L.)在室内进行抗性种群选育,经过8代饲养和6次药剂汰选,获得抗性种群(CH-R),与相对敏感种群Sz—S比较,抗性指数(R1)为23.78倍。CH-R种群在去除选择压力条件下饲养5代,抗性逐渐下降。抗性汰选前后分别测定了10种药剂的剂量—死亡毒力回归线,发现CH—R抗性种群对三氟氯氰菊酯、氯氰菊酯、辛硫磷、喹硫磷、灭多威、磺胺脲类衍生物—杀螨隆、微生物杀虫剂Bt和齐墩螨素无明显交互抗性,抗性倍数为0.4-1.7;对两种沙蚕毒素类杀虫剂杀螟丹和杀虫丹的敏感性却有所上升,有负交互抗性趋势。活体增效剂试验表明,增效醚(PBO)和三苯基磷酸酯(TPP)对定虫隆均有一定的增效活性,PBO的增效比最高为29倍,能够完全抑制对定虫隆的抗性,说明多功能氧化酶可能是主导抗性机制之一。     

Treatment of adult Coleoptera with a chitin synthesis inhibitor affects mortality and development time of their progeny

A group of insect growth regulators, the chitin synthesis inhibitors (CSIs), are being more widely used as many insects have become resistant to broad-spectrum insecticides. This study investigated the mode of action of one CSI, particularly looking at the delayed effect of treating adult insects on the survival and development of their progeny. The study describes the responses of adult stored grain beetles Sitophilus oryzae (L.) (Curculionidae) and Rhyzopertha dominica (F.) (Bostrichidae) to wheat treated with chlorfluazuron. For both species, wheat treated with chlorfluazuron reduced progeny survival at a constant rate from 1 day to 8 weeks after it had been treated. There was a direct, negative concentration-time relationship between the treatment of the adults with chlorfluazuron-treated wheat and the survival and developmental rate of their progeny. Adults that were pre-exposed for one or more weeks before oviposition to wheat treated with chlorfluazuron had significantly lower progeny survival than adults that were not pre-exposed. The EC₉₅ values were 16-fold higher for R. dominica and 40-fold higher for S. oryzae from assays without pre-exposure, than with pre-exposure. Pre-exposure of R. dominica with 0.1 mg kg^-1 and of S. oryzae with 0.4 mg kg^-1 of chlorfluazuron reduced progeny survival by 95%. Higher concentrations of chlorfluazuron produced a reduction in mean population developmental time of several days. These findings have important implications for bioassays of CSIs, since pre-exposure of the adults can significantly reduce the numbers of F1 progeny. Therefore standard bioassays may seriously underestimate the efficacy of the CSI being assayed.     

定虫隆对锈赤扁谷盗生长发育影响及其作用机理初探

定虫隆是一种昆虫生长调节抑制剂,研究其对锈赤扁谷盗的控制作用,将为锈赤扁谷盗的综合防治提供理论基础。本研究以锈赤扁谷盗幼虫为研究对象,用定虫隆拌粮进行饲喂,观察定虫隆对锈赤扁谷盗的亚致死效应,并利用实时荧光定量PCR(qPCR)技术,测定经定虫隆处理后锈赤扁谷盗幼虫几丁质合成酶1(CfCHS1)和几丁质合成酶2(CfCHS2)基因表达量的变化。结果表明:定虫隆对锈赤扁谷盗的毒力回归方程为y=7.514+1.81x(r=0.974),LD 10、LD 20、LD 30分别为0.008 mg/kg、0.014 mg/kg、0.021 mg/kg,亚致死剂量定虫隆可使锈赤扁谷盗幼虫发育历期明显延长(P<0.05),体重和几丁质含量明显降低(P<0.05),这说明了定虫隆对锈赤扁谷盗的生长发育有明显的抑制作用,可以有效控制锈赤扁谷盗的为害。qPCR结果显示,与对照组相比,LD 30处理后的锈赤扁谷盗幼虫的CfCHS 1基因表达量提高了74.7%,CfCHS 2基因的表达量提高了27.4%,均差异显著(P<0.05)。CfCHS 1和CfCHS2基因表达量的上调,可能是几丁质合成酶受到了抑制,锈赤扁谷盗为了维持机体的稳定,提高几丁质合成酶基因的表达量,从而形成一种代偿性增加的反馈机制,由此推测定虫隆可能作用于几丁质合成酶。     

不同小菜蛾田间种群对氟啶脲的抗性动态

【目的】了解不同种植模式的小菜蛾Plutella xylostella(L.)田间种群对氟啶脲(Chlorfluazuron)的抗性动态,旨在为该药剂的田间抗性管理提供参考。【方法】参照中华人民共和国农业行业标准"十字花科蔬菜小菜蛾抗性监测技术规程"(NY/T 2360-2013)进行。【结果】与敏感种群相比,不同监测点小菜蛾种群由于地理位置、种植模式、用药习惯等的不同,对氟啶脲的抗性表现出地区差异和年度间差异。小户型连年种植模式的广东广州地区小菜蛾田间种群对该药剂抗性相对最高,以中等及以上抗性水平为主,最高抗性比(RR值)为437.58;而规模化连年种植模式的广东惠州地区小菜蛾种群对该药剂的抗性仅次于广东广州地区,也以中等及以上抗性水平为主,最高RR值为337.18;小户型连年种植为主的连州地区小菜蛾种群对氟啶脲的抗性动态与广东惠州地区的非常相似,抗性水平比广东广州地区和广东惠州地区稍轻;山区小户型多样化种植模式的广西柳州地区小菜蛾田间种群对该药剂的抗性相对最低,以低水平抗性为主,最高RR值仅为23.24。但4个抗性监测点也存在抗性发展大趋势基本一致的共同点。具体表现在4个监测点小菜蛾种群对该药剂的抗性在2008年均为中等以上抗性水平,随后通过调整了用药策略,多数地区2009—2011年抗性下降至低水平(RR值小于10)。2012年随着田间防治压力的上升,氟啶脲用药量和用药频次再次增加,造成多数地区抗性再次上升至中等及以上水平,并持续到2014年。【结论】小菜蛾对氟啶脲的抗性田间稳定性不高,停用或过度依赖该药剂一段时间,抗性即出现下降或上升,基本与用药情况、频次和强度等呈正相关。     

溴虫腈、茚虫威与氟啶脲混配对小菜蛾毒力最佳配比筛选及田间防效研究

为了延缓小菜蛾Plutella xylostella(L.)抗药性的产生和发展,本研究选用常用的3种化学杀虫剂,即氟啶脲、溴虫腈、茚虫威,采用交互测定法进行了最佳配比的筛选,并根据孙云沛法计算其共毒系数,最后筛选出具增效作用的混配配方,氟啶脲∶溴虫腈(有效成分含量为13.20∶1.72),共毒系数为241;氟啶脲∶茚虫威(有效成分含量为2.20∶3.60),共毒系数为142。田间试验结果表明氟啶脲与溴虫腈混配2000倍液药后7d校正防效为84.24%,与其他处理的校正防效具有极显著差异;氟啶脲与茚虫威混配1000倍液药后7d校正防效为85.08%,与其他处理的校正防效有显著性差异。     

Interaction of treatment of both adult and immature Coleoptera with a chitin synthesis inhibitor affects mortality and development time of their progeny

Chitin synthesis inhibitors, like many other insect growth regulating insecticides, do not kill adult insects but cause mortality of the immature stages. Pre-exposure of adult stored grain Coleoptera, Rhyzopertha dominica (F.) (Bostrichidae) and Sitophilus oryzae (L.) (Curculionidae) and development of their progeny in grain treated with the chitin synthesis inhibitor, chlorfluazuron, influenced the mortality and development rate of the progeny. Hatch rate of eggs from R. dominica adults that had both developed and laid on wheat treated with 0.75 mg kg–1 chlorfluazuron was reduced by almost 50% compared with untreated eggs, with an LC50 of 0.84 mg kg–1 . Eggs laid on treated wheat by R. dominica adults that had been exposed only to treated wheat for 2 weeks before oviposition showed greater reduction in hatch: 75% reduction of normal hatch rate at 0.25 mg kg–1 and almost 100% reduction at 2 mg kg–1 chlorfluazuron, with an LC50 of 0.19 mg kg–1 chlorfluazuron. X-rays were used to monitor the development and mortality of the immature stages of S. oryzae that developed within the wheat grains. Numbers of eggs laid were not affected by chlorfluazuron treatment. The combination of pre-exposure of adults and chlorfluazuron concentration had an additive effect on mortality of immature S. oryzae. Pre-exposure of adults caused most mortality in the first three weeks of development (eggs and larvae), whereas development in treated wheat caused mortality from weeks 3 to 8 (pupae and adults); higher concentrations of chlorfluazuron caused higher mortality. Development in wheat treated with 1 mg kg–1 chlorfluazuron caused 12% corrected overall mortality of progeny while pre-exposure to the same concentration and development in untreated wheat caused 29% corrected mortality. Pre-exposure combined with development in wheat treated with 1 mg kg–1 caused 30% corrected mortality. Thus, pre-exposure of adults appears to have a greater effect on mortality of S. oryzae progeny than development of immature stages in treated grain. Development on treated grain had no effect on development rate. Pre-exposure of adults did not appear to affect the rate of immature development, as assessed by X-rays, but did slow the emergence of adults, lengthening development time by about 2 days. This significant, additive effect of pre-exposure of adults on the mortality of their progeny will enhance the toxicity of chitin synthesis inhibitors such as chlorfluazuron, since most adults receive treatment when the immature stages are treated in crops either before they are harvested or in storage. Assessing the proportion of eggs that hatch from pre-exposed adults would be a simpler bioassay for CSIs.