小菜蛾对Bt的抗性及其治理

本文综合论述小菜蛾对Ｂｔ的抗性现状,发展特点与作用机制,并提出相应的抗性治理对策 。     

Inheritance of resistance to a Bacillus thuringiensis toxin in a field population of diamondback moth (Plutella xylostella)

Inheritance of resistance to the Bacillus thuringiensis Berl. CryIA(b) crystal protein was studied in Plutella xylostella L. (diamondback moth). A field population 50-fold more resistant to CryIA(b) than a control susceptible strain was used. Dose-mortality curves of the resistant population, the susceptible strain and the F₁ from the two reciprocal crosses were compared. Resistance transmission to the F₁ was dependent on the sex of the resistant progenitor. Sex ratio of the survivors to high doses of CryIA(b) in the F₁ of the two reciprocal crosses did not corroborate the preliminary hypothesis of resistance being due to a recessive sex-linked allele. Since, in a previous work, the loss of CryIA(b) binding capacity of resistant insects had been demonstrated, binding to midgut tissue sections from F₁ individuals was also analysed. The presence of binding in all of the F₁ preparations showed that, at least, a recessive autosomal allele was responsible for the loss of binding capacity in the resistant population.     

云南通海小菜蛾种群抗药性监测及田间药效评价

为掌握云南蔬菜主产区通海县小菜蛾种群对常用杀虫剂的敏感性及其田间防治效果, 采用浸叶法和田间小区试验对常用杀虫剂进行室内毒力测定和田间药效试验。结果表明：通海县小菜蛾种群对丁醚脲和Bt的敏感性最高, 仍处于敏感水平, 对茚虫威属低抗水平, 对虫螨腈和多杀菌素的抗性倍数分别为24.28和31.68倍, 属中抗水平, 对氯虫苯甲酰胺抗性倍数为44.62倍, 到高抗水平, 对阿维菌素的敏感性最差, 抗性倍数829.90倍, 达极高抗水平。抗性水平和田间药效呈一定相关性, 氯虫苯甲酰胺和阿维菌素药后7 d对小菜蛾的防治效果均低于50%, 茚虫威、多杀菌素和丁醚脲的田间防效较好。通海县小菜蛾可选择的防治药剂包括茚虫威、多杀菌素和丁醚脲, 注意不同药剂之间的轮换和交替使用。     

3种生物源杀虫剂对杜仲梦尼夜蛾的毒力及防效

针对专性为害杜仲的食叶害虫杜仲梦尼夜蛾(Orthosia songi Chen et Zhang)幼虫进行室内毒力测定,比较了3种生物源杀虫剂对其3龄和5龄幼虫的杀虫活性,并进行了林间药效测定和防治示范试验。结果显示:甲氨基阿维菌素苯甲酸盐(甲维盐)对3龄和5龄幼虫的LC50值分别为0.152 5和0.204 7μg/L,苦参碱的LC50值分别为65.306 0和124.735 8μg/L,印楝素的LC50值分别为165.871 7和257.749 0μg/L。林间药效测定结果显示5.7%甲维盐微乳剂300万倍液防治效果最好,7d后校正死亡率达91.34%。防治示范试验表明,5.7%甲维盐微乳剂75 000倍液防治效果达95.69%,显著高于0.3%苦参碱水剂750倍液的防治效果(80.28%),且药剂成本7.5元/hm2,仅为后者的1.9%。     

Evidence for Resistance to Bacillus thuringiensis (Bt) subsp. kurstaki HD-1, Bt subsp. aizawai and Abamectin in Field Populations of Plutella xylostella from Malaysia

The efficacy of Bacillus thuringiensis (Bt) subsp. kurstaki HD-1 (‘Dipel’™; Btk; CryIA & CryII) and Bt. subsp. aizawai (‘Florbac’™; Bta; CryIA & CryIC) was assessed against larvae from various field populations of Plutella xylostella (F2 generation) collected in the Cameron Highlands, Malaysia in April 1994 and a lowland population (SERD 2; F10 generation) collected in December 1993. Evidence of resistance to Btk and to a lesser extent Bta is reported in these populations (LC₅₀ Toxicity Ratios [TR]=3–14 and 2–8 respectively), most notably in SERD 2. The first recorded evidence of resistance to abamectin (TR=17–195-fold) in field populations of P. xylostella is also reported. In an unselected sub-population of SERD 2, the TR values for Btk, Bta and abamectin declined 2- to 3-fold (P<0·01) over six generations in the laboratory (F10–F16) while in sub-populations of SERD 2 selected with these products (F11–F15) there was a significant (P<0·01) increase in the TR (15-, 3- and 2·5-fold respectively) when compared with the F10 generation. This suggests the presence of marked resistance to Btk and some resistance to Bta and abamectin. There is also evidence of slight cross-resistance to Btk in the Bta-selected sub-population but no evidence for the reverse selection of resistance or for cross-resistance between Btk and abamectin. Concurrent selection studies (F11–F15) with another sub-population of SERD 2 demonstrated resistance to the acylurea insect growth regulator, teflubenzuron (‘Nomolt’™) (29-fold increase in TR). Based on the selection experiments with SERD 2, estimates of realised heritability (h²) of resistance gave very high values for teflubenzuron and Btk (c.0·7) and moderate values for abamectin and Bta (c.0·3). The results are discussed in relation to integrated pest management (IPM) and insecticide resistance management (IRM) strategies for P. xylostella.     

取食不同寄主的小菜蛾对呋喃威和巴丹敏感性变化

取食不同寄主植物的小菜蛾３龄幼虫对呋喃威和巴丹的敏感性发生了变化。其中取食萝卜的小菜蛾最为敏感,其次为甘蓝、菜心、白菜和西洋菜,取食花椰菜的最不敏感。但用不同寄主植物饲养小菜蛾１个世代后,统一用菜心饲养至３龄,再分别用上述药剂测定,其结果敏感性差异不明显。     

4种增效剂对3种小菜蛾防治药剂的增效作用

为明确增效剂对防治小菜蛾的杀虫剂的增效作用,减少化学农药用量,分别采用浸叶法和茎叶喷雾法进行了室内毒力测定和田间药效试验.室内测定结果表明,3种供试杀虫剂中,虫螨腈和乙基多杀菌素对小菜蛾毒力较强,其LC50分别为6.303 mg/L和10.479 mg/L;3种杀虫剂分别与不同增效剂混配后均具有一定的增效作用,增效比介...     

小菜蛾幼虫对拟除虫菊酯类杀虫剂的抗药性与多功能氧化酶的关系

作者就上海梅陇、广州天河和江西莲塘的小菜蛾对拟除虫菊酯的抗药性及其与微粒体多功能氧化酶(MFO)的关系进行了研究。结果表明,上海种群(R)对溴氰菊酯、氰戊菊酯和氯菊酯的 LD_(50)分别是江西种群(S)的>10414倍、2102倍和245倍。广州种群分别为>10414倍、>3569倍和1533倍。活体增效试验表明,酯酶抑制剂 TBPT 在低剂量(0.208μg/虫)时,对溴氰菊酯和氯菊酯都无增效作用,在高剂量(2.08μg/虫)时分别增效41.7倍和110倍。用 MFO的抑制剂 PB 作同样处理时,低剂量的 PB 对溴氰菊酯和氯菊酯的增效作用分别为5倍和12.9倍;高剂量的 PB 对溴氰菊酯增效562倍以上。~(14)C-氰戊菊酯代谢的离体研究结果表明,R 小菜蛾代谢~(14)C-氰戊菊酯的速度是 S 小菜蛾的2.1倍,TBPT 抑制~(14)C-杀灭菊酯的代谢约20%,而PB 抑制50%以上。由此可以得出结论,MFO 是小菜蛾对拟除虫菊酯的主要机理之一。     

广州、深圳地区小菜蛾对定虫隆、Bt的抗性监测

采用 Potter's 喷雾塔喷雾的方法测定广州和深圳菜区小菜蛾对儿丁质合成抑制剂定虫隆、氟虫脲、伏虫隆、氟铃脲的抗药性。结果表明,深圳菜区小菜蛾对定虫隆产生明显抗性,1990年11月测定抗性倍数为15.0,1991年12月为70.9,对氟虫脲、伏虫隆、氟铃脲具有不同程度交互抗性,抗性倍数分别为26.7,15.5 和5.8。广州菜区小菜蛾对以上药剂均未产生抗性(抗性倍数最高为2.8)。采用浸渍法测定小菜蛾对苏云金杆菌 Bt 抗性的结果表明,深圳菜区小菜蛾对 Bt 的抗性逐年提高,1990年12月测定的抗性倍数为21.1,1991年12月为26.9,1992年3月为35.0,广州菜区小菜蛾具有强的耐药性或低抗药性,抗性倍数8—9。     

常用杀虫剂对菜蛾绒茧蜂的影响及毒理机制研究

田间采集试虫室内测定结果表明,敌敌畏、灭多威和杀虫双对菜蛾绒茧蜂Apanteles plutellae高毒,乙酰甲胺磷对绒茧蜂毒性较低,而氰戊菊酯、氯氰菊酯、氟虫腈、阿维菌素、定虫隆和Bt则是低毒的。菜蛾绒茧蜂AChE的Km及Vmax值分别是小菜蛾的0.22和2.08倍,AChE对敌敌畏的敏感性(K/em>i值)分别是小菜蛾的10.37倍。100 mg/L的胡椒基丁醚(PB)或磷酸三苯酯(TPP)均可使氰戊菊酯明显增效,其中PB的增效作用显著高于TPP。体内抑制实验结果表明,PB和TPP对绒茧蜂AChE活力无显著影响,低浓度(100 mg/L)的PB即可显著抑制绒茧蜂的α-NA和β-NA CarE活力,且抑制率高于TPP,TPP仅在高浓度(1 000 mg/L)时对绒茧蜂的两种CarE活力有显著抑制作用。由此推断,与小菜蛾相比,菜蛾绒茧蜂对有机磷的高敏感性与其显著较高的AChE敏感性有关;此外,多功能氧化酶的解毒代谢在菜蛾绒茧蜂对氰戊菊酯的耐药性中具重要作用。     

京郊西兰花小菜蛾的田间防治药剂筛选与评价

为评价高效氯氰菊酯、溴氰虫酰胺、苏云金杆菌、甲氨基阿维菌素苯甲酸盐、乙基多杀菌素等5种杀虫剂对小菜蛾的田间药效,本文采用喷雾法进行了田间试验。结果表明,10%溴氰虫酰胺可分散油悬浮剂、6%乙基多杀菌素悬浮剂对小菜蛾在药后1~7 d的防效较好;32000 IU/mg苏云金杆菌可湿性粉剂、32000 IU/mg苏云金杆菌可湿性粉剂与10%溴氰虫酰胺可分散油悬浮剂分别按50%推荐用量组成的1∶1的混配剂,药后1 d的防效仅在60%左右,速效性较差,但是药后3~7 d的防效较好。其中,混配剂药后3 d的防效高达90.70%。5%甲氨基阿维菌素苯甲酸盐水分散粒剂和4.5%高效氯氰菊酯乳油在药后1~7 d的防效均较差。因此,在西兰花生产上可使用减量的溴氰虫酰胺与苏云金杆菌混配剂进行小菜蛾的防治,以达到农药减量增效防治小菜蛾的目的;在小菜蛾暴发时,可使用溴氰虫酰胺或乙基多杀菌素,以达到迅速防治的目的。