Determination of Resistance to Seven Insecticides in Plutella xylostella L. in Fields of Northern Hunan

The resistance of field populations of Plutella xylostella, from the three vegetable producing areas （Nianyuxu Town of Yueyang City, Canggang Town of Changde City and Shatou Town of Yiyang City） in northern Hunan, to seven insecticides was determined using leaf dipping method in door. The results showed that Plutella xylostella showed an extremely high-level resistance to beta-cypermethrin （resistance ratio, RR=257.13）, a high-level resistance to abamectin （RR=135.15） and indoxacarb （RR=103.08） and a moderate-level resistance to chlorfenapyr and emamectin benzoate. But Plutella xylostella is relatively sensitive to chlorantraniliprole and Bacillus thuringiensis （Bt）. Therefore, the prevention of Plutella xylostella in northern Hunan should focus on the alternative use of chlorfenapyr, emamectin benzoate, chlorantraniliprole and Bacillus thuringiensis and avoid the use of beta-cypermethrin so as to delay the generation and development of resistance to insecticides in Plutella xylostella.

Biochemical Mechanism of Chlorantraniliprole Resistance in the Diamondback Moth, Plutella xylostella Linnaeus

The insecticide chlorantraniliprole exhibits good efifcacy and plays an important role in controlling the diamondback moth, Plutella xylostella Linnaeus. However, resistance to chlorantraniliprole has been observed recently in some ifeld populations. At present study, diamondback moths with resistance to chlorantraniliprole （resistant ratio （RR） was 82.18） for biochemical assays were selected. The assays were performed to determine potential resistance mechanisms. The results showed that the selected resistant moths （GDLZ-R） and susceptible moth could be synergized by known metabolic inhibitors such as piperonyl butoxide （PBO）, triphenyl phosphate （TPP） and diethyl-maleate （DEM） at different levels （1.68-5.50-fold and 2.20-2.89-fold, respectively）, and DEM showed the maximum synergism in both strains. In enzymes assays, a high level of glutathione-S-transferase （GST） was observed in the resistant moth, in contrast, moths that are susceptible to the insecticide had only 1/3 the GST activity of the resistant moths. The analysis of short-term exposure of chlorantraniliprole on biochemical response in the resistant strain also showed that GST activity was signiifcantly elevated after exposure to a sub-lethal concentration of chlorantraniliprole （about 1/3 LC50, 12 mg L-1） 12 and 24 h, respectively. The results show that there is a strong correlation between the enzyme activity and resistance, and GST is likely the main detoxiifcation mechanism responsible for resistance to chlorantraniliprole in P. xylostella L., cytochrome P450 monooxygenase （P450） and carboxy-lesterase （CarE） are involved in to some extent.

Characterization of carboxylesterase PxαE8 and its role in multi-insecticide resistance in Plutella xylostella(L.)

Carboxylesterase(CarE)was considered as important phase-I detoxifying enzymes which participated in detoxification of different types of insecticides.Up-regulation of CarE genes has been proved playing a major role in insecticide resistance in many pest insects,but its involvement in resistance to insecticides in Plutella xylostella has been rarely reported.In this study,a CarE cDNA named PxαE8 was identified in P.xylostella,which has an open reading frame of 1599 nucleotides and putatively encodes 532 amino acids.The investigation of spatial expression profiles of PxαE8 revealed that it was expressed in all developmental stages,especially in larvae and adults.The body part/tissue-specific expression profiles showed that the PxαE8 mainly expressed in fat body,malpighian tubule and hemolymph of larvae.Further,the relative expression of PxαE8 in two multi-resistant field populations,Hainan(HN)and Guangdong(GD)populations,was found 24.4-and 15.5-fold higher than that in susceptible population,respectively.Knockdown of PxαE8 by RNA interference dramatically increased the mortalities of larvae of HN population treated with LC_(50) of beta-cypermethrin and phoxim by 25.3 and 18.3%,respectively.These results suggested that up-regulation of PxαE8 was involved in resistance to both beta-cypermethrin and phoxim in P.xylostella,which shed light on further understanding of molecular mechanisms of multi-insecticide-resistance in P.xylostella and other pest insects.

CRISPR/Cas9-based functional characterization of Px ABCB1 reveals its roles in the resistance of Plutella xylostella(L.)to Cry1Ac,abamectin and emamectin benzoate

The identification of functional midgut receptors for pesticidal proteins produced by Bacillus thuringiensis(Bt)is critical for deciphering the molecular mechanism of Bt resistance in insects.Reduced expression of the PxABCB1 gene was previously found to be associated with Cry1Ac resistance in the diamondback moth,Plutella xylostella(L.).To directly validate the potential receptor role of PxABCB1 and its contribution to Bt Cry1Ac toxicity in P.xylostella,we used CRISPR/Cas9 to generate a homozygous knockout ABCB1KO strain with a 5-bp deletion in exon 3 of its gene.The ABCB1KO strain exhibited a 63-fold resistance to Cry1Ac toxin compared to the parental DBM1Ac-S strain.Intriguingly,the ABCB1KO strain also exhibited significant increases in susceptibility to abamectin and emamectin benzoate.No changes in susceptibility to various other Bt Cry proteins or synthetic insecticides were observed.The knockout strain exhibited no significant fitness costs.Overall,our study indicates that PxABCB1 can protect the insect against avermectin insecticides on one hand,while on the other hand it facilitates the toxic effect of the Bt Cry1Ac toxin.The results of this study will help to inform integrated pest management approaches against this destructive pest.

小菜蛾(Plutella xylostella L.)抗药性的研究现状

小菜蛾是十字花科蔬菜上最主要的害虫 ,也是目前产生抗药性最严重的害虫之一。本文就国内外小菜蛾在抗药性发展、抗性消长规律、抗性机理、抗性遗传。

cDNA cloning and characterization of t he carboxylesterase pxCCE016b from the diamondback moth, Plutella xylostella L.

Carboxylesterase is a multifunctional superfamily and can be found in almost all living organisms. As the metabolic enzymes, carboxylesterases are involved in insecticides resistance in insects for long time. In our previous studies, the enhanced c arboxylesterase activities were found in the chlorantraniliprole resistance strain of diamondback moth（DBM）. However, t he related enzyme gene of chlorantraniliprole resistance has not been clear in this strain. Here, a full-length c DNA of carboxylesterase pxCCE016 b was cloned and exogenously expressed in Escherichia coli at the first time, which contained a 1 693 bp open reading frame（ORF） and encoded a protein of 542 amino acids. Sequence analysis showed that this c DNA has a predicted mass of 61.56 k Da and a theoretical isoelectric point value of 5.78. The sequence of deduced amino acid possessed the classical structural features： a type-B carboxylesterase signature 2（EDCLYLNVYTK）, a type-B carboxylesterase serine active site（FGGDPENITIFGESAG） and the catalytic triad（S er186, Glu316, and His444）. The real-time quantitative PCR（q PCR） analysis showed that t he expression level of the p x CCE016 b was significantly higher in the chlorantraniliprole resistant strain than in the susceptible strain. Furthermore, pxCCE016 b was highly expressed in the midgut and epidermis of the DBM larvae. When the 3rd-instar larvae of resistant DBM were exposed to abamectin, alpha-cypermethrin, chlorantraniliprole, spinosad, c hlorfenapyr and indoxacarb insecticides, the up-regulated expression of pxCCE016 b was observed only in the group treated by chlorantraniliprole. In addition, recombinant vector p ET-pxCCE016 b was constructed with the most coding region（1 293 bp） and large number of soluble recombinant proteins（less than 48 k Da） were expressed successfully with prokaryotic cell. Western blot analysis showed that it was coded by pxCCE016 b. All the above findings provide important information for further f unctional study, although we are uncertainty whether the pxCCE016 b gene is actually i nvolved in chlorantraniliprole resistance.

小菜蛾RyR调控蛋白FKBP基因克隆及其时空表达谱

【目的】明确FK506结合蛋白(FKBP)基因在小菜蛾对氯虫苯甲酰胺抗性形成中的作用,筛选出起主要作用的关键FKBP基因,为阐明小菜蛾抗双酰胺类杀虫剂的分子机理提供新思路。【方法】以抗氯虫苯甲酰胺种群和敏感种群小菜蛾为研究对象,采用浸叶法测定不同种群小菜蛾对氯虫苯甲酰胺的敏感性差异;利用cDNA末端快速扩增(RACE)方法克隆3个FKBP基因(FKBP8、FKBP12和FKBP52)的全长序列,并通过GSDS 2.0、CDD和MEME在线分析软件分析其基因结构与蛋白保守结构域和Motif;采用实时荧光定量PCR分析抗性种群不同发育阶段和敏感、抗性种群4龄幼虫不同组织FKBP基因的时空表达特性。【结果】生物测定结果显示,抗性种群小菜蛾对氯虫苯甲酰胺的抗性倍数为122.67倍,属于高水平抗性。实时荧光定量PCR分析发现,抗性种群小菜蛾体内3个FKBP基因的相对表达量均显著高于敏感种群(P<0.05,下同),其中FKBP8基因的表达差异最显著,是敏感种群的968倍。通过RACE方法克隆得到FKBP52、FKBP8和FKBP12基因的全长序列,长度分别为1473、1525和649 bp,分别编码423、307和108个氨基酸残基,其蛋白均为亲水蛋白。FKBP52、FKBP8和FKBP12基因具有相同的基因结构,FKBP52和FKBP12蛋白具有相同的保守结构域FkpA,而FKBP8蛋白具有2个不同的保守结构域。抗性种群小菜蛾4龄幼虫体内3个FKBP基因表达量均高于蛹期,其中FKBP12和FKBP8基因在4龄幼虫中的表达量最高,显著高于其他龄期和蛹期。FKBP8基因在抗性种群小菜蛾中肠和表皮中的表达量显著高于敏感种群,分别是敏感种群的3.2和3.7倍。【结论】FKBP52、FKBP8和FKBP12基因在氯虫苯甲酰胺抗性种群小菜蛾中均过量表达,其中FKBP8基因在高抗氯虫苯甲酰胺种群小菜蛾的中肠高表达,表明其可能通过过量表达参与小菜蛾对氯虫苯甲酰胺的抗药性。

Tebufenozide resistance is associated with sex-linked inheritance in Plutella xylostella

The diamondback moth （DBM）, Plutella xylostella （L.）, is a major pest of cruciferous crops. Tebufenozide, a novel nonsteroidal ecdysone agonist, exhibits good efficacy and has played an increasingly important role in the control of Lepidopteran pests in China. For its resistance management, the genetic basis of tebufenozide resistance was studied using a laboratory selected resistant strain of DBM （resistant ratio, RR = 268）. A series of crosses with laboratory susceptible and resistant strains revealed that tebufenozide resistance in this pest was partially biased toward female heredity, with a large difference in RR for F1 （RR = 29） and rF1 progeny （RR = 147）. The dominance calculated for these 2 cross progeny was -0.788 and 0.09, respectively. Further analysis showed that the susceptible male and female larvae were similar in theft sensitivity to tebufenozide, but the resistant female larvae showed significantly higher resistance than the resistant male larvae. The heredity of tebufenozide resistance in DBM might be linked with the W sex chromosome, which suggested that DBM has the ability to develop high levels of resistance to tebufenozide. This is the first report of sex-linked inheritance oftebufenozide resistance in P xylostella （L.）.

Influence of seasonal migration on evolution of insecticide resistance in Plutella xylostella

The diamondback moth,Plutella xylostella(L.),is one of the most destructive migratory pest species of cruciferous vegetables worldwide and has developed resistance to most of the insecticides used for its control.The migration regularity,migratory behavior,and relationship between flight and reproduction of P.xylostella have been widely reported.However,the effect of migration on insecticide resistance in this pest is still unclear.In this study,the effect of migration on P.xylostella resistance to seven insecticides was investigated using populations across the Bohai Sea that were collected in the early and late seasons during 2017–2019.The bioassay results showed that the early season populations of P.xylostella from south China possessed much higher resistance to insecticides because of intensive insecticide application;alternatively,the late season populations migrated from northeast China,where the insecticides were only used occasionally,showed much lower insecticide resistance.The genome re-sequencing results revealed that,among the eight mutations involved in insecticide resistance,the frequencies of two acetylcholinesterase mutations(A298S and G324A)responsible for organophosphorus insecticide resistance were significantly decreased in the late season populations.The results indicated that P.xylostella migration between tropical and temperate regions significantly delayed the development of insecticide resistance.These findings illustrated the effect of regional migration on the evolution of insecticide resistance in P.xylostella,and provided foundational information for further research on the relationship between migration and insecticide resistance development in other insects.

Seasonal changes of resistance to fenvalerate and cypermethrin in the larval parasitoid Cotesia plutellae （Hymenoptera： Braconidae）

The seasonal changes of insecticide resistance and stability in hymenopteran Cotesia plutellae, collected from Jianxin, Fuzhou-City, and Shangjie, Minhou-County, Fujian, China, were assessed by using a dry residual film method. The resistance to two insecticides in the field populations of C. plutellae was not stable under insecticide-free conditions in the insectarium. Compared with susceptible F11 progeny of C. plutellae in the insectarium, the resistance ratios （RR） in F0 parents were 18.4 for fenvalerate and 11.4 for cypermethrin based on LC50 at 9 hours, and 32.8 for fenvalerate and 28.5 for cypermethrin based on LC50 at 24 hours when the parasitoids were left in contact with the insecticides for 1 hour and mortalities were recorded at 9 and 24 hours, respectively. However, the RR in a field population of C. plutellae were 9.2 for fenvalerate and 12.7 for cypermethrin, if the parasitoids were left in contact with the insecticides for 24 hours. The resistances to the two pyrethroids in other field populations collected from Jianxin and Shangjie from November 2000 and July 2004 were also determined. Significant seasonal variations of resistance to the two insecticides in the field populations of C. plutellae were found. The RR were 3.0-18.4 for fenvalerate and 4.8-20.6 for cypermethrin in Jianxin populations from November 2000 to April 2002 based on LC50 at 9 h, and 2.3-13.6 for fenvalerate and 3.6-16.0 for cypermethrin in Shangjie populations from May 2002 to July 2004 based on LC50 at 24 hours. The resistance levels were high in spring and autumn and decreased sharply in summer. In addition, significant recovery from the knocked-down caused by the insecticides was found in the F0 and field populations of C. plutellae which were resistant to fenvalerate and cypermethrin if the parasitoids were left in contact with the pyrethroids for 1 hour. However, no recovery was found in susceptible F11 progeny.

敏感和抗阿维菌素小菜蛾的生物适合度

阿维菌素汰选的小菜蛾抗性种群 (ABM- R)与相对敏感种群 (ABM- S)相比不表现繁殖不利性。 ABM- R种群的交配率、有效产卵指数和孵化率均显著大于 ABM- S种群 ,ABM- R种群的内禀增长率为 0 .139,是 ABM- S种群的 1.19倍 ,相对适合度为 ABM- S种群的1.4 9倍。建立了 ABM- S和 ABM- R种群的生命表 ,并对抗性治理进行了讨论。

华南小菜蛾田间种群对氯虫苯甲酰胺已产生严重抗性

2009—2011年在广东连州、惠州、佛山、广州和广西柳州、江西信丰等多个华南区主要菜场开展小菜蛾对氯虫苯甲酰胺的抗药性监测。结果发现,与室内敏感种群的敏感基线相比(LC50=0.13 mg/L),各监测点在2009年秋季均为敏感水平,2010年秋季部分地区出现敏感性下降和低水平抗性,而2011年春季除了监测到敏感性下降和低水平抗性外,还发现个别监测点产生中等水平抗性,抗性上升趋势明显。随后,在广州增城菜区监测到一例对氯虫苯甲酰胺产生极高水平抗性的小菜蛾田间种群,其当代和F1代虫源的LC50值分别为78.78、59.14 mg/L,抗性倍数分别为606.00和454.92,达极高抗性水平。分析小菜蛾对氯虫苯甲酰胺产生抗药性的关键因素,认为过度依赖该药、随意提高施用剂量、不合理混配、连年连片单一种植模式等可能是有利于抗药性发展的关键因素。

广东小菜蛾对阿维菌素的抗性研究

广东省供港菜场小菜蛾对阿维菌素的抗性有逐年上升趋势 ,1992年抗性为 2倍 ,1994年为 12倍 ,1996年达 2 0倍 .广州内陆菜区与供港菜场 1992和 1999年小菜蛾对几种蔬菜常用药剂的抗性对比表明 ,2个菜区小菜蛾对阿维菌素、Bt制剂及昆虫生长调节剂定虫隆的抗性均有较大幅度地提高 ,而供港菜场小菜蛾的抗性更强 ;对敌敌畏、灭多威、氰戊菊酯及杀螟丹等有机化学农药的抗性 ,1992与 1999年则差别不大 ,象氰戊菊酯这样近年较少使用的药剂 ,抗性有减弱的迹象 .抗Bt品系小菜蛾对阿维菌素无交互抗性 ,对阿维菌素敏感的小菜蛾在阿维菌素的选择压力下亦会产生抗性 ,连续选育 2 0代 ,抗性倍数达 11.5 5倍 .用阿维菌素选育的抗性品系对定虫隆产生了明显的抗性 。

解毒酶系在小菜蛾对阿维菌素抗性中的作用

对阿维菌素敏感 (ABM- S)和抗性 (ABM- R)种群小菜蛾的羧酸酯酶 (Car E)、谷胱甘肽 S-转移酶 (GST)和多功能氧化酶 (MFO) O-脱甲基活力进行了比较。结果显示 ,除 1～ 2龄外 ,ABM- R种群的 Car E活力显著高于 ABM- S种群 ,显著性随幼虫龄期的增长而增大 ,ABM- R种群 4龄末期幼虫的 Car E比活力为 ABM- S种群的 2 .2 5倍。动力学研究表明 ,可能是低龄幼虫中酶分子的变构起主要作用 ,而随着虫龄增长 ,酶分子数量的增加对抗性的作用逐渐增大。从酯酶同工酶等电聚焦电泳得出 ,ABM- R种群的 E7、E13和 E15同工酶活力显著提高是导致 ABM- R种群酯酶活力提高的主要原因。ABM- S和 ABM- R种群 GST的活力差异在1～ 2龄期最大 ,为 2 .0 9倍 ,随幼虫龄期的增大而降低 ,4龄幼虫期的 GST无种群差异。未检测到多功能氧化酶的

杀虫双和杀螟丹选育对小菜蛾抗药性的形成及其抗性机制

用杀虫双和杀螟丹在实验室以点滴法处理小菜蛾Plutella xylostella L.四龄幼虫,以连续继代药剂淘汰选育其抗药性。至35代,药剂汰选的小菜蛾对杀虫双和杀螟丹的抗药性较选育前正常品系分别提高了51倍和25倍。其抗药性的形成发展均呈S形,可认为已成为抗性品系。以有机磷、氨基甲酸酯、拟除虫菊酯及有机氮等11种杀虫剂测试抗杀虫双小菜蛾品系和抗杀螟丹小菜蛾品系对常用药剂的敏感度结果表明:对杀虫双、杀螟丹和杀虫环之间有较严重的正交互抗性;对敌敌畏、马拉硫磷和杀螟松有轻微交互抗性产生;对溴氰菊酯、氯氰菊酯、氯菊酯和灭多威、久效威等药剂更加敏感,呈负交互抗性。用聚丙烯酰胺凝胶电泳(PAGE)法测定表明,抗药性产生与特异性酯酶的形成有一定关系。用比色法和酸度法测定,抗性品系的乙酰胆碱酯酶(AchE)活性降低,羧酸酯酶(CarE)活性无差异。加增效剂Pb和SV_1于四龄幼虫表皮,对抗杀虫双小菜蛾品系分别有6.28及1.45倍的增效作用;对抗杀螟丹小菜蛾品系分别有4.85及1.39倍的增效作用,可见多功能氧化酶(MFO)为小菜蛾抗杀虫双和抗杀螟丹的重要因子。

广东小菜蛾对苏芸金杆菌的抗性研究

广东省深圳、东莞、惠阳及博罗等供香港（以下简称供港）菜区小菜蛾对有机化学农药的抗性与广州内销菜区相近或稍高，对Ｂｔ杀虫剂的抗性则是供港菜区明显高于广州内销菜区。几种酶抑制剂ＴＰＰ、ＳＶ１及Ｐｂ对Ｂｔ制剂无明显增效作用，可见小菜蛾对Ｂｔ制剂的抗性与酯酶和多功能氧化酶（ＭＦＯ）的关系不大。用Ｂｔ制剂Ｄｉｐｅｌ（大宝）连代选育小菜蛾敏感品系，选育１８代，小菜蛾的抗性较选育前提高３５倍。该抗性品系小菜蛾对个别菌株Ｂｔ及巴丹、杀虫双、速灭杀了、万灵、敌敌畏等无交互抗性，而对昆虫生长调节抑制剂有轻微交互抗性。相反，用巴丹和杀虫双选育出的小菜蛾抗性品系对Ｄｉｐｅｌ仍表现敏感。抗性品系小菜蛾在无触毒条件下饲养，抗性会自然减退，但不同类杀虫剂的抗性减退速率不尽相同。

不同地区小菜蛾对杀虫剂的抗性差异

室内用浸渍法测定了 14种杀虫剂对山东泰安和浙江杭州两地小菜蛾种群的毒力。结果表明 ,两地小菜蛾对溴氰菊酯产生了高水平抗性 ,分别达 6 3.9和 52 .5倍 ;对氟啶脲的抗性也分别达 35.0和 12 2 .1倍 ;常用的有机磷类、灭多威和杀虫双等药剂对它们的毒力均较低 ;两个小菜蛾种群对阿维菌素和氟虫腈最敏感。

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（ｉｎｓｅｃｔｇｒｏｗｔｈｒｅｇｕｌａｔｏｒ，简称ＩＧＲ）定虫隆（ｃｈｌｏｒｆｌｕａｚｕｒｏｎ）对源自深圳田间的小菜蛾（ＳＺＳ）Ｐｌｕｔｅｌａｘｙｌｏｓｔｅｌａ（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（ＲＩ）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。

表皮穿透和GABA_A受体不敏感性在小菜蛾对阿维菌素抗性中的作用

用氚标记阿维菌素点滴处理阿维菌素敏感 (ABM S)和抗性 (ABM R)种群小菜蛾幼虫 ,结果显示 ,在 5～ 36 0min内的 7个不同处理时间 ,ABM R种群的平均表皮穿透量比ABM S种群少 1 5倍 ,处理 2 4h后 ,ABM R种群仍有 45 9%的3 H 阿维菌素滞留于体表 ,而ABM S种群却有 98 4%的药剂穿透表皮。放射配体结合分析表明 ,GABAA 受体结合性质的改变是小菜蛾对阿维菌素的另一抗性机制 ,ABM S种群 (Kd=10 936 8± 0 4374nmol L)和ABM R种群 (Kd=9 832 8± 0 3933nmol L)的受体亲和力无显著差异 ,但抗性种群的最大结合量 (Bmax =71 2 842± 4 9910fmol mg蛋白 )比敏感种群 (Bmax =112 0 2 5 5± 7 8418fmol mg蛋白 )降低 6 3 6 % ,即抗性是受体数目的减少而非结构上的改变。

药剂对小菜蛾抗性及敏感品系乙酰胆碱酯酶抑制作用比较

采用浸叶法测定了云南通海、元谋和澜沧的小菜蛾plutella xylostella田间种群对常用杀虫剂的抗药性。结果表明,云南上述地区小菜蛾田间种群对各类杀虫剂均产生了不同程度的抗性。对有机磷类药剂的抗药性为1.74～31.1倍;对菊酯类药剂的抗药性为7.41～764倍;对阿维菌素类药剂则产生了5.60～4.06×10^4倍的抗性。通过离体和活体试验测定了药剂对小菜蛾头部乙酰胆碱酯酶（AChE）的抑制作用。敌敌畏和灭多威对通海抗性品系AChE离体和活体内的抑制中浓度（I50）分别是敏感品系的209、26.5倍和2.21、2.16倍;敌敌畏对通海小菜蛾种群的离体和活体内抑制中时间（IT50）小于敏感品系,分别是敏感品系的0.32和0.17倍;而灭多威对通海小菜蛾种群的离体和活体内抑制中时间（IT50）则大于敏感品系,分别是敏感品系的1.37和1.74倍。