Resistance in the mealybug Phenacoccus solenopsis Tinsley (Homoptera: Pseudococcidae) in Pakistan to selected organophosphate and pyrethroid insecticides

The mealybug Phenacoccus solenopsis is a destructive pest of cotton with the potential to develop resistance to most chemical classes of insecticides. Six populations of P. solenopsis from cotton crops at six different locations in Pakistan were evaluated for resistance to selected organophosphate and pyrethroid insecticides. Resistance ratios (RRs) at LC₅₀ were in the range of 2.7–13.3 fold for chlorpyrifos, 11.6–30.2 fold for profenofos and for the three pyrethroids tested were 10.6–46.4 for bifenthrin, 5.8–25.2 for deltamethrin and 4.1–25.0 for lambda-cyhalothrin. This is the first report of resistance to organophosphate and pyrethroid insecticides in Pakistani populations of P. solenopsis. Regular insecticide resistance monitoring programs are needed to prevent field control failures. Moreover, integrated approaches including the judicious use of insecticides and rotation of insecticides with different modes of action are needed to delay the development of insecticide resistance in P. solenopsis.     

防治水稻二化螟的高毒农药替代药剂的室内筛选

为了筛选防治水稻二化螟的高毒农药替代药剂,采用点滴法测定了7类32种药剂对不同水稻生态区二化螟种群的室内毒力。基于这些毒力数据,推荐对二化螟毒力较高的7种新型农药（氟虫腈、阿维菌素、甲氨基阿维菌素苯甲酸盐、虫酰肼、呋喃虫酰肼、氟铃脲和氟啶脲）和一些中低毒性的有机磷品种（如辛硫磷、喹硫磷、毒死蜱和哒嗪硫磷）作为大田药效试验的候选替代药剂。评估了田间二化螟对10种拟除虫菊酯类杀虫剂的敏感性,发现7种对鱼高毒的拟除虫菊酯类杀虫剂（高效氟氯氰菊酯、λ 高效氯氟氰菊酯、溴氰菊酯、高效氯氰菊酯、顺式氯氰菊酯、甲氰菊酯和S 氰戊菊酯）对二化螟的毒力高于大多数有机磷类农药。虽然我国禁止上述菊酯类杀虫剂在水稻上使用,但是浙江瑞安田间种群（RA05）已对高效氟氯氰菊酯、溴氰菊酯、高效氯氰菊酯和λ 高效氯氟氰菊酯等产生高水平抗性（抗性倍数分别为166.7、51.9、41.3和36.8倍）。对鱼低毒的3种菊酯类农药（乙氰菊酯、醚菊酯和氟硅菊酯）对抗性二化螟（RA05）的毒力高于三唑磷。因此,可考虑将这些对鱼低毒的菊酯类农药作为防治水稻二化螟的高毒农药的替代药剂和抗性治理的轮换品种。     

Resistance of beet armyworm Spodoptera exigua (Lepidoptera: Noctuidae) to endosulfan,organophosphorus and pyrethroid insecticides in Pakistan

Field populations of beet armyworm, Spodoptera exigua (Lepidoptera: Noctuidae), from Pakistan were assessed for their resistance to the chlorinated hydrocarbon endosulfan, the organophosphates chlorpyrifos and quinalphos, and the pyrethroids cypermethrin, deltamethrin, bifenthrin and fenpropathrin. Using a leaf-dip bioassay, resistance to endosulfan was high during 1998–2000 but declined to very low, to low levels during 2001–2007, following a reduced use of the insecticide. Organophosphates and pyrethroids were consistently used over the past three decades, and the resistance had been increasing to these insecticide classes. Generally, the resistance to chlorpyrifos and pyrethroids remained low from 1998 to 2002–2003, but resistance increased to moderate to high levels from 2003–2004 to 2006–2007. For deltamethrin, resistance was very high during 2004–2007. Quinalphos resistance remained low during 1998–2006. Correlation analysis of LC₅₀ and LC₉₀ values showed a positive correlation between organophosphates and pyrethroids, but no correlation between endosulfan and organophosphates or pyrethroids tested herein. These results suggest that the conventional chemistries should be replaced with new chemistries for the successful management of S. exigua.     

Development of resistance to insecticides in the invasive mealybug Phenacoccus solenopsis (Hemiptera: Pseudococcidae) in Pakistan

The mealybug Phenacoccus solenopsis has been a serious pest of cotton, vegetables, ornamentals and other plants since its invasion into Pakistan in 2005. Its susceptibility to commonly-used insecticides was monitored during 2005–2013 by a nymphal dip bioassay. Initially, P. solenopsis was found susceptible to a range of insecticide classes. Lethal concentration values were particularly low for organophosphates and pyrethroids. After a year of its exposure to insecticides, P. solenopsis developed moderate to high levels of resistance to pyrethroids. After two years, resistance to organophosphates methidathion and chlorpyrifos also rose to moderate to high levels. After five years of use, resistance to pyrethroids, organophosphates, neonicotinoids, endosulfan, carbosulfan, and thiocyclam was generally high to very high. Acetamiprid resistance was slow to develop, as it reached moderate level of resistance after seven years of its extensive applications. Insecticide resistance in P. solenopsis could have been managed in Pakistan if the effective and diverse insecticides were used in rotation, along with other integrated pest management tactics, at the initial stages of resistance development.     

Efficacy of entomopathogenic nematodes (Nematoda: Rhabditida) and insecticide mixtures to control Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae) in corn crops

The main insect pest in Brazilian corn is fall armyworm, Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae). Entomopathogenic nematodes (EPNs) can be used to control this pest, and can be applied together with various insecticides. Thus, the objective of this work was to evaluate the efficacy of mixtures of EPNs and insecticides to control S. frugiperda in corn crops. In laboratory bioassays three species of EPNs were tested (Heterorhabditis indica, Steinernema carpocapsae and Steinernema glaseri) together with 18 registered insecticides to control S. frugiperda in corn. Efficacy of association between insecticides and EPNs on S. frugiperda larvae was evaluated against the insect's third instar, 2 and 4 days after applications in laboratory. Experiments in the field were performed in two consecutive years, with located application of H. indica and S. carpocapsae (250 IJs/cm²) mixed with chlorpyrifos (0.3 L/ha) and lufenuron (0.15 L/ha) on the corn husk. In laboratory, after two days exposure the interaction between chlorpyrifos and H. indica was synergistic, while interaction with cypermethrin, spinosad, methoxyfenozide and deltamethrin + triazofos was additive, as was interaction between lufenuron, chlorpyrifos and cypermethrin with S. carpocapsae. In contrast, the interaction between chlorpyrifos (Vexter™ and Lorsban™) and lufenuron with S. glaseri was synergistic. In the field, the best treatment was the mixture of H. indica with lufenuron (0.15 L/ha), with 62.5% and 57.5% larval mortality in the two evaluation years in the field, respectively.     

Stability,cross-resistance and fitness costs of resistance to emamectin benzoate in a re-selected field population of the beet armyworm,Spodoptera exigua (Lepidoptera: Noctuidae)

Spodoptera exigua (Hübner) has a worldwide distribution with a high capacity for damaging a wide range of food, forage and fiber crops. It has been reported extensively from all over the world that populations of this pest species have developed field resistance against many insecticides. The objectives of this study were to determine whether an emamectin benzoate resistant field population of S. exigua re-selected with emamectin benzoate in the laboratory (Ema-SEL) showed cross-resistance to other insecticides, whether resistance was stable under laboratory conditions, and whether there were fitness costs associated with emamectin benzoate resistance. Bioassays at G₁ for the field population, gave resistance ratios (RRs) of 220, 149 and 38-fold for emamectin benzoate, spinosad and lufenuron, respectively, compared with a susceptible laboratory population (Lab-PK). Resistance ratios were increased by 526-fold and 6-fold compared with Lab-PK and the unselected field population (Ema-UNSEL, G₆), respectively after selection with emamectin benzoate (Ema-SEL) for five generations (G₆). Selection with emamectin benzoate had no apparent effect on susceptibility of Ema-SEL to spinosad and lufenuron, instead toxicity to the latter insecticides reduced, suggesting there was no cross-resistance between these compounds. Analysis of various life history traits suggested that the Ema-SEL population had a lower overall fitness (0.38) compared with the Lab-PK (1.0). Lack of cross-resistance and the apparent instability of resistance to emamectin benzoate suggest that spinosad and lufenuron are suitable alternatives for use with emamectin benzoate in resistance management. In addition, the high relative fitness costs observed suggests that emamectin benzoate-resistant insects are at a considerable disadvantage to susceptible populations in the absence of selection pressure although this remains to be tested under field conditions.     

Insecticide resistance in Brazilian populations of the cotton leaf worm, Alabama argillacea

The cotton leaf worm, Alabama argillacea, is a key cotton pest in Brazil and is managed with repeated insecticide applications. Reports of insecticide control failures have recently increased, particularly with pyrethroids. The present work assessed the resistance status of A. argillacea to a number of different insecticides currently used in cotton crops. Bioassays were conducted to estimate the response of 2nd-instar A. argillacea populations to deltamethrin, chlorpyrifos, endosulfan, abamectin and spinosad. A leaf dip bioassay with diluted insecticide formulations was performed in the laboratory with five to nine populations depending on the insecticide. LC₅₀ values were estimated by probit analysis after correction for control mortality data and used to calculate the resistance ratios (RR). All assessed populations exhibited varied and significant levels of resistance to all insecticides tested, but only moderate levels of resistance to deltamethrin were observed (RR = 52.3). The LC₅₀ values for deltamethrin were higher than 30 mg/l for most populations, and above the field rate (12.5 mg/l). This suggests that the frequency of resistant individuals in these populations was likely above the critical frequency. There was low to moderate resistance to abamectin, chlorpyrifos, endosulfan and spinosad formulations (the highest RRs observed were 4.2, 8.4, 11.1 and 23.5, respectively). Despite the moderate levels of resistance to pyrethroids in A. argillacea, overall results indicate the presence of low to moderate resistance of A. argillacea to insecticides currently used against cotton pests in Brazil.     

防治稻纵卷叶螟高毒农药替代药剂的室内筛选

 为筛选高毒农药替代药剂,采用Potter喷雾法测定了8类29种杀虫剂对广西南宁和江苏南京稻纵卷叶螟3龄幼虫的室内毒力。这8类杀虫剂的毒力顺序为：抗生素类杀虫剂≥苯基吡唑类杀虫剂≥噁二嗪类杀虫剂≥昆虫生长调节剂类杀虫剂≥有机磷酸酯类杀虫剂、拟除虫菊酯类杀虫剂≥有机氯类杀虫剂≥沙蚕毒素类杀虫剂。甲氨基阿维菌素苯甲酸盐（甲维盐）对两地区稻纵卷叶螟3龄幼虫的触杀毒力最高,其LC50值介于0.2~0.8 mg/L;氟虫腈、茚虫威、呋喃虫酰肼、丁烯氟虫腈、虫酰肼、氟啶脲和氟铃脲的LC50值介于1.8~53 mg/L。推荐对稻纵卷叶螟毒力最高的10种新型杀虫剂（甲维盐、依维菌素、阿维菌素、氟虫腈、茚虫威、呋喃虫酰肼、丁烯氟虫腈、虫酰肼、氟啶脲、氟铃脲）和一些有机磷杀虫剂（喹硫磷、辛硫磷、丙溴磷、毒死蜱、哒嗪硫磷）作为高毒农药替代的候选药剂进行大田药效试验。此外,还讨论了稻纵卷叶螟的药剂防治措施。     

多种药剂对螺旋粉虱不同虫态的毒力测定

采用Potter喷雾法,测定30种杀虫剂对螺旋粉虱成虫与15种杀虫剂对螺旋粉虱若虫的毒力。结果表明:杀扑磷、毒死蜱、辛硫磷、溴氰菊酯、马拉硫磷等对成虫、若虫均具有较高活性。对成虫杀扑磷毒力最强,其LC50值为0.9123mg/L,毒死蜱、辛硫磷、马拉硫磷、顺式氯氰菊酯、溴氰菊酯、敌敌畏及丙溴磷对成虫毒力均较高,其LC50值分别为1.571 4、1.673 1、2.248 2、2.5570、3.039 1、3.186 8、4.1895 mg/L。对若虫溴氰菊酯毒力最强,其LC50值为8.5276mg/L,杀扑磷、毒死蜱、高效氯氟氰菊酯、高效氯氰菊酯对若虫同样具有较高毒力,其LC50值分别为11.486 5、12.9503、12.973 8、13.703 6 mg/L。另通过不同龄期若虫对毒死蜱等8种杀虫剂的敏感性测定,发现1~4龄若虫对杀虫剂的敏感性随虫龄增加而降低,1龄若虫最敏感,2龄和3龄若虫的敏感性相当,4龄若虫敏感性最低。     

Compatibility of entomopathogenic nematodes (Nematoda: Rhabditida) with registered insecticides for Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae) under laboratory conditions

The fall armyworm, Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae) is considered the main key pest of corn crops in Brazil. Entomopathogenic nematodes (EPNs) may be used to control this pest, applied together with other different entomopathogen agents or phytosanity products in the spraying mixture. Thus, the objective of work was to evaluate the compatibility of EPNs with different insecticides used of S. frugiperda control in laboratory conditions. Three species of EPNs (Heterorhabditis indica, Steinernema carpocapsae and Steinernema glaseri) and 18 insecticides registered to control of S. frugiperda in corn crops were tested. Compatibility of the insecticides with EPNs was evaluated by observing mortality and infectivity of infecting juveniles (IJs) 48 h after immersion in solution of the insecticide formulations. Among all insecticides tested, Lorsban™ (chlorpyrifos), Decis™ (deltamethrin), Match™ (lufenuron), Deltaphos™ (deltramethrin + triazophos), Dimilin™ (diflubenzuron), Stallion™ (gamacyhalothrin), Karate Zeon™ (lambdacyhalothrin) Tracer™ (spinosad), Vexter™ (chlorpyrifos), Galgotrin™ (cypermethrin), Certero™ (triflumuron), and Talcord™ (permethrin) were compatible (class 1) with the three nematode species tested under laboratory conditions.     

Selection,mechanism, cross resistance and stability of spinosad resistance in Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae)

Spodoptera litura is one of the most destructive pests in Pakistan and in many other regions of the world. A field collected population of S. litura was selected with spinosad for eleven generations under controlled laboratory conditions to study the cross resistance, mechanism and stability of spinosad resistance in S. litura. The resistance to spinosad in S. litura increased 3921-fold (after eleven generations of selection with spinosad) as compared to a susceptible population of S. litura. No cross resistance between spinosad and emamectin benzoate, methoxyfenozide, fipronil, indoxacarb, profenofos, lufenuron or deltamethrin was found in the spinosad-selected population of S. litura. To find the possible mechanism of spinosad resistance in S. litura two synergists, Piperonyl butoxide (PBO), S, S, S-tributyl phosphorotrithioate (DEF) were tested on the susceptible and resistant strains and on the un-selected field population. The values of the synergism ratios of PBO and DEF were 2.33 and 1.06 for the spinosad-selected strain, 1.36 and 1.06 for the un-selected field population and 1.14 and 1.00 for the susceptible strain, respectively. As high PBO ratio indicates the role of microsomal O-demethylase in causing spinosad resistance in S. litura. The spinosad-resistant and field populations of S. litura were reared without any selection pressure from the 12th to the 16th generation (G₁₂–G₁₆). The spinosad resistance decreased from 3921 to 678-fold in the spinosad-resistant population and from 31.1 to 15.1-fold in the un-selected population of S. litura as compared to the susceptible strain. Spinosad resistance in S. litura has a high reversion rate (−0.15) which indicates that spinosad resistance in S. litura is unstable and can be easily managed by switching off the selection pressure for a few generations or alternating with insecticides having different modes of action.     

Field resistance of Spodoptera litura (Fab.) to conventional insecticides in India

The present study was carried out to evaluate conventional insecticide resistance in populations of Spodoptera litura (Fab.) from seven different soybean-growing districts (Dharwad. Belgaum, Pune, Parbani, Adilabad, Hyderabad and Indore) of India. Experimental results revealed among the three chemical insecticides bioassayed, quinolphos 25 EC registered the highest LC₅₀ value (29.7 mg a.i./L) followed by chlorpyrifos 20 EC (18.3 mg a.i./L) while the lowest LC₅₀ value was found for lambda-cyhalothrin 5 EC (1.3 mg a.i./L) in a susceptible population of S. litura larvae. Evaluation of the seven different populations of S. litura from India showed that populations from Adilabad and Pune exhibited elevated LC₅₀ values for chlorpyrifos [(1622.0 mg a.i./L) and (1137.0 mg a.i./L)], quinolphos [(1892.0 mg a.i./L) and (1744.0 mg a.i./L)] and lambda-cyhalothrin [(56.4 mg a.i./L) and (41.6 mg a.i./L)], respectively. Seven different S. litura populations collected varied in their resistance ratio (RR) for three conventional insecticides used in this study. For chlorpyrifos RR values ranged from 3 to 88 fold, for quinolphos RR values ranged from 3 to 63 fold and for lambda-cyhalothrin RR values ranged from 2 to 42 fold in the seven different S. litura populations compared to the susceptible population. Based on the raised LC₅₀ values, the resistance is quite concerning for organophosphates (chlorpyrifos and quinolphos). The present study is a warning bell suggesting the cautious use of organophosphates and lambda-cyhalothrin in soybean.     

Monitoring of insecticide resistance in Diaphorina citri Kuwayama (Hemiptera: Psyllidae) from citrus groves of Punjab,Pakistan

The Asian citrus psyllid, Diaphorina citri Kuwayama being a vector of huanglongbing (HLB), citrus greening disease is the most destructive pest of citrus and the management of D. citri is crucial for successful control of HLB. We evaluated adult populations of D. citri from twelve districts of Punjab, Pakistan for resistance to seven different insecticides. Different levels of resistance ratios were observed for all insecticides (chlorpyrifos, bifenthrin, imidacloprid, acetamiprid, thiamethoxam, nitenpyram and chlorfenapyr). Field collected populations of D. citri were highly resistant to imidacloprid as compared to the susceptible population. The resistance ratios were in range of 236.6–759.5, 55.5–212.8, 13.1–46.4, 31.4–216.7, 8.6–89.4-fold for imidacloprid, acetamiprid, chlorfenapyr, nitenpyram, and thiamethoxam, respectively and 39.8–107.1 and 32.7–124.5-fold in case of conventional insecticides i.e., bifenthrin and chlorpyrifos, respectively. Nitenpyram and thiamethoxam, with no or very low resistance should be used in combination or in rotation with other pest management tactics for managing resistance in D. citri. The correlation analysis of the LC₅₀'s of insecticides showing positive and negative correlations among different insecticides in all tested populations, suggests mechanism of cross-resistance. Imidacloprid showed a positive correlation with acetamaprid, but a negative correlation with thiamethoxam from the neonicotenoid group, while the resistance to chlorfenpyr positively correlated with chlorpyrifos and bifenthrin in the pyrethroid group. Multiple resistance mechanisms could be the reason behind the development of such a high resistance in the D. citri.     

High level of metaflumizone resistance and multiple insecticide resistance in field populations of Spodoptera exigua (Lepidoptera: Noctuidae) in Guangdong Province,China

Spodoptera exigua is a phytophagous pest that causes critical economic losses in vegetable crops, and insecticides are commonly used against it in vegetable growing areas. However, excessive and frequent applications of insecticides cause resistance in S. exigua. The current resistance in field populations of S. exigua collected from Huizhou, Guangdong Province, China to 12 insecticides was investigated. S. exiguahad developed very high resistance to lambda cyhalothrin (2925- to 3449-fold), chlorpyrifos (>1786-fold), emamectin benzoate (174- to 867-fold), and metaflumizone (60.3- to 942-fold). High resistance to tebufenozide (51.5- to 75.4-fold) and chlorfluazuron (60.4- to 63.0-fold) was also found. Synergism assays revealed that the resistance to metaflumizone and lambda cyhalothrin was associated with esterase and microsomal oxidases, respectively. The resistance to emamectin benzoate was not affected by detoxification enzymes inhibitors and might be conferred by other mechanisms. The selection of the field population by metaflumizone for 10generations in the laboratory resulted in a 6.1-fold increase in metaflumizone resistance but did not lead to increases in resistance to other insecticides. After metaflumizone selection, susceptibilities to spinosad and endosulfan did not change, and the susceptibilities to indoxacarb, methomyl, pyridalyl, tebufenozide, chlorfluazuron, emamectin benzoate and lambda cyhalothrin decreased slightly. However, no statistically significant differences in the resistance levels were observed among the selected population, its starting strain and the unselected strain. The resistance to chlorantraniliprole noticeably decreased in unselected strain and the strain subjected to selection for 10 generations compared with their starting strains. Lack of cross-resistance to tested insecticides suggested the involvement of multiple mechanisms of resistance and the need for wise application of these insecticides for the management of S. exigua.     

长江流域稻区二化螟抗药性监测

2008-2009年期间,采用毛细管点滴法测定了浙、苏、皖、湘、鄂、川、豫等7省17个种群二化螟4龄幼虫对常用杀虫剂的抗性,结果表明:长江流域稻区二化螟对杀虫剂的抗性分布存在明显的区域性。高抗区浙江南部的苍南、瑞安、江山二化螟种群对20世纪70-90年代广泛使用的沙蚕毒素类的杀虫单(抗性倍数43.2～177.0倍)和有机磷类的三唑磷(238.7～728.1倍)、毒死蜱(31.7～57.8倍)均产生了高-极高水平抗性,且对近年来开始广泛使用的氟虫腈(11.2～24.7倍)和阿维菌素(5.9～7.1倍)也产生了中等或低水平抗性;中抗区的安徽庐江、湖南攸县、江苏高淳种群对三唑磷产生极高水平抗性(203.2～379.0倍),对杀虫单(18.3～48.8倍)和毒死蜱(29.8倍)产生了中等-高水平抗性,对氟虫腈(4.4倍)和阿维菌素(4.1～4.7倍)为敏感性降低;低抗区除江苏仪征种群对毒死蜱(45.2倍)、安徽和县种群对三唑磷(50.0倍)开始产生高水平抗性外,对其他杀虫剂为敏感-中等水平抗性,对氟虫腈和阿维菌素为敏感;敏感区的河南信阳、江苏连云港、四川武胜种群除对个别杀虫剂(如杀虫单)为低水平抗性外,对其他大多数杀虫剂为敏感-敏感性降低。还讨论了按抗性分布的区域性来制定相应的抗性治理方案。     

杀虫剂对新入侵海南草地贪夜蛾种群幼虫的毒力

草地贪夜蛾是2019年1月新入侵我国云南的重大农业害虫,4月首次在海口玉米田中剥查发现该虫。草地贪夜蛾严重威胁到海南本地的鲜玉米生产,筛选出具有较高毒力水平的化学药剂防治该虫迫在眉睫。本文采用浸叶法测定了15种杀虫剂对草地贪夜蛾幼虫的毒力。实验结果表明,采用较低浓度的甲维盐（5 mg/L,24 h）和多杀菌素（5 mg/L,24 h）,以及较高浓度氯虫苯甲酰胺（50 mg/L,72 h）和辛硫磷（100 mg/L,72 h）时,对草地贪夜蛾幼虫的致死率达100%,这4种杀虫剂在24 h的LC₅₀分别为0.28、0.31、9.77和11.7 mg/L;其他种类杀虫剂如灭多威、吡丙醚、氟虫腈、啶虫脒、阿维菌素、高效氯氰菊酯和虱螨脲,在100 mg/L浓度水平下,72 h对草地贪夜蛾幼虫的校正死亡率分别为100%、96.67%、88.33%、86.11%、81.67%、80.83%和80.09%。表明了可选用甲维盐、多杀菌素、氯虫苯甲酰胺和辛硫磷作为主要成分的杀虫剂,并组合其他种类杀虫剂,作为当前防治草地贪夜蛾幼虫主要防治药剂。     

Monitoring resistance of Helicoverpa armigera to different insecticides used in cotton in Spain

Helicoverpa armigera is the key pest of cotton in Spain, resulting in many insecticide treatments against it. The resistance status of H. armigera to different insecticides currently used in cotton was evaluated in Spain in two different seasons, 1999 and 2004. Four populations were tested in total, two in each season. Toxicological bioassays were conducted in the laboratory, and performed on third instar larvae by topical application of the insecticides. LD₅₀'s were estimated by probit analysis and resistance factors (RF) were calculated at the LD₅₀ level. Four insecticides were evaluated, but only endosulfan reached a moderate resistance level (RF = 11.4), and the others (methomyl, chlorpyrifos and lambda-cyhalothrin) showed low resistance (RF between 1.9 and 6.0). Such results indicate the generally low resistance of H. armigera to most of the insecticides used against this pest in cotton in Spain. Possible explanations for this situation are discussed.     

新烟碱类及其他稻田杀虫剂对褐飞虱的室内药效评价

【目的】系统评价市场上常用杀虫剂对褐飞虱不同虫态的作用特性，为选择对口药剂进行防治提供依据。【方法】采用稻苗浸渍法，在室内条件下测定了9种新烟碱类药剂和10种其他类型杀虫剂对褐飞虱不同虫态的杀虫活性、速效性和持效性。【结果】1)杀虫活性：不同杀虫剂活性存在显著差异。其中，烯啶虫胺、噻虫胺、毒死蜱、氟啶虫胺腈、呋虫胺和环氧虫啶活性最好，其次为哒嗪硫磷、乙基多杀菌素、吡蚜酮、异丙威，阿维菌素；其余药剂中噻虫嗪、甲维盐、氟啶虫酰胺对2~3龄若虫有一定活性而对4~5龄虫活性差，噻嗪酮、吡虫啉、噻虫啉、啶虫脒、氯噻啉对两种虫态的活性均较差。2)速效性：毒死蜱、哒嗪硫磷的速效性最好，异丙威、呋虫胺、烯啶虫胺、噻虫胺等次之，吡蚜酮最差。3)持效性：吡蚜酮、呋虫胺、烯啶虫胺、噻虫胺、环氧虫啶持效期>15 d，其中吡蚜酮最好，药后0、5和10 d连续3批接的试虫死亡率无显著差异。4)成虫：呋虫胺、烯啶虫胺、噻虫胺、环氧虫啶、毒死蜱、异丙威、吡蚜酮对雌雄成虫均有效，类似于若虫。5)卵：毒死蜱、烯啶虫胺、呋虫胺和噻虫胺对卵及孵化的若虫均有效；吡蚜酮、环氧虫啶、异丙威等无明显杀卵活性，但吡蚜酮对孵化若虫有较好的杀虫活性。【结论】19种药剂中，适于褐飞虱防治的有吡蚜酮、烯啶虫胺、呋虫胺、噻虫胺、环氧虫啶、氟啶虫胺腈、毒死蜱、哒嗪硫磷、异丙威共9种。其中，吡蚜酮持效性最佳且对卵之外各虫态活性较好，但速效性最差。呋虫胺、烯啶虫胺、噻虫胺和环氧虫啶等的速效性、持效性均较突出，且前三者对各虫态均有效。氟啶虫胺腈杀虫活性和速效性均好，但持效性差于新烟碱类。毒死蜱和哒嗪硫磷可单独或在防治其他害虫时兼防治褐飞虱，其中毒死蜱速效性最好，适合于大虫量时快速压低虫量。异丙威杀虫活性弱于新烟碱类，但速效性强于新烟碱类药剂，适合与吡蚜酮等混用或复配。此外，用于鳞翅目害虫防治的乙基多杀菌素、阿维菌素、甲维盐对褐飞虱有一定活性，适合防治其他害虫时兼治褐飞虱。而其余药剂如吡虫啉、噻嗪酮、噻虫嗪等7种药剂不适用于褐飞虱的防治。     

新烟碱类及其他稻田杀虫剂对褐飞虱的室内药效评价

【目的】 系统评价市场上常用杀虫剂对褐飞虱不同虫态的作用特性,为选择对口药剂进行防治提供依据。【方法】 采用稻苗浸渍法,在室内条件下测定了9种新烟碱类药剂和10种其他类型杀虫剂对褐飞虱不同虫态的杀虫活性、速效性和持效性。【结果】 1)杀虫活性：不同杀虫剂活性存在显著差异。其中,烯啶虫胺、噻虫胺、毒死蜱、氟啶虫胺腈、呋虫胺和环氧虫啶活性最好,其次为哒嗪硫磷、乙基多杀菌素、吡蚜酮、异丙威,阿维菌素;其余药剂中噻虫嗪、甲维盐、氟啶虫酰胺对2~3龄若虫有一定活性而对4~5龄虫活性差,噻嗪酮、吡虫啉、噻虫啉、啶虫脒、氯噻啉对两种虫态的活性均较差。2)速效性：毒死蜱、哒嗪硫磷的速效性最好,异丙威、呋虫胺、烯啶虫胺、噻虫胺等次之,吡蚜酮最差。3)持效性：吡蚜酮、呋虫胺、烯啶虫胺、噻虫胺、环氧虫啶持效期>15 d,其中吡蚜酮最好,药后0、5和10 d连续3批接的试虫死亡率无显著差异。4)成虫：呋虫胺、烯啶虫胺、噻虫胺、环氧虫啶、毒死蜱、异丙威、吡蚜酮对雌雄成虫均有效,类似于若虫。5)卵：毒死蜱、烯啶虫胺、呋虫胺和噻虫胺对卵及孵化的若虫均有效;吡蚜酮、环氧虫啶、异丙威等无明显杀卵活性,但吡蚜酮对孵化若虫有较好的杀虫活性。【结论】 19种药剂中,适于褐飞虱防治的有吡蚜酮、烯啶虫胺、呋虫胺、噻虫胺、环氧虫啶、氟啶虫胺腈、毒死蜱、哒嗪硫磷、异丙威共9种。其中,吡蚜酮持效性最佳且对卵之外各虫态活性较好,但速效性最差。呋虫胺、烯啶虫胺、噻虫胺和环氧虫啶等的速效性、持效性均较突出,且前三者对各虫态均有效。氟啶虫胺腈杀虫活性和速效性均好,但持效性差于新烟碱类。毒死蜱和哒嗪硫磷可单独或在防治其他害虫时兼防治褐飞虱,其中毒死蜱速效性最好,适合于大虫量时快速压低虫量。异丙威杀虫活性弱于新烟碱类,但速效性强于新烟碱类药剂,适合与吡蚜酮等混用或复配。此外,用于鳞翅目害虫防治的乙基多杀菌素、阿维菌素、甲维盐对褐飞虱有一定活性,适合防治其他害虫时兼治褐飞虱。而其余药剂如吡虫啉、噻嗪酮、噻虫嗪等7种药剂不适用于褐飞虱的防治。     

新烟碱类及其他稻田杀虫剂对褐飞虱的室内药效评价

【目的】系统评价市场上常用杀虫剂对褐飞虱不同虫态的作用特性,为选择对口药剂进行防治提供依据。【方法】采用稻苗浸渍法,在室内条件下测定了9种新烟碱类药剂和10种其他类型杀虫剂对褐飞虱不同虫态的杀虫活性、速效性和持效性。【结果】1)杀虫活性:不同杀虫剂活性存在显著差异。其中,烯啶虫胺、噻虫胺、毒死蜱、氟啶虫胺腈、呋虫胺和环氧虫啶活性最好,其次为哒嗪硫磷、乙基多杀菌素、吡蚜酮、异丙威,阿维菌素;其余药剂中噻虫嗪、甲维盐、氟啶虫酰胺对2~3龄若虫有一定活性而对4~5龄虫活性差,噻嗪酮、吡虫啉、噻虫啉、啶虫脒、氯噻啉对两种虫态的活性均较差。2)速效性:毒死蜱、哒嗪硫磷的速效性最好,异丙威、呋虫胺、烯啶虫胺、噻虫胺等次之,吡蚜酮最差。3)持效性:吡蚜酮、呋虫胺、烯啶虫胺、噻虫胺、环氧虫啶持效期>15d,其中吡蚜酮最好,药后0、5和10 d连续3批接的试虫死亡率无显著差异。4)成虫:呋虫胺、烯啶虫胺、噻虫胺、环氧虫啶、毒死蜱、异丙威、吡蚜酮对雌雄成虫均有效,类似于若虫。5)卵:毒死蜱、烯啶虫胺、呋虫胺和噻虫胺对卵及孵化的若虫均有效;吡蚜酮、环氧虫啶、异丙威等无明显杀卵活性,但吡蚜酮对孵化若虫有较好的杀虫活性。【结论】19种药剂中,适于褐飞虱防治的有吡蚜酮、烯啶虫胺、呋虫胺、噻虫胺、环氧虫啶、氟啶虫胺腈、毒死蜱、哒嗪硫磷、异丙威共9种。其中,吡蚜酮持效性最佳且对卵之外各虫态活性较好,但速效性最差。呋虫胺、烯啶虫胺、噻虫胺和环氧虫啶等的速效性、持效性均较突出,且前三者对各虫态均有效。氟啶虫胺腈杀虫活性和速效性均好,但持效性差于新烟碱类。毒死蜱和哒嗪硫磷可单独或在防治其他害虫时兼防治褐飞虱,其中毒死蜱速效性最好,适合于大虫量时快速压低虫量。异丙威杀虫活性弱于新烟碱类,但速效性强于新烟碱类药剂,适合与吡蚜酮等混用或复配。此外,用于鳞翅目害虫防治的乙基多杀菌素、阿维菌素、甲维盐对褐飞虱有一定活性,适合防治其他害虫时兼治褐飞虱。而其余药剂如吡虫啉、噻嗪酮、噻虫嗪等7种药剂不适用于褐飞虱的防治。