灰飞虱对几种杀虫剂的抗性

采用稻苗浸渍法测定了灰飞虱对7种常用杀虫剂的抗性。2011年监测了我国江苏、浙江、安徽三省9个灰飞虱种群对噻虫嗪、烯啶虫胺、毒死蜱、吡蚜酮、噻嗪酮、高效氯氰菊酯及氟虫腈的抗性。结果表明:灰飞虱对噻虫嗪都处于敏感阶段(0.6~2.2倍);对烯啶虫胺处于敏感阶段(0.8~3.0倍);对毒死蜱产生了中-高水平抗性(17.5~83.6倍);对吡蚜酮为敏感到低水平抗性(1.9~5.5倍);对噻嗪酮的抗性为高-极高水平(136.4~271.1倍);对高效氯氰菊酯的抗性为低-中等水平(5.2~34.9倍);对氟虫腈为低水平抗性(0.9~8.0倍)。基于灰飞虱对7种药剂的抗性情况,对田间治理灰飞虱合理使用药剂进行了讨论。     

安徽庐江褐飞虱的抗药性监测及不同杀虫剂对其田间防效评价

近年来,褐飞虱田间种群已对多种药剂产生了抗性,为筛选可防控褐飞虱的高效药剂,2020年-2022年采用稻茎浸渍法连续测定了安徽省庐江县褐飞虱种群对三氟苯嘧啶、呋虫胺、烯啶虫胺、吡蚜酮、氟啶虫胺腈等5种药剂的抗性水平,并在庐江县开展了不同药剂对褐飞虱田间防效试验。室内抗性监测结果表明,2020年-2022年褐飞虱种群对吡蚜酮始终处于高水平抗性(抗性倍数104.6~154.4倍),对呋虫胺的抗性从中等水平上升至高水平(抗性倍数77.7~157.2倍),对氟啶虫胺腈、烯啶虫胺处于中等水平抗性(氟啶虫胺腈抗性倍数21.3~64.5倍、烯啶虫胺抗性倍数14.6~22.6倍),对三氟苯嘧啶处于敏感状态。庐江单季稻试验田田间试验结果表明,在推荐高剂量下,20%三氟苯嘧啶WG、10%异唑虫嘧啶SC等介离子杀虫剂对褐飞虱速效性和持效性表现较好,除了药后1 d 20%三氟苯嘧啶WG防效为74.72%外,2种药剂3~14 d的防效都在80%以上;50%烯啶虫胺SG、22%氟啶虫胺腈SC防效次之,药后1 d防效在67.63%~71.61%,药后3 d至7 d防效有所提高,为77.16%~84.13%,而药后14 d防效降为71.52%~75.77%;50%吡蚜酮WG药后1~7 d防效均在约70%,而药后14 d下降为62.12%;20%氟啶虫酰胺SC、20%呋虫胺WG、10%醚菊酯SC速效性和持效性都表现较差,药后1~14 d防治效果都在80%以下。结合室内抗药性监测和田间防治效果,说明三氟苯嘧啶等介离子类杀虫药剂作为新型杀虫剂品种,可与新烟碱类、吡蚜酮及其混剂交替轮换使用,用于抗药性褐飞虱的治理。     

华东4地区灰飞虱对8种杀虫剂的抗性监测

为明确2021—2022年华东4地区灰飞虱田间种群对常用杀虫剂的抗性现状及抗性机理，采用稻苗浸渍法分别测定了江苏仪征、盐城，浙江长兴和安徽庐江4地区灰飞虱田间种群对8种杀虫剂的抗性水平，并测定了3种解毒酶抑制剂增效醚(PBO)、顺丁烯二酸二乙酯(DEM)和磷酸三苯酯(TPP)对噻嗪酮防治灰飞虱的增效作用。结果表明：4个灰飞虱田间种群对噻嗪酮产生了中等至高水平抗性(抗性倍数RR=61.5～148.8)；对毒死蜱产生了中等水平抗性(RR=14.9～28.3)；对烯啶虫胺(RR=0.7～9.9)、噻虫嗪(RR=1.6～8.3)、呋虫胺(RR=2.9～10.0)和氟啶虫胺腈(RR=2.5～8.7)处于敏感至低水平抗性；对吡蚜酮(RR=1.0～5.0)和三氟苯嘧啶(RR=0.5～2.3)均仍处于敏感水平。增效试验结果显示，3种解毒酶抑制剂对噻嗪酮均无显著增效作用，表明3种解毒酶可能不参与灰飞虱对噻嗪酮的抗性。研究结果可为灰飞虱的田间抗性治理提供科学指导。     

褐飞虱抗药性机理及其治理研究进展

褐飞虱是一种重要的农业害虫,其对许多杀虫剂都产生了抗药性。化学药剂的大量不合理使用是导致褐飞虱产生抗药性的主要原因。褐飞虱的抗药性机理主要包括代谢抗性和靶标抗性。本文对褐飞虱的抗药性机理进行了综述,并对该虫的抗性治理进行了探讨。褐飞虱的抗性治理策略应包括抗性监测、使用新型药剂、合理使用杀虫剂及抗虫品种等。     

宁夏地区烟粉虱对5种常用杀虫剂的抗药性

采用浸叶法分别测定了宁夏8个地区烟粉虱成虫田间种群对4类5种杀虫剂的抗性。结果表明,供试烟粉虱种群对高效氯氰菊酯已产生了中等至极高水平抗性,抗性倍数为33.31~227.98倍;对烯啶虫胺产生了中等至高水平抗性,抗性倍数为12.14~69.33倍;对毒死蜱和吡虫啉产生了低至中等水平抗性,抗性倍数分别为7.63~38.85倍和6.05~22.43倍,个别地区种群对吡虫啉尚处于敏感水平;对阿维菌素处于敏感性降低至中等水平抗性,抗性倍数为4.54~13.22倍。烟粉虱对5种杀虫剂的抗性有明显的区域性,抗性最为普遍且严重的地区为贺兰新平和吴忠,其次为贺兰产业园、石嘴山大武口、中卫和永宁,而西夏区军马场、固原烟粉虱种群的抗性则相对较低。对银川3地烟粉虱抗药性监测结果表明,在5种杀虫剂中,其对高效氯氰菊酯的抗性发展最为迅速,其次为烯啶虫胺,对阿维菌素和吡虫啉的抗性发展相对较慢,而西夏区军马场和贺兰产业园种群对毒死蜱敏感性有所恢复。     

荆州地区褐飞虱对吡虫啉、噻嗪酮的抗药性测定

为了解褐飞虱田间种群的抗性水平,笔者采用稻茎浸渍法测定了湖北荆州地区褐飞虱田间种群对吡虫啉和噻嗪酮的抗药性.结果表明,荆州地区褐飞虱田间种群对吡虫啉的抗性倍数为57.22～177.00,达到高水平至极高水平抗性;对噻嗪酮的抗性倍数为5.70～16.81,为低水平至中等水平抗性.     

中国水稻主产区褐飞虱对3种杀虫剂的抗性监测

2006-2009年,用稻茎浸渍法连续监测了广西南宁市、广东阳江市、湖南东安县、福建福清市、江西上高县、湖北孝感市、浙江金华市、江苏通州市和安徽和县共9个地区褐飞虱种群对吡虫啉、噻嗪酮和氟虫腈的抗性变化。结果表明:褐飞虱种群对吡虫啉的抗性仍处于高水平至极高水平抗性阶段(105.5~459.7倍),但2009年监测到东安、孝感、上高种群对吡虫啉的抗性已有下降趋势;褐飞虱种群对氟虫腈的抗性有增长趋势,2006到2009年褐飞虱种群对氟虫腈由敏感至低水平抗性(<6.9倍)发展到了中水平至高水平抗性(13.5~43.3倍);由于2005年吡虫啉在高抗地区的禁用,褐飞虱种群对噻嗪酮的抗性上升速度加快,2009年已处于低水平至中水平抗性阶段(7.0~14.4倍)。这表明在吡虫啉、氟虫腈被禁用后,大面积单一使用噻嗪酮进行防治,褐飞虱对噻嗪酮的抗性有可能加速发展。     

新型杀虫剂对新疆抗药性棉蚜的田间防效

测定新疆棉区沙湾的棉蚜种群对常用杀虫剂吡虫啉、丁硫克百威、溴氰菊酯、氟啶虫酰胺和氟啶虫胺腈的抗性水平,并在当地棉田开展了新型杀虫剂防治棉蚜试验。室内抗药性监测结果表明,2021—2022年新疆沙湾棉蚜种群对溴氰菊酯、吡虫啉处于高水平抗性（抗性倍数分别大于4 500倍、大于3 500倍）,对丁硫克百威处于中等至高水平抗性（抗性倍数96～237倍）,对氟啶虫胺腈处于中等水平抗性（抗性倍数17～27倍）,对氟啶虫酰胺处于低至中等水平抗性（抗性倍数7.8～15.0倍）。田间试验结果表明,50 g/L双丙环虫酯可分散液剂、20%氟啶虫酰胺悬浮剂喷施处理第3天对棉蚜的防效为86.0%、83.4%,第7天防效为93.1%、96.0%,第14天防效为92.6%、92.0%,明显优于其他4种供试药剂,表现出较好的速效性和持效性。由此得出新型杀虫剂品种双丙环虫酯、氟啶虫酰胺可作为轮换或替代药剂用于新疆抗药性棉蚜的治理。     

河南省灰飞虱田间种群对12种杀虫剂的抗性现状分析

为明确河南省不同地区灰飞虱田间种群对12种常用杀虫剂的抗性现状,于2020—2021年,采用稻苗浸渍法分别测定了河南新乡、濮阳、开封、驻马店及信阳等地区灰飞虱田间种群对12种杀虫剂的抗性水平。结果表明:河南省灰飞虱田间种群对噻嗪酮产生了中等水平抗性,抗性倍数 (RR) =14.9~91.1;对吡蚜酮 (RR=6.91~16.7) 和毒死蜱 (RR=8.48~70.0) 产生了低至中等水平抗性;对三唑磷 (RR=1.29~11.1) 处于敏感至中等水平抗性;对噻虫嗪 (RR=0.95~5.19) 和高效氯氟氰菊酯 (RR=3.31~7.24) 处于敏感至低水平抗性;对吡虫啉 (RR=0.89~3.92)、啶虫脒 (RR=1.11~2.33)、烯啶虫胺 (RR=0.16~0.64)、呋虫胺 (RR=1.87~3.86)、异丙威 (RR=0.47~1.37) 和氟啶虫酰胺 (RR=1.63~4.33) 均仍处于敏感水平。研究结果可为河南省田间灰飞虱的可持续性防控以及杀虫剂的科学合理使用提供参考。     

草地贪夜蛾对甲氨基阿维菌素苯甲酸盐和虱螨脲的抗性风险评估

甲氨基阿维菌素苯甲酸盐(甲维盐)和虱螨脲是目前生产上防治草地贪夜蛾的主要杀虫剂,为评估其抗性风险,以福建省草地贪夜蛾田间种群为研究对象,在实验室抗性汰选品系选育基础上,采用数量遗传学域性状分析法并结合交互抗性测定,进行草地贪夜蛾对上述两种杀虫剂的抗性风险评估。结果表明：非连续汰选11代和10代后,草地贪夜蛾对甲维盐(F₁₁)和虱螨脲(F₁₀)的抗性倍数分别达30.57倍和11.35倍;抗性现实遗传力分别为0.403和0.555,且前半段筛选的抗性遗传力都远大于后半段;药剂在室内对草地贪夜蛾致死率为50%～90%时,对甲维盐和虱螨脲抗性倍数上升10倍需要汰选8～15代和6～12代。交互抗性测定显示,甲维盐汰选品系对氯虫苯甲酰胺、虱螨脲、虫螨腈无交互抗性,对茚虫威和乙基多杀菌素存在一定交互抗性。虱螨脲汰选品系对氯虫苯甲酰胺、甲维盐、茚虫威、虫螨腈和乙基多杀菌素均无交互抗性。结果表明：草地贪夜蛾对甲维盐和虱螨脲存在快速产生抗性的风险,但可通过与无交互抗性药剂轮用来延缓抗性发展。     

粘质沙雷氏菌S-JS1与5种杀虫剂对灰飞虱的联合作用及该菌对灰飞虱相关酶活性的影响

为明确粘质沙雷氏菌Serratia marcescens S-JS1与杀虫剂对灰飞虱的联合作用,以及S-JS1对灰飞虱解毒酶和保护酶活性的影响,以灰飞虱3龄若虫为对象,采用喷雾法比较了S-JS1与5种杀虫剂 (螺虫乙酯、噻虫嗪、吡虫啉、啶虫脒和毒死蜱) 单用,以及菌、药混用对灰飞虱的杀虫活性,测定了灰飞虱取食经S-JS1处理的水稻后,虫体内羧酸酯酶 (CarE)、谷胱甘肽-S-转移酶 (GSTs)、过氧化物酶 (POD) 和超氧化物歧化酶 (SOD) 的活性变化。结果表明:粘质沙雷氏菌S-JS1分别与不同浓度杀虫剂混用,均可提高杀虫剂对灰飞虱的致死率。其中,109 cfu/mL的S-JS1与1.25 mg/L的噻虫嗪混用处理3 d,或与25 mg/L的螺虫乙酯混用处理5 d,灰飞虱的死亡率分别为65.58%和76.27%,均显著高于同浓度杀虫剂单用的处理 (噻虫嗪单用时致死率为44.24%,螺虫乙酯为49.22%),表现为增效作用 (χ2 > 3.84,实测死亡率 – 预期死亡率 > 0);其他各混用处理均为相加作用 (χ2 < 3.84)。灰飞虱取食经粘质沙雷氏菌处理的水稻苗后12和24 h,其CarE活性与对照组间无显著性差异,GSTs活性呈先降低后升高趋势,POD和SOD活性均低于对照组。研究表明,粘质沙雷氏菌S-JS1可能降低了灰飞虱对杀虫剂的抵抗力。本研究可为探索昆虫病原细菌与杀虫剂间的联合应用提供参考,为灰飞虱的有效防治提供新思路。     

华北棉区棉铃虫对三种杀虫剂的抗性监测

为明确华北棉区棉铃虫Helicoverpa armigera田间种群对3种常用杀虫剂的抗性,于2014—2015年和2018—2019年分别采集河南、河北、山东和山西4个省的棉铃虫田间种群,采用浸叶法于室内测定棉铃虫对辛硫磷、三氟氯氰菊酯和甲维盐的抗性水平。结果表明,各监测点棉铃虫对辛硫磷处于中等水平抗性,在2014—2015年和2018—2019年的抗性倍数分别为13.0~58.5倍和21.1~55.3倍,棉铃虫对辛硫磷的抗性发展相对缓慢;各监测点棉铃虫种群对三氟氯氰菊酯已产生中等至高水平抗性,并呈现逐年上升的趋势,其中河北沧县、河南安阳、山西盐湖种群的抗性倍数由2014年的61.0倍、22.5倍和24.0倍上升至2019年的91.1倍、44.7倍和61.3倍,山东夏津种群的抗性最高,2019年抗性倍数达到216.3倍;棉铃虫种群对甲维盐表现为低至中等水平抗性,河北沧县、河南安阳、山西盐湖和山东夏津种群的抗性倍数分别为8.2~40.4倍、5.8~16.6倍、5.5~23.4倍和11.0~36.6倍。表明4个监测地区的棉铃虫田间种群对3种杀虫剂已经产生了不同程度的抗性,建议减少这3种杀虫剂的使用频次,并注意与其他杀虫剂交替轮换使用,以延缓棉铃虫抗药性的发展。     

Dominance variation across six herbicides of the Arabidopsis thaliana csr1-1 and csr1-2 resistance alleles

Dominance of a resistance trait can be defined as a measure of the relative position of the phenotype of the heterozygote RS compared with the phenotype of the two corresponding homozygotes, SS and RR. This parameter has been shown to have primary importance in the dynamics of pesticide resistance evolution. Literature on insecticide resistance suggests that dominance levels in the presence of insecticide vary greatly from completely recessive to completely dominant. With insecticides, both the chemical applied and the dosages used have been demonstrated to affect the dominance. By contrast, almost all herbicide resistances have been found to be inherited as partially to totally dominant traits. This discrepancy between weeds and insects may partly result from the methodologies applied to measure the dominance, ie a single dose for herbicide versus several doses for insecticide. Using two well-known resistances (csr1-1 and csr1-2) to acetolactate synthase (ALS) inhibitors in Arabidopsis thaliana (L) Heynh (mouse-ear cress), we used several herbicide doses to determine the dominance level to six ALS-inhibiting herbicides. The dominance level in the presence of herbicide varied from completely dominant to completely recessive, depending on the resistance allele and the herbicide tested. The dominance of the csr1-1 and csr1-2 resistance alleles ranged from 0 (completely recessive) to 1.1 (dominant) and from 0 to 0.3 (partially dominant), respectively. The recessivity of some resistance alleles in the presence of herbicide could lead to the development of improved resistance management in order to delay or avoid herbicide resistance evolution, especially in the control of outcrossing weed species.     

陕西关中地区小麦田禾谷缢管蚜对7种杀虫剂的抗性监测

为明确陕西关中地区麦蚜田间种群对杀虫剂的抗药性现状,采用浸叶法测定了兴平、礼泉、凤翔、岐山、扶风地区麦田禾谷缢管蚜种群对高效氯氰菊酯、溴氰菊酯、吡虫啉、异丙威、毒死蜱、阿维菌素、氟啶虫胺腈等7种杀虫剂的抗性水平。结果表明,禾谷缢管蚜对高效氯氰菊酯的抗性水平最高,其中凤翔种群对高效氯氰菊酯达到高水平抗性(抗性倍数为72.5),岐山和扶风种群对该药产生中等水平抗性(抗性倍数分别为31.4、29.9);5个地区的禾谷缢管蚜对溴氰菊酯、吡虫啉、毒死蜱、异丙威和阿维菌素的抗性水平较低,表现为敏感、敏感性下降或者低抗性;5个地区的试虫对氟啶虫胺腈均表现为敏感。分析认为,高效氯氰菊酯不适合用于关中地区禾谷缢管蚜防治,氟啶虫胺腈作为一种新型杀虫剂,可以在该虫防治中推广使用,吡虫啉、阿维菌素等其他几种杀虫剂可以在禾谷缢管蚜的防治中交替使用。     

Assessment of insecticide resistance in eggs and neonate larvae of Cydia pomonella (Lepidoptera: Tortricidae)

Spanish Cydia pomonella (L.) field populations have developed resistance to several insecticide groups. Diagnostic concentrations were established as the LC₉₀ calculated on a susceptible strain (S_Spain) for five and seven insecticides and tested on eggs and neonate larvae field populations, respectively. The three most relevant enzymatic detoxification systems (mixed-function oxidases (MFO), glutathione S-tranferases (GST) and esterases (EST)) were studied for neonate larvae.In eggs, 96% of the field populations showed a significantly lower efficacy when compared with the susceptible strain (S_Spain) and the most effective insecticides were fenoxycarb and thiacloprid. In neonate larvae, a significant loss of susceptibility to the insecticides was detected. Flufenoxuron, azinphos-methyl and phosmet showed the lowest efficacy, while lambda-cyhalothrin, alpha-cypermethrin and chlorpyrifos-ethyl showed the highest. Biochemical assays showed that the most important enzymatic system involved in insecticide detoxification was MFO, with highest enzymatic activity ratios (5.1-16.6 for neonates from nine field populations). An enhanced GST and EST activities was detected in one field population, with enzymatic activity ratios of threefold and fivefold for GST and EST, respectively, when compared with the susceptible strain. The insecticide bioassays showed that the LC₉₀ used were effective as diagnostic concentrations. Measures of MFO activity alongside bioassays with insecticide diagnostic concentrations could be used as tools for monitoring insecticide resistance in neonate larvae of C. pomonella.     

中国陕晋两省部分地区粘虫田间种群的抗药性

采用浸叶法在室内测定了采自中国陕西省（陕）长安区、华阴县、三原县、兴平市和山西省（晋）太谷县5个地区的粘虫田间种群对6种常用杀虫剂的抗药性。结果表明:5个地区粘虫种群对甲氨基阿维菌素苯甲酸盐（以下简称甲维盐）均表现为敏感,抗性倍数（RR）为0.6~1.6;对氯虫苯甲酰胺和高效氯氰菊酯为敏感至低水平抗性,RR为0~6.2;对高效氯氟氰菊酯和毒死蜱为敏感至中等水平抗性,RR为0.1~32.8;对辛硫磷,除陕西省三原县种群表现为敏感外,其他4个种群均表现为中等至高水平抗性,RR为19.4~70.1。药剂毒力相关性分析表明,毒死蜱和甲维盐之间存在显著相关性,氯虫苯甲酰胺与甲维盐、毒死蜱及辛硫磷之间不存在明显的相关性。因此陕晋两省上述地区的粘虫防治推荐选用甲维盐、氯虫苯甲酰胺和高效氯氰菊酯,同时应注意将氯虫苯甲酰胺和甲维盐、毒死蜱等轮换使用,以延缓抗药性的产生和发展。     

4种杀虫剂对玉米3种害虫的毒力及种子处理防治效果评价

为评价4种杀虫剂在玉米田防治灰飞虱Laodelphax striatellus、禾蓟马Frankliniella tenuicornis和玉米蚜Rhopalosiphum maidis的应用前景,采用浸苗法测定了其对3种害虫的毒力,并通过种子处理筛选对3种害虫田间防效较高的药剂。结果表明,噻虫嗪、呋虫胺和吡虫啉对灰飞虱、禾蓟马和玉米蚜具有较高毒力,LC50分别为0.14～1.10、4.24～31.01 mg/L和0.80～7.49 mg/L,氟啶虫酰胺的毒力最低,对3种害虫的LC50分别为84. 55、222.72 mg/L和44.81 mg/L。采用种子处理的方式施药后,各药剂处理组玉米出苗率与对照组无显著差异,安全性较高;播种后30 d,20%氟啶虫酰胺种子处理悬浮剂对灰飞虱、禾蓟马的防效均在75%以上,播种后40 d,70%噻虫嗪种子处理可分散粉剂对灰飞虱防效最高,其次为20%氟啶虫酰胺种子处理悬浮剂、8%呋虫胺悬浮种衣剂和600 g/L吡虫啉悬浮种衣剂;播种后50 d(玉米抽雄期)调查,20%氟啶虫酰胺种子处理悬浮剂对玉米蚜防治效果可达92.1%,表现出较高的防治效果,噻虫嗪、呋虫胺、吡虫啉防治效果略低,但均在70%以上,能有效防治玉米蚜的为害。综上,氟啶虫酰胺、噻虫嗪、呋虫胺和吡虫啉均适合用于防治玉米田灰飞虱、禾蓟马和玉米蚜3种害虫。     

Cytochrome P450 monooxygenase-mediated permethrin resistance confers limited and larval specific cross-resistance in the southern house mosquito, Culex pipiens quinquefasciatus

The cytochrome P450-dependent monooxygenases (P450s) are an important enzymatic system that metabolizes xenobiotics (e.g., pesticides), as well as endogenous compounds (e.g., hormones). P450-mediated metabolism can result in detoxification of insecticides such as pyrethroids, or can be involved in the bioactivation and detoxification of insecticides such as organophosphates. We isolated (from the JPAL strain) a permethrin resistant strain (ISOP450) of Culex pipiens quinquefasciatus, having 1300-fold permethrin resistance using standard backcrossing procedures. ISOP450 is highly related to the susceptible lab strain (SLAB) and the high resistance to permethrin is due solely to P450-mediated detoxification. This is the first time in mosquitoes that P450 monooxygenase involvement in pyrethroid resistance has been isolated and studied without the confounding effects of kdr. Resistance in ISOP450 is incompletely dominant (D = +0.3), autosomally linked, and monofactorally inherited. It is expressed in the larvae, but not in adults. Cross-resistance to pyrethroids lacking a 3-phenoxybenzyl moiety (tetramethrin, fenfluthrin, bioallethrin, and bifenthrin) ranged from 1.5- to 12-fold. ISOP450 had only limited (6.6- and 11-fold) cross-resistance to 3-phenoxybenzyl pyrethroids with an α-cyano group (cypermethrin and deltamethrin, respectively). Examination of cross-resistance patterns to organophosphate insecticides in ISOP450 showed an 8-fold resistance to fenitrothion, while low, but significant, levels of negative cross-resistance were found for malathion (RR = 0.84), temephos (RR = 0.73), and methyl-parathion (RR = 0.55). The importance and uniqueness of this P450 mechanism in insecticide resistance is discussed.     

Development of a bioassay system for monitoring susceptibility in Thrips tabaci

A system is described for collecting adult and larva of Thrips tabaci from onion foliage into insecticide-treated vials to evaluate susceptibility to insecticides. The thrips insecticide bioassay system (TIBS) allows one to treat vials and store them for 3 weeks before thrips are collected. Depending on the population density in the field, collection of the insects for the test required from 3-6 h for one person. Assays are read after 24h. This system was used in 1997 and 1998 in commercial onion fields in Honduras and Nicaragua, and TIBS was sensitive enough to detect differences to the insecticides tested, to thrips life stages and to different generations within an onion-growing season. Data collected suggest that there were not serious problems with thrips insecticide resistance, with the possible exception of cypermethrin in Nicaragua which had a resistance ratio (RR) value of 26.9 for adult thrips. The largest RR values were observed at the end of the growing season, and this may be caused by the season-long selection by insecticide sprays. The mortality of adults and larvae followed the same general pattern, but the ratio between larvae and adults differed for each chemical group.