小菜蛾对阿维菌素B_1抗药性选育及交互抗性

用阿维菌素B_1(abamectin)对小菜蛾敏感种群在室内进行抗性品系选育。经过25代连续汰选,获得抗性种群Laba-R,与选育前比较,抗性提高100倍。Laba-R种群在不接触任何药剂条件下饲养20代,抗性逐渐下降,很难恢复到选育前的敏感状态。抗性汰选前后分别测定10种药剂的剂量-死亡率毒力回归线,发现Laba-R抗性种群对乙酰甲胺磷、锐劲特、灭多威、敌敌畏不存在交互抗性;对溴氰菊酯、氯氰菊酯、杀虫双、巴丹和Bt的敏感性略有下降,但无明显交互抗性。活体增效剂试验表明,增效醚(PBO)和磷酸三苯酯(TPP)对阿维菌素B_1均有明显的增效作用,其中PBO的增效活性尤为显著,它能使对阿维菌素B_1产生100多倍抗药性的小菜蛾完全恢复其敏感性。说明多功能氧化酶解毒代谢增强可能是小菜蛾对阿维菌素B_1产生抗性的主导因素之一。     

不同种群小菜蛾乙酰胆碱酯酶性质研究

小菜蛾乙酰胆碱酯酶(AChE)的性质研究表明,不同种群小菜蛾成虫与幼虫AChE活性相比,差异极显著,成虫是幼虫的5～7倍;武汉种群小菜蛾成虫和幼虫AChE与底物的亲和力最小。小菜蛾谷胱甘肽鄄S鄄转移酶(GST)的性质研究表明,宣化、武汉、云南3个田间种群GST活性较高,明显高于台湾敏感品系;北京种群GST活性较低,与台湾敏感品系近似。此研究为进一步分析小菜蛾不同种群、不同虫态抗药性差异提供了依据。     

小菜蛾对阿维菌素B1抗药性选育及交互抗性

用阿维菌素B1（abamectin)对小菜蛾敏感种群在室内进行抗性品系选育。经过25代连续汰选，获得抗性种群Laba-R，与选育前比较，抗性提高100倍，La-ba-R种群在不接触任何药剂条件下饲养20代，抗性逐渐下降，很难恢复到选育前的敏感状态。抗性汰选前后分别测定10种药剂的剂量-死亡率毒力回归线，发现Laba-R抗性种群对乙酰甲胺磷、锐劲特、灭多威、敌敌畏不存在交互抗性；对溴氰菊酯、氯氰菊酯、杀虫双、巴丹和Bt的第三性略有下降，但无明显交互抗性。活性增效剂试验表明，增效醚（PBO）和磷酸三苯酯（TPP）对阿维菌素B1均有明显的增效作用，其中PBO的增效活性尤为显著，它能使对阿维菌素B1产生100多倍抗药性的小菜蛾完全恢复其敏感性，说明多功能氧化酶解毒代谢增强可能是小菜蛾对阿维菌素B1产生抗性的主导因素之一。     

云南省小菜蛾田间种群对氯虫苯甲酰胺的抗药性变化趋势

为掌握云南省不同菜区小菜蛾种群对氯虫苯甲酰胺的抗药性水平及年度变化规律,于2009—2013年间连续5年,采用浸叶法监测了滇中通海县、滇西弥渡县和滇西南临沧市小菜蛾田间种群对氯虫苯甲酰胺的敏感性;同时,对通海小菜蛾田间种群的F1代,测定了磷酸三苯酯(TPP)、增效醚(PBO)和顺丁烯二酸二乙酯(DEM)3种增效剂对氯虫苯甲酰胺的增效作用。结果表明:自2009年以来,通海小菜蛾种群的抗药性水平持续上升,抗性倍数从2009年的2.30倍,逐渐发展到2012年的47.79倍和2013年的43.05倍,达到中等抗性水平;弥渡小菜蛾种群的抗药性水平除了2010年达12.35倍外,其余均处于低水平抗性;临沧市小菜蛾种群的抗药性水平在1.01~4.60倍之间,处于低水平抗性。3种增效剂均对氯虫苯甲酰胺无显著增效作用。     

小菜蛾对杀虫药剂敏感品系的选育

通过单配选育的小菜蛾敏感品系对敌敌畏、灭多威、溴氰菊酯和杀虫双的敏感水平达到了选育目标,对4个药剂的敏感度LD_(50)值分别为0.0786、0.0356、0.0222和1.8949μg/头,并在生物学特性上与亲本无差异。该敏感品系可作为小菜蛾抗药性研究和新农药筛选的重要材料。     

我国部分地区田间小菜蛾种群对8种常用杀虫剂的抗性检测

采用浸叶法测定了来自5个地区的田间小菜蛾种群对8种杀虫剂的抗性水平。结果表明,5个地区小菜蛾种群对氯虫苯甲酰胺均产生了中等水平以上的抗性,江苏无锡和广东增城种群的抗性达1428.16倍和6642.12倍,为极高抗性水平;对丁醚脲均处于敏感或敏感性降低水平。5个地区的小菜蛾种群对甲氨基阿维菌素、虫螨腈、S-茚虫威、虫酰肼和唑虫酰胺等5种药剂的敏感性各异,大多处于敏感或敏感性降低水平,但也有些地区产生了中等水平的抗性。本研究结果明确了我国部分地区对小菜蛾抗药性情况,可为小菜蛾的抗性治理提供参考。     

氯虫苯甲酰胺、阿维菌素与苏云金芽胞杆菌桶混对不同地区抗性小菜蛾的防治效果

为了解云南通海、湖北武汉、海南海口田间小菜蛾种群对氯虫苯甲酰胺、阿维菌素、苏云金芽胞杆菌抗药性现状及其桶混的田间防治效果,为小菜蛾抗性治理策略提供参考,推进化学农药减量控害。采用叶片浸渍法和田间小区试验对以上3种杀虫剂进行抗药性测定和田间药效试验。结果表明,3个地区小菜蛾田间种群均对阿维菌素产生了高水平抗性,抗药性倍数为276.0~1062.0倍,对氯虫苯甲酰胺抗药性达到中等至高水平抗性,抗药性倍数为60.0~671.0倍,对苏云金芽胞杆菌表现为中等及以下水平抗性,抗药性倍数为5.1~15.2倍。田间防治效果和抗性水平呈现出一定的相关性,苏云金芽胞杆菌药后7 d均达到70%以上,而氯虫苯甲酰胺、阿维菌素单剂药后7 d防治效果均达不到60%。氯虫苯甲酰胺、阿维菌素和苏云金芽胞杆菌桶混处理的田间防治效果在以上地区分别为88.70%和81.50%,防治效果较好,桶混处理防效与各单剂相比差异极显著。因此,建议可以桶混、轮换使用苏云金芽胞杆菌,以提高对小菜蛾的持续控制效果。     

武汉地区小菜蛾对溴氰菊酯的抗性回复及交互抗性

与小菜蛾敏感品系相比,武汉市张家湾小菜蛾田间种群的F₁、F₄和F₇,代对溴氰菊酯的抗性指数分别为362.79、30.78和10.91倍,抗性回复显著。用浸叶法测定Bt、抑太保和杀虫双制剂对两个小菜蛾种群的毒力,证明小菜蛾对这3类药剂与溴氰菊酯间无交互抗性。研究结果可为小菜蛾抗药性治理方案的制订提供依据。     

小菜蛾对唑虫酰胺的抗性监测、抗性生化机制及交互抗性

为了明确小菜蛾Plutella xylostella对唑虫酰胺的抗性特征,采用生物生化方法测定了江西省5个蔬菜产区小菜蛾田间种群对唑虫酰胺的抗性水平,并研究了小菜蛾唑虫酰胺抗性品系对其它药剂的交互抗性和生化抗性机制。结果显示,分宜县和高安市小菜蛾田间种群对唑虫酰胺尚未产生明显抗性,永丰县、德安县和余江县小菜蛾种群对唑虫酰胺产生了低水平的抗性,抗性倍数为5.20~8.20倍;小菜蛾唑虫酰胺抗性品系对阿维菌素、氯虫苯甲酰胺、氟虫双酰胺和茚虫威有中低水平的交互抗性,抗性倍数分别为11.72、3.44、2.77和2.20倍,而对溴虫腈、定虫隆和丁醚脲无交互抗性;增效剂磷酸三苯酯和胡椒基丁醚对小菜蛾唑虫酰胺抗性品系均有显著增效作用,增效倍数分别为3.42倍和2.64倍;唑虫酰胺抗性品系的酯酶和多功能氧化酶活性均显著提高,分别为敏感品系的2.18倍和1.64倍。研究表明,小菜蛾对唑虫酰胺产生抗性可能与酯酶和多功能氧化酶活性的升高有关。     

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。     

Toxicological and biochemical characterizations of AChE in Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae)

The toxicological and biochemical characteristics of acetylcholinesterases (AChE) in the resistant and susceptible strains (SS) of Liposcelis bostrychophila were investigated. The two resistant strains were the dichlorvos-resistant strain (DDVP-R) and the phosphine-resistant strain (PH₃-R) with resistance ratios of 22.36 and 4.51, respectively. Compared to their susceptible counterpart, the AChE activity per insect and the specific activity of AChE in DDVP-R and PH₃-R were significantly higher. There were also significant kinetic differences between DDVP-R and PH₃-R. The apparent Michaelis-Menten constant (K_m) for acetylthiocholine iodide (ATChI) was obviously lower in SS than that in PH₃-R, indicating a higher affinity to the substrate ATChI in the susceptible strains. The affinity for the substrate ATChI in DDVP-R and SS were not significantly different. The V_max value of the PH₃-R was significantly greater when compared to the V_max for the SS suggesting a possible over expression of AChE in this resistant strain. The inhibition of AChE to insecticide exposure in vitro revealed that all six insecticides were inhibitory for the extracted AChE’s. Based on the I₅₀ values, AChE of the SS were more sensitive to dichlorvos, paraoxon-ethyl, malaoxon and demeton-S-methyl than those of the two resistant strains. As for carbaryl and eserine, the PH₃-R suggested a significantly higher I₅₀s compared to the susceptible strain, while, no significant differences were found between SS and DDVP-R.     

Triazophos resistance mechanisms in the rice stem borer (Chilo suppressalis Walker)

A field population of the rice stem borer (Chilo suppressalis Walker) with 203.3-fold resistance to triazophos was collected. After 8-generation of continuous selection with triazophos in laboratory, resistance increased to 787.2-fold, and at the same time, the resistance to isocarbophos and methamidophos was also enhanced by 1.9- and 1.4-fold, respectively, implying some cross-resistance between triazophos and these two organophosphate insecticides. Resistance to abamectin was slightly enhanced by triazophos selection, and fipronil and methomyl decreased. Synergism experiments in vivo with TPP, PBO, and DEM were performed to gain a potential indication of roles of detoxicating enzymes in triazophos resistance. The synergism results revealed that TPP (SR, 1.92) and PBO (SR 1.63) had significant synergistic effects on triazophos in resistant rice borers. While DEM (SR 0.83) showed no effects. Assays of enzyme activity in vitro demonstrated that the resistant strain had higher activity of esterase and microsomal O-demethylase than the susceptible strain (1.20- and 1.30-fold, respectively). For glutathione S-transferase activity, no difference was found between the resistant and the susceptible strain when DCNB was used as substrate. However, 1.28-fold higher activity was observed in the resistant strain when CDNB was used. These results showed that esterase and microsomal-O-demethylase play some roles in the resistance. Some iso-enzyme of glutathione S-transferase may involve in the resistance to other insecticides, for this resistant strain was selected from a field population with multiple resistance background. Acetylcholinesterase as the triazophos target was also compared. The results revealed significant differences between the resistant and susceptible strain. The V_max and K_m of the enzyme in resistant strain was only 32 and 65% that in the susceptible strain, respectively. Inhibition tests in vitro showed that I₅₀ of triazophos on AChE of the resistant strain was 2.52-fold higher. Therefore, insensitive AChE may also involved in triazophos resistance mechanism of rice stem borer.     

甜菜夜蛾敏感品系的获得及其对12种杀虫剂的敏感基线

以高效氯氰菊酯为筛选药剂,通过室内单对汰选获得了甜菜夜蛾敏感品系,并采用浸叶法和点滴法测定该敏感品系对甲氨基阿维菌素苯甲酸盐、氯虫苯甲酰胺等12种常用药剂的敏感基线。浸叶法测得该品系对供试药剂的敏感性由高到低依次为:甲氨基阿维菌素苯甲酸盐(LC50为0.0340 mg/L)、茚虫威、氟啶脲、甲氧虫酰肼、氯虫苯甲酰胺、氟虫双酰胺、高效氯氰菊酯、虫酰肼、多杀菌素、毒死蜱、虫螨腈、灭多威(124.0482mg/L)。点滴法测得12种杀虫剂LD50由小到大依次为:高效氯氰菊酯、茚虫威、甲氧虫酰肼、甲氨基阿维菌素苯甲酸盐、虫酰肼、毒死蜱、多杀菌素、氯虫苯甲酰胺、虫螨腈、氟虫双酰胺、灭多威、氟啶脲。结果表明,该敏感基线可用于甜菜夜蛾的抗药性监测。     

Resistance mechanisms and associated mutations in acetylcholinesterase genes in Sitobion avenae (Fabricius)

Wheat aphid, Sitobion avenae (fabricius), is one of the most important wheat pests and has been reported to be resistant to commonly used insecticides in China. To determine the resistance mechanism, the resistant and susceptible strains were developed in laboratory and comparably studied. A bioassay revealed that the resistant strain showed high resistance to pirimicarb (RR: 161.8), moderate reistance to omethoate (32.5) and monocrotophos (33.5), and low resistance to deltamethrin (6.3) and thiodicarb (5.5). A biochemistry analysis showed that both strains had similar glutathione-S-transferase (GST) activity, but the resistant strain had 3.8-fold higher esterase activity, and its AChE was insensitive to this treatment. The I₅₀ increased by 25.8-, 10.7-, and 10.4-folds for pirimicarb, omethoate, and monocrotophos, respectively, demonstrating that GST had not been involved in the resistance of S. avenae. The enhanced esterase contributed to low level resistance to all the insecticides tested, whereas higher resistance to pirimicarb, omethoate, and monocrotophos mainly depended on AChE insensitivity. However, the AChE of the resistant strain was still sensitive to thiodicarb (1.7-fold). Thus, thiodicarb could be used as substitute for control of the resistant S. avenae in this case. Furthermore, the two different AChE genes cloned from different resistant and susceptible individuals were also compared. Two mutations, L436(336)S in Sa.Ace1 and W516(435)R in Sa.Ace2, were found consistently associated with the insensitivity of AChE. They were thought to be the possible resistance mutations, but further work is needed to confirm this hypothesis.     

三种植物次生物质对B型烟粉虱羧酸酯酶活性及其对药剂敏感度的影响

采用人工饲料添加法,研究了不同浓度的槲皮素、2-十三烷酮和葫芦素B 3种植物次生物质对B型烟粉虱Bemisia tabaci羧酸酯酶(CarE)活性的影响,同时比较研究了用3种植物次生物质处理后敌敌畏、脱叶磷、灭多威、乐果和氧乐果5种药剂对CarE 的抑制中浓度(I50)的变化。结果表明: 0.01~1.0 mg/mL的槲皮素对B型烟粉虱成虫CarE活性均具有明显的诱导增加作用,最高为对照的4.32倍; 0.1和0.5 mg/mL的2-十三烷酮处理使CarE活性比对照分别下降了22%和58%; 0.75~30.0 mg/L的葫芦素B对烟粉虱CarE活性均表现为抑制作用;用1.0 mg/mL的槲皮素处理24 h后,敌敌畏和脱叶磷对烟粉虱CarE的I50值分别增加为对照的20.05和3.16倍; 3.75 mg/L 的葫芦素B处理后,敌敌畏和灭多威对CarE 的I50值分别增加为对照的25.94、2.45倍; 1.0 mg/mL的2-十三烷酮处理后敌敌畏、脱叶磷和乐果对CarE 的I50值分别降低了89%、83%和90%。     

Insensitivity of acetylcholinesterase in a field strain of the fall armyworm, Spodoptera frugiperda (J.E. Smith)

Acetylcholinesterase (AChE) was purified from adult heads of the fall armyworm (Spodoptera frugiperda) by using a two-step procedure involving gel filtration on a Sephadex G-200 column and affinity chromatography on a procainamide-ECH Sephadex 4B column. Both susceptible and field strains possessed two AChE isozymes, namely, AChE-1 and AChE-2, with subunit molecular weights of 63.7 and 66.1 kDa. The purified AChE had an apparent K_m value of 33.5 μM and a V_max of 7.07 μmol/min/mg protein in the susceptible strain. The apparent K_m and the V_max were 2.2- and 2.0-fold higher, respectively, in the field strain than in the susceptible strain. The purified AChE from the field strain was 17- to 345-fold less sensitive than that from the susceptible strain to inhibition by carbamates (carbaryl, eserine, methomyl, and bendiocarb) and organophosphates (methyl paraoxon and paraoxon), insensitivity being highest toward carbaryl. The results further support the notion that insensitive AChE played an important role in the insecticide resistance observed in the field strain.     

Communication to the Editor Insecticide Resistance in a Strain of Aphis gossypii from Southern France

A strain (R) of Aphis gossypii from Southern France was found to be resistant to several insecticides, particularly to pirimicarb, as compared to a susceptible strain (S). Resistance levels were determined by biological tests, and the highest resistance factor (1350) was for pirimicarb. Resistance was mainly restricted to anticholinesterase inhibitors. Use of synergists, DEF and PB, suggested that resistance mechanisms based on detoxification were involved to a minor extent, since a good correlation was observed between I₅₀ values and k_i values of AChE and in-vivo bioassay data. The two strains differed in esterase activity, with a 27·7-fold increase in the R strain. Resolution of esterases by polyacrylamide gel electrophoresis showed different patterns in the S and R strains, and two isozymes were less sensitive to pirimicarb in the S strain; however, no in-vitro degradation of [¹⁴C]pirimicarb was observed. These data suggest that the main mechanism of resistance was through a decrease in the sensitivity of the target, AChE, to the insecticides. © 1997 SCI.     

Toxicological and biochemical characterization of coumaphos resistance in the San Roman strain of Boophilus microplus (Acari: Ixodidae)

The San Roman strain of the southern cattle tick, Boophilus microplus, collected from Mexico was previously reported to have a high level of resistance to the organophosphate acaricide coumaphos. An oxidative detoxification mechanism was suspected to contribute to coumaphos resistance in this tick strain, as coumaphos bioassay with piperonyl butoxide (PBO) on larvae of this resistant strain resulted in enhanced coumaphos toxicity, while coumaphos assays with PBO resulted in reduced toxicity of coumaphos in a susceptible reference strain. In this study, we further analyzed the mechanism of oxidative metabolic detoxification with synergist bioassays of coroxon, the toxic metabolite of coumaphos, and the mechanism of target-site insensitivity with acetylcholinesterase (AChE) inhibition kinetics assays. Bioassays of coroxon with PBO resulted in synergism of coroxon toxicity in both the San Roman and the susceptible reference strains. The synergism ratio of PBO on coroxon in the resistant strain was 4.5 times that of the susceptible strain. The results suggested that the cytP450-based metabolic detoxification existed in both resistant and susceptible strains, but its activity was significantly enhanced in the resistant strain. Comparisons of AChE activity and inhibition kinetics by coroxon in both susceptible and resistant strains revealed that the resistant San Roman strain had an insensitive AChE, with a reduced phosphorylation rate, resulting in a reduced bimolecular reaction constant. These data indicate a mechanism of coumaphos resistance in the San Roman strain that involves both insensitive AChE and enhanced cytP450-based metabolic detoxification.     

兰州市桃蚜抗药性监测及治理对策研究

以甘肃省宕昌县桃蚜为敏感种群,测定了兰州、永登等地桃蚜对6种杀虫剂抗药性。结果表明兰州市安宁区桃蚜对溴氰菊酯已产生低水平抗性(6.84倍),对氰戊菊酯则处于耐药力增高或敏感性降低阶段,对灭多威、敌敌畏、氧乐果和乐果已显示出早期抗性;永登县桃蚜对溴氰菊酯和氰戊菊酯处于敏感性降低阶段,对灭多威、敌敌畏、氧乐果和乐果仍属敏感阶段;皋兰县和榆中县桃蚜对上述6种杀虫剂则处于敏感阶段。用酶抑制剂进行增效作用测定结果显示,兰州地区桃蚜的抗药性与羧酸酯酶和多功能氧化酶有关。针对兰州市桃蚜的抗药性现状和抗性机制,提出了以建立抗性监测制度、合理用药为主的抗性治理对策。