棉铃虫核型多角体病毒与化学杀虫剂和卵磷脂混用的增效作用

棉铃虫核型多角体病毒(HaNPV)分别与三氟氯氰菊酯、溴氰菊酯、氰戊菊酯、灭净菊酯、灭多威、辛硫磷、甲基对硫磷和乙酰甲胺磷等化学杀虫剂混合饲喂棉铃虫幼虫,统计致死中浓度LC₅₀,计算增效比,测定虫体内与抗性有关的三种重要酶：多功能氧化酶(MFO)、羧酸酯酶(CarE)、乙酰胆碱酯酶(AChE)的活性。研究大豆卵磷脂对HaNPV致病性的影响。结果表明：HaNPV与化学杀虫剂混合饲喂抗性棉铃虫,生测统计增效比均大于1.0,特别是病毒与甲基对硫磷混用,增效比更是达到3.53,表现出良好的增效作用。混剂感染抗性棉铃虫,虫体内MFO的活性比化学杀虫剂单用时降低3～12倍,CarE和AChE的活性也比化学杀虫剂单用时低,HaNPV明显抑制了化学杀虫剂对MFO和CarE的诱导作用。HaNPV与大豆卵磷脂混用,提高了HaNPV对棉铃虫的感染致死率,缩短了致死中时间(LT₅₀)。     

21种杀虫剂和3种植物次生物质对杨扇舟蛾各组织谷胱甘肽S-转移酶的抑制作用

为了比较杨扇舟蛾Clostera anachoreta (Fabricius)各组织谷胱甘肽S 转移酶（GSTs）的差异,利用分光光度酶动力学的方法,研究了21种杀虫剂和3种植物次生物质对杨扇舟蛾4个组织（中肠、脂肪体、头部和体壁）GSTs活性的体外影响。结果表明:21种杀虫剂和3种植物次生物质对杨扇舟蛾4个组织GSTs活性的抑制作用不同。毒死蜱、氟虫腈、槲皮素和单宁酸对于杨扇舟蛾头GSTs活性抑制作用最强;槲皮素和单宁酸对中肠GSTs活性的抑制作用最强;单宁酸对脂肪体GSTs活性的抑制作用最强;辛硫磷、高效氯氟氰菊酯、溴氰菊酯和硫丹对皮GSTs活性的抑制作用最强。杨扇舟蛾4个组织GSTs对杀虫剂和植物次生物质敏感性存在的这种差异,可能是由于其在同工酶组成上的差异造成的。     

植物次生物质和杀虫剂对分月扇舟蛾谷胱甘肽S-转移酶的抑制作用

本论文采用分光光度计法研究了植物次生物质和杀虫剂对分月扇舟蛾Closteraanastomosis(L.)谷胱甘肽S-转移酶(GSTs)的体外抑制作用。结果表明各植物次生物质和杀虫剂对分月扇舟蛾GSTs活性的体外抑制作用存在差异。当植物次生物质和杀虫剂终浓度为8.34×10-5mol/L时,槲皮素和单宁酸对分月扇舟蛾GSTs活性抑制作用最强,分别为64.41%和58.61%;三唑磷、毒死蜱、辛硫磷、氟铃脲、氟虫腈和哒螨灵都有较强的抑制作用,对GSTs活性抑制率超过20%;氧化乐果、水胺硫磷、丙溴磷、马拉硫磷、灭多威、联苯菊酯、高效氯氰菊酯、甲氰菊酯、高效氯氟氰菊酯、吡虫啉和啶虫脒对分月扇舟蛾GSTs有中等抑制作用;其他杀虫剂对分月扇舟蛾GSTs有较弱(或没有)抑制作用。此外,在一定的浓度范围内,槲皮素、单宁酸和辛硫磷对分月扇舟蛾GSTs活性的抑制作用存在明显的剂量效应关系。槲皮素、单宁酸和辛硫磷对分月扇舟蛾GSTs的抑制中浓度分别为2.19×10-5,2.62×10-5,1.49×10-4mol/L。因此,此研究明确了槲皮素和单宁酸作为防治分月扇舟蛾的新型防治剂或增效剂具有很好的潜力。     

亚洲小车蝗痘病毒增效因子的初步研究

OaEPV经2×SDS包涵体碱性裂解缓冲液裂解,离心,分别用上清液及沉淀与绿僵菌孢子混合感染黄胫小车蝗,上清液的增效活性比沉淀大2.5倍.用三种不同方法(2×SDS包涵体碱性裂解液法,0.02 mol/L NaOH裂解法,8 mol/L尿素裂解法)裂解OaEPV所得蛋白液与绿僵菌混用,生测结果表明,包涵体裂解液法制备所得蛋白增效活性最高,NaOH裂解法次之,尿素裂解法制备的蛋白几乎没有增效活性.将OaEPV用包涵体碱性裂解液裂解后,用葡聚糖G-200 凝胶柱层析进行分离,出现两个洗脱峰,这两个峰的洗脱液浓缩后进行生物测定,初步表明增效作用主要为第二个峰的蛋白片段.经SDS-聚丙烯酰胺凝胶电泳,第二个峰的蛋白片段的分子量为40 kDa左右.     

亚洲小车蝗痘病毒增效因子的初步研究

OaEPV经2×SDS包涵体碱性裂解缓冲液裂解,离心,分别用上清液及沉淀与绿僵菌孢子混合感染黄胫小车蝗,上清液的增效活性比沉淀大2.5倍。用三种不同方法(2×SDS包涵体碱性裂解液法,0.02 mol/L NaOH裂解法,8 mol/L尿素裂解法)裂解OaEPV所得蛋白液与绿僵菌混用,生测结果表明,包涵体裂解液法制备所得蛋白增效活性最高,NaOH裂解法次之,尿素裂解法制备的蛋白几乎没有增效活性。将OaEPV用包涵体碱性裂解液裂解后,用葡聚糖G-200凝胶柱层析进行分离,出现两个洗脱峰,这两个峰的洗脱液浓缩后进行生物测定,初步表明增效作用主要为第二个峰的蛋白片段。经SDS-聚丙烯酰胺凝胶电泳,第二个峰的蛋白片段的分子量为40kDa左右。     

天津地区家蝇抗药性水平及与两种解毒酶的关系

用点滴法对采自天津市7个郊区县的7个不同生境野外家蝇种群的抗药性进行了测定并与实验室内的相对敏感种群进行比较;对不同地区家蝇种群进行了羧酸酯酶（carboxylesterase, CarE）和谷胱甘肽S-转移酶（glutathione S-transferase, GSTs）活性检测。结果表明,不同家蝇种群对DDVP、高效氯氰菊酯和残杀威的抗性倍数不同,对DDVP抗性最高为18.563倍,最低为1.885倍;对高效氯氰菊酯最高为14.071倍,最低为1.071倍;对残杀威抗性倍数最高为7.499倍,最低为1.071倍。从CarE平均比活力看,室外家蝇种群CarE的比活力均高于室内相对敏感种群的比活力,CarE活性的分布在敏感种群和不同地区野外种群间具有明显的重叠现象。天津不同地区F₂代家蝇GSTs的比活力抗性种群普遍高于室内相对敏感种群,大约在2～4倍之间,不同地区间也具有比较大的差异,而抗药性高的种群GSTs活性也高,GSTs活性变化与不同种群抗性差异是相符的。     

河北转Bt基因棉田棉铃虫对杀虫剂的抗性及相关酶活性的变化

为明确河北省推广种植植转Bt基因抗虫棉（简称Bt棉）后, 棉铃虫Helicoverpa armigera (Hübner)对常用杀虫剂的抗药性水平及其生化机理, 2011-2012年采用点滴法对保定南郊、 沧州南皮、 邢台巨鹿3个地区的田间种群以及敏感种群进行了室内毒力测定, 并采用生化分析法对4个种群相关的羧酸酯酶（carboxylesterase, CarE）、 谷胱甘肽S 转移酶(glutathione S-transferases, GSTs)和乙酰胆碱酯酶(acetylcholinesterase, AChE)的活性进行了研究。结果表明: 3个田间种群对高效氯氰菊酯和氰戊菊酯处于中至高抗水平, 抗性倍数为20.02~73.70倍; 对灭多威处于低至中抗水平, 抗性倍数为6.27~11.84倍; 对高效氯氟氰菊酯(抗性倍数: 1.07~4.20倍), 辛硫磷、 毒死蜱和马拉硫磷(抗性倍数: 1.00~2.69倍), 以及氯虫苯甲酰胺（抗性倍数: 2.00~3.67倍）均处于敏感水平。3个田间种群的CarE, GSTs和AChE活性分别是敏感种群的1.06~1.23, 1.20~1.63和1.15~1.23倍, 这可能与其对高效氯氰菊酯、 氰戊菊酯和灭多威产生的抗性有关。     

杀虫剂对三角新小卷蛾的毒力与田间防效

研究了常用杀虫剂对三角新小卷蛾Olethreutes leucaspis Meyrick的室内毒力与田间防效.按照毒力降低的顺序,所测定杀虫剂对三角新小卷蛾毒力顺序为甲氨基阿维菌素苯甲酸盐>氟虫腈>三氟氯氰菊酯>溴氰菊酯>阿维菌素>、高效氯氰菊酯>氟虫脲>氰戊菊酯>氟啶脲>毒死蜱>敌百虫.但在田间条件下,各试验药剂均能有效控制三角新小卷蛾的为害.结果表明,敌百虫对三角新小卷蛾的毒力最低,LC50为186.16 mg·L-1,甲氨基阿维菌素苯甲酸盐和氟虫腈的毒力最高,LC50分别为0.67、0.83 mg·L-1,是敌百虫毒力的279.52、224.86倍;三氟氯氰菊酯、溴氰菊酯、阿维菌素、高效氯氰菊酯、氟虫脲和氰戊菊酯亦具有较高的毒力,LC50分别为1.24、1.37、1.60、3.75、5.17、6.71 mg·L-1;毒死蜱和氟啶脲的毒力低于其它药剂.各试验药剂均能有效控制三角新小卷蛾的为害.     

化学杀虫剂对昆虫病原线虫侵染韭菜迟眼蕈蚊能力的影响

【目的】为提高昆虫病原线虫对韭菜迟眼蕈蚊Bradysia odoriphaga的防治效果,将昆虫病原线虫与环境友好型化学杀虫剂混用是一条有效途径。【方法】本研究测试了70%吡虫啉水分散颗粒剂、40%毒死蜱乳油和4.5%高效氯氰菊酯乳油对昆虫病原线虫Heterorhabdits bacteriophora Taishan strain H06品系、Steinernema carpocapsae strain SF-SN和All品系存活及侵染率的影响,及低剂量化学杀虫剂与昆虫病原线虫混用对韭蛆3龄幼虫的作用效果。【结果】高效氯氰菊酯(含量为2.00、0.40、0.20和0.10μg·mL-1)和吡虫啉(25.00、5.00、2.50和1.25μg·mL-1)对H.bacteriophora H06和S.carpocapsae All的存活无显著影响,3品系线虫毒死蜱(8.00μg·mL-1)对3品系线虫的致死率均显著高于对照;不同浓度的毒死蜱对3品系线虫的致死率存在显著差异。3种药剂分别与3品系线虫混合后处理韭蛆,韭蛆的死亡率明显高于线虫和杀虫剂单用处理。药后3 d,SF-SN与毒死蜱(8.00μg·mL-1)、吡虫啉(25.00μg·mL-1)和高效氯氰菊酯(2.00μg·mL-1)混合处理韭蛆,分别比单用杀虫剂提高防效34.20%、21.18%、54.99%,优于另外两种线虫与3种药剂混用的效果。【结论】供试线虫中,SF-SN品系与上述杀虫剂联合防治韭蛆效果最好。     

两个广西草地贪夜蛾种群对常用杀虫剂的敏感性测定

为了解入侵广西的草地贪夜蛾Spodoptera frugiperda对不同杀虫剂的敏感性,为筛选该虫的有效防治药剂,以及为该虫的抗药性监测提供科学依据。本研究用浸叶法分别测定了田阳种群对13种杀虫剂和南宁种群对5种杀虫剂的敏感性,并比较了两个种群对5种杀虫剂的敏感性差异。结果表明,田阳种群对13种杀虫剂的敏感性依次为:甲氨基阿维菌素苯甲酸盐多杀菌素氯虫苯甲酰胺虫螨腈溴氰菊酯阿维菌素甲氰菊酯氟氯氰菊酯茚虫威呋虫胺毒死蜱高效氯氰菊酯吡虫啉,其中对甲氨基阿维菌素苯甲酸盐、多杀菌素、氯虫苯甲酰胺的敏感性较高,LC_(50)值分别为0.0015、0.0062、0.0075 mg a.i/L,毒力指数分别为480.47、116.24、96.09,其次是虫螨腈、溴氰菊酯、阿维菌素,LC_(50)值分别为0.0296、0.0590、0.0619 mg a.i/L,毒力指数分别为:24.35、12.22、11.64,对其他药剂的敏感性较低,LC_(50)值在0.2544～0.7207 mg a.i/L,毒力指数在1～2.83,除对溴氰菊酯和阿维菌素、甲氰菊酯和氟氯氰菊酯、呋虫胺和毒死蜱、高效氯氰菊酯和吡虫啉的敏感性差异不显著外,对其它药剂差异显著。南宁种群对5种杀虫剂的敏感性依次为:氯虫苯甲酰胺溴氰菊酯氟氯氰菊酯甲氰菊酯高效氯氰菊酯,LC_(50)值分别为0.0142、0.0413、0.0792、0.2081和0.5947 mg a.i/L,毒力指数分别为:41.88、14.40、7.51、2.86和1.00,对各药剂的敏感性均差异显著。南宁和田阳种群对氯虫苯甲酰胺、溴氰菊酯、氟氯氰菊酯、甲氰菊酯和高效氯氰菊酯的敏感性差异均较大,相对毒力指数分别在1.00～41.88和1.00～79.25。两个种群对同种杀虫剂的敏感性也有所差异,除对高效氯氰菊酯的敏感性差异不显著外,对其余药剂的敏感性均差异显著。     

Current Perspectives on Plague Vector Control in Madagascar: Susceptibility Status of Xenopsylla cheopis to 12 Insecticides

Plague is a rodent disease transmissible to humans by infected flea bites, and Madagascar is one of the countries with the highest plague incidence in the world. This study reports the susceptibility of the main plague vector Xenopsylla cheopis to 12 different insecticides belonging to 4 insecticide families (carbamates, organophosphates, pyrethroids and organochlorines). Eight populations from different geographical regions of Madagascar previously resistant to deltamethrin were tested with a World Health Organization standard bioassay. Insecticide susceptibility varied amongst populations, but all of them were resistant to six insecticides belonging to pyrethroid and carbamate insecticides (alphacypermethrin, lambdacyhalothrin, etofenprox, deltamethrin, bendiocarb and propoxur). Only one insecticide (dieldrin) was an efficient pulicide for all flea populations. Cross resistances were suspected. This study proposes at least three alternative insecticides (malathion, fenitrothion and cyfluthrin) to replace deltamethrin during plague epidemic responses, but the most efficient insecticide may be different for each population studied. We highlight the importance of continuous insecticide susceptibility surveillance in the areas of high plague risk in Madagascar.     

杀虫药剂和植物次生性物质对棉铃虫羧酸酯酶的诱导作用

棉铃虫Helzcoverpa armigera中肠羧酸酯酶(CarEs)比活力随幼虫发育阶段呈有规律的变化。5日龄以前CarEs比活力增长比较缓慢,5日龄以后Cares比活力快速增长,8日龄开始CarEs比活力下降,直到预蛹期,CarEs比活力又开始上升。用聚丙烯酰胺凝胶电泳分离到的9条同功酶带中,E2、E4、E5、E6、E7和E9对β-乙酸萘酯(β-NA)的水解活性高于对a—乙酸萘酯(a-NA),E1、E3、和E8对上述两种底物的水解活性正好相反,对a-NA活性高于对β-NA。低剂量的对硫磷、马拉硫磷、倍硫磷、增效磷(SVl)、灭多威和溴氰菊酯对棉铃虫中肠CarEs比活力和对底物的亲和力具有明显的影响。药剂处理后48 h,Cares的比活力明显降低,对底物的亲和力则与药剂的种类有关。马拉硫磷处理后48h,在观察到的6条主要同功酶带中,E3的活性明显降低,其次是E6、E2和E1;而E5的活性则明显升高,斟的活性也有所升高。用含0.01%的芸香苷、2-十三烷酮和槲皮素的人工饲料饲养棉铃虫经2代或7代后,CarEs比活力均明显升高。     

Determination of the resistance to organophosphate, carbamate, and pyrethroid insecticides in Panamanian Anopheles albimanus (Diptera: Culicidae) mosquitoes

Introduction. The susceptibility of Anopheles albimanus to organophosphates, carbamates and pyrethroid insecticides was unknown in the Panama communities of Aguas Claras, Pintupo and Puente Bayano, located in the Amerindian Reservation of Madungandi. This region is considered a malaria transmission area, where An. albimanus is the main vector. Objective. The resistance to organophosphate insecticides, carbamates and pyrethroids was evaluated in field populations of the Anopheles albimanus in Panama. Materials and methods. Progeny of An. albimanus collected in three localities in the indigenous Madugandi region were exposed to bioassays of susceptibility to organophosphate insecticides (fenitrothion, malathion and chlorpyrifos), the carbamate (propoxur) and pyrethroids (deltamethrin, lambdacyhalothrin, cyfluthrin and cypermethrin). The protocols were in accordance with those established for adult mosquitoes by World Health Organization. Results. The three strains of the An. albimanus were resistant to the pyrethroid insecticides deltamethrin, lambdacyhalothrin, cyfluthrin and cypermethrin. Susceptibility remained for the organophosphate insecticides fenitrothion, malathion, chlorpyrifos, and the carbamate insecticide propoxur. Conclusion. The results provided important information to the vector control program, contributing to the application of new strategies on the use of insecticides, and thereby lengthening the life of the insecticide in use.     

棉铃虫的谷胱甘肽S—转移酶(GSTs)：杀虫药剂和植物次生性物质的诱导与GSTs对杀虫药剂的代谢

棉铃虫Helicoverpa armigera(Hubner)中肠谷胱甘肽S-转移酶(GSTs)对甲基对硫磷和灭多威的代谢能力明显高于对马来酸二乙酯(DEM)和两个混剂。LD₅剂量的对硫磷和灭多威对棉铃虫3龄幼虫GSTs的活性均没有诱导增加的影响,用LD₅₀的选择剂量仅对硫磷组GSTs活性增加15%。用含0.01%的芸香苷、2-十三烷酮和槲皮素的人工饲料饲养棉铃虫经1～4代后,GSTs活性提高4～18倍。3种植物次生性物质诱导组对灭多威和溴氰菊酯的敏感度均没有明显的变化,而槲皮素组对甲基对硫磷的敏感度则降低近一半,芸香苷和2-十三烷酮组对甲基对硫磷的敏感度略有降低。这种对甲基对硫磷敏感度的变化可能与上述GSTs活性的变化有关。     

辛硫磷和溴氰菊酯混剂对家蝇抗性发展的影响

以家蝇(Musca domestica vicina Macquart)为试虫,用辛硫磷溴氰菊酯单剂及不同配比的混剂进行汰选试验。所有混剂选育的家蝇抗性发展都很缓慢,而单剂抗性发展都很快。增效试验表明,辛硫磷与溴氰菊酯混配有明显增效作用,特别是对抗性品系。生化分析结果表明,对澳氰菊酯的抗性发展与酯酶的酶活升高有关。对辛硫磷抗性发展与多功能氧化酶的酶活升高和乙酰胆碱酯酶敏感性降低有关。混剂选育的家蝇其对单剂的敏感性的变化及酶系的变化,随着混剂的配比而变化。     

Lethal and sublethal effects of insecticide residues on Orius insidiosus (Hemiptera: Anthocoridae) and Geocoris punctipes (Hemiptera: Lygaeidae)

Laboratory-reared predators, the insidious flower bug, Orius insidiosus (Say), and big-eyed bug Geocoris punctipes (Say), were exposed to 10 insecticides, including three newer insecticides with novel modes of action, using a residual insecticide bioassay. These species are important predators of several economic pests of cotton. Insecticides tested were: azinphos-methyl, imidacloprid, spinosad, tebufenozide, fipronil, endosulfan, chlorfenapyr, cyfluthrin, profenofos, and malathion. There was considerable variation in response between both species tested to the insecticides. Tebufenozide and cyfluthrin were significantly less toxic to male O. insidiosus than malathion. Tebufenozide was also significantly less toxic to female O. insidiosus than malathion. Imidacloprid, tebufenozide, and spinosad were significantly less toxic to male G. punctipes than chlorfenapyr, endosulfan, and fipronil. Spinosad, tebufenozide, and azinphos-methyl were significantly less toxic to female G. punctipes than fipronil and endosulfan. Fecundity of O. insidiosus was significantly greater in the spinosad treatment compared with other treatments including the control. Consumption of bollworm, Helicoverpa zea (Boddie), eggs by O. insidiosus was significantly lower in the fipronil, profenofos, and cyfluthrin treatments compared with other treatments including the control. Consumption of H. zea eggs by G. punctipes was significantly lower in the malathion, profenofos, endosulfan, fipronil, azinphos-methyl, and imidacloprid treatments compared with the control. Egg consumption by G. punctipes was not significantly different in the tebufenozide treatment compared with the control. The lower toxicity of spinosad to G. punctipes is consistent with other reports. Based on these results, the following insecticides are not compatible with integrated pest management of cotton pests: malathion, endosulfan, profenofos, fipronil, and cyfluthrin; while imidacloprid, tebufenozide, azinphos-methyl, and spinosad should provide pest control while sparing beneficial species.     

七种抑制剂对两种白蚁谷胱甘肽S-转移酶活性抑制作用的比较

利用分光光度酶动力学方法,确定了白蚁谷胱甘肽S-转移酶（GSTs）的最适反应条件,并进一步研究了7种抑制剂对黑翅土白蚁Odontotermes formosanus (Shiraki)和黑胸散白蚁Reticulitermes chinensis Snyder GSTs活性的体外影响。结果表明：白蚁GSTs测定的最适反应条件为pH 6.5,温度25℃,最适反应时间2 min。黑翅土白蚁GSTs的米氏常数(K_mCDNB和K_mGSH)分别为0.11±0.02 mmol/L和0.81±0.16 mmol/L,最大反应速度(V_maxCDNB和V_maxGSH)分别为425.92±19.67 nmol/(min·mg)和534.86±39.05 nmol/(min·mg)。黑胸散白蚁GSTs的米氏常数(K_mCDNB和K_mGSH)分别为0.12±0.03 mmol/L和1.03±0.31 mmol/L,最大反应速度(V_maxCDNB和V_maxGSH)分别为544.39±37.19 nmol/(min·mg)和715.45±83.68 nmol/(min·mg)。浓度为2×10^-5 mol/L时,槲皮素和辛硫磷对黑胸散白蚁GSTs活性的抑制作用要强于黑翅土白蚁,对黑胸散白蚁GSTs活性的抑制作用分别为62.28％和44.89％,对黑翅土白蚁GSTs活性的抑制作用分别为54.96％和28.36％。高效氯氰菊酯、甲氰菊酯、啶虫脒和单宁酸对黑翅土白蚁GSTs活性的抑制作用要强于黑胸散白蚁,对黑翅土白蚁GSTs活性的抑制作用分别为39.43％,72.07％,52.24％和82.19％;对黑胸散白蚁GSTs活性的抑制作用分别为14.96％,40.23％,39.96％和57.80％。阿维菌素对黑翅土白蚁和黑胸散白蚁GSTs活性的抑制作用没有显著差异,对黑翅土白蚁和黑胸散白蚁GSTs活性的抑制作用分别为76.21％和76.88％。这表明两种白蚁对药剂的敏感性完全不同。实验结果还表明,在3.2×10^-8～2×10^-5 mol/L内,上述植物次生物质和杀虫剂对两种白蚁GSTs活性的抑制率存在明显的剂量-效应关系。     

Organophosphorus insecticides synergize pyrethroids in the resistant strain of cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) from West Africa

Helicoverpa armigera (Hübner) populations from West Africa recently developed resistance to pyrethroid insecticides through enhanced metabolism by mixed-function oxidases. The combination index method was used to study the synergism of pyrethroids by organophosphorus insecticides. Several mixtures of insecticides currently registered to control cotton pest complex in West Africa were tested, including: cypermethrin/ethion, cypermethrin/profenofos, deltamethrin/ triazophos, deltamethrin/chlorpyriphos, cyfluthrin/chlorpyriphos, and betacyfluthrin/chlorpyriphos. In the resistant strain, the organophosphorus insecticides significantly increased the toxicity of pyrethroids suppressing the resistance effect, either by additive or synergistic effects. Significant synergism was shown for the following mixtures: cypermethrin/ethion, deltamethrin/triazophos, and deltamethrin/chlorpyriphos. The use of synergism from these insecticide mixtures should prove to be an additional tool in the overall resistance management strategy because the pyrethroid resistance in H. armigera from West Africa is not yet stable, decreasing between cotton seasons and increasing with treatments. In absence of selection, the susceptibility of H. armigera to insecticides should be restored.     

Plant essential oils synergize various pyrethroid insecticides and antagonize malathion in Aedes aegypti

Pyrethroid resistance is a significant threat to agricultural, urban and public health pest control activities. Because economic incentives for the production of novel active ingredients for the control of public health pests are lacking, this field is particularly affected by the potential failure of pyrethroid‐based insecticides brought about by increasing pyrethroid resistance. As a result, innovative approaches are desperately needed to overcome insecticide resistance, particularly in mosquitoes that transmit deadly and debilitating pathogens. Numerous studies have demonstrated the potential of plant essential oils to enhance the efficacy of pyrethroids. The toxicity of pyrethroids combined with plant oils is significantly greater than the baseline toxicity of either oils or pyrethroids applied alone, which suggests there are synergistic interactions between components of these mixtures. The present study examined the potential of eight plant essential oils applied in one of two concentrations (1% and 5%) to enhance the toxicity of various pyrethroids (permethrin, natural pyrethrins, deltamethrin and β‐cyfluthrin). The various plant essential oils enhanced the pyrethroids to differing degrees. The levels of enhancement provided by combinations of plant essential oils and pyrethroids in comparison with pyrethroids alone were calculated and synergistic outcomes characterized. Numerous plant essential oils significantly synergized a variety of pyrethroids; type I pyrethroids were synergized to a greater degree than type II pyrethroids. Eight plant essential oils significantly enhanced 24‐h mortality rates provided by permethrin and six plant essential oils enhanced 24‐h mortality rates obtained with natural pyrethrins. By contrast, only three plant essential plants significantly enhanced the toxicity of deltamethrin and β‐cyfluthrin. Of the plant essential oils that enhanced the toxicity of these pyrethroids, some produced varying levels of synergism and antagonism. Geranium, patchouli and Texas cedarwood oils produced the highest levels of synergism, displaying co‐toxicity factors of > 100 in some combinations. To assess the levels of enhancement and synergism of other classes of insecticide, malathion was also applied in combination with the plant oils. Significant antagonism was provided by a majority of the plant essential oils applied in combination with this insecticide, which suggests that plant essential oils may act to inhibit the oxidative activation processes within exposed adult mosquitoes.