菊酯类杀虫剂对几种赤眼峰的毒力测定

采用药膜法测定了溴氰菊醋、甲氰菊酯、氰戊菊酯和三氟氯氰菊酯对广赤眼峰（ＴｒｉｃｈｏｇｒａｍｍａｅｖａｎｅｓｃｅｎｓＷｅｓｔｗｏｏｄ）、螟黄赤眼峰（Ｔ．ｃｏｎｆｕｓｕｍＷｉｇｇｉａｎｉ）、松毛虫赤眼峰（Ｔ．ｄｅｎｄｒｏｌｉｍｉＭａｓｔｓ．）成蜂的毒力。结果表明，不同药剂对同一种赤眼峰成蜂的毒力不同；不同赤眼蜂种群的成峰对同一药剂的反应差异也较大，其中溴氰菊酯的毒力最大（ＬＣ＿（５０）＜２．３０μｇ·ｍＬ￣（－１）），甲氰菊酯相对较小（ＬＣ＞１２．５０μｇ·ｍＬ￣（－１））；３种赤眼峰中，以广赤眼蜂对药剂反应较迟钝，忍受能力较强。     

Management of resistance to pesticides in cotton pests

Abstract

In recent years, nationwide insecticide resistance management (IRM) strategies in Zimbabwe, Egypt and Australia have successfully overcome existing resistance problems on cotton and prevented further outbreaks in some key pests. These strategies, which rely heavily on pragmatic assumptions regarding the efficacy of counter‐measures and the biology of the pest, relate little to theoretical models of resistance management whose tenets have so far not been experimentally appraised. These IRM strategies are compared with a simple but rigid programme used throughout Francophone countries of Africa that has successfully controlled the pest complex on cotton and increased yield without eliciting resistance in any pests. We examine the motivations, philosophies and logistics of these control programmes on cotton, and outline scope for improvements to existing and future IRM.     

淡色库蚊对拟除虫菊酯抗性与kdr等位基因频率的关系

利用接触筒法检测淡色库蚊6个野外种群成蚊对溴氰菊酯、高效氯氰菊酯和氯菊酯的抗性水平,同时利用PASA(PCR amplification of specific alleles)方法检测每个种群kdr等位基因的频率。结果表明:不同种群的溴氰菊酯抗性水平与抗性等位基因频率有显著的相关性(R2=0.836,P=0.011),但高效氯氰菊酯和氯菊酯抗性水平与抗性等位基因频率无显著的相关性(R2分别为0.493和0.530,P值分别为0.120和0.101);对3种拟除虫菊酯抗性平均值直线回归分析显示,抗性等位基因频率与生物测试结果呈显著直线相关(R2=0.840,P=0.010)。     

Efficacy of various pyrethroid structures against a highly metabolically resistant isogenic strain of Helicoverpa armigera (Lepidoptera: Noctuidae) from China

BACKGROUND: Resistance to pyrethroids and other types of insecticides in Helicoverpa armigera (Hübner) has been documented in many countries. The isolation of specific resistance mechanisms in isogenic strains is an optimal approach to investigate cross-resistance pattern, and to validate resistance breaking pyrethroids. In this study an isogenic metabolic resistance CMR strain was successfully isolated from a field pyrethroid-resistant population of H. armigera. With this strain, cross-resistance among 19 pyrethroid insecticides with varying chemical structures was analysed. RESULTS: Resistance to pyrethroids in the CMR strain was likely to be due to enhanced oxidative metabolism. The most significant cross-resistance in the CMR strain was between pyrethroids such as fenvalerate, tau-fluvalinate and flumethrin characterised by having both phenoxybenzyl and aromatic acid moieties. Substitution of the phenoxybenzyl group with a polyfluorobenzyl group, as in tefluthrin, benfluthrin and transfluthrin, overcame most of this resistance. CONCLUSION: The findings in this study support the assertion that it is possible to find pyrethroids that are active against resistant populations. Such pyrethroids could be considered as possible partners or resistance breaking pyrethroids in a pyrethroid resistance management programme for H. armigera in China and in other Asian countries where the oxidative metabolism resistance is a dominant mechanism.     

固相萃取与GC-μECD法测定香蕉中有机氯和拟除虫菊酯类农药残留

【目的】利用气相色谱—微电子捕获方法（GC-μECD）建立可同时检测香蕉中有机氯和拟除虫菊酯类农药的方法,为香蕉的食用安全提供保障。【方法】香蕉中有机氯和拟除虫菊酯类农药残留经乙腈溶液萃取分层,乙腈相浓缩后过弗罗里硅土柱净化,采用丙酮—正己烷溶液5mL淋洗,淋洗液经氮吹仪吹干后,用正己烷定容至5mL,供GC测定。将13种标液混合稀释成1.000μg/mL,六六六、滴滴涕、氯氰菊酯、氟氰戊菊酯、氰戊菊酯和溴氰菊酯稀释为0.005、0.010、0.020、0.040、0.080、0.100、0.200μg/mL,百菌清为0.005、0.010、0.020、0.040、0.080μg/mL,配制成混合标准溶液,以峰面积为纵坐标、质量浓度为横坐标绘制标准曲线图。香蕉样品中加标浓度分3个水平：六六六、滴滴涕为分别0.005、0.010、0.050mg/kg,百菌清、氯氰菊酯、氟氰戊菊酯、氰戊菊酯和溴氰菊酯为分别0.010、0.050、0.100mg/kg进行回收率试验。根据最低加标浓度基线噪声的3倍换算各分析物的最低仪器检出限。【结果】各曲线呈良好线性关系,仪器检出限为0.5-5.0μg/L,回收率为70.4%-118.7%,相对标准偏差为2.45%-11.50%。【结论】GC-μECD方法可同时检测香蕉中13种有机氯和拟除虫菊酯类农药残留,且具有精密度和准确度高、操作简单方便、分离效果好、回收率高、重现性好等优点,适合香蕉农药残留的检测。     

Effect of foliar applications of some insecticides onBemisia tabaci, predators and parasitoids: Implications in its management in Pakistan

Three experiments were carried out during three consecutive years to evaluate 19 insecticides and 12 tank mixtures of different groups of insecticides against the whiteflyBemisia tabaci and its predators and parasitoids under field conditions in cotton. In the first experiment, the whitefly population was lower in treatments with thiacloprid and higher in those with black warrant (a.i. alcohol) and cypermethrin; the number of predators was higher with Agri-50 and spinosad and lowest with cypermethrin, whereas percent parasitism was higher with thiacloprid and lower with methamidophos. In the second experiment, the whitefly population was lower in treatments with buprofezin, pyriproxyfen and diafenthiuron and higher in those with endosulfan, imidacloprid and thiamethoxam; the number of predators was higher with pyriproxyfen and lower with thiamethoxam, whereas percent parasitism was higher with pyriproxyfen and lower with thiamethoxam. In the third experiment, the whitefly population was lower in a treatment mixture with buprofezin + fenpropathrin and higher in that with thiamethoxam + chlorpyrifos; the number of predators was higher with buprofezin + fenpropathrin and lower with deltamethrin + triazophos and deltamethrin + chlorpyrifos, whereas percent parasitism was higher with the mixture of pyriproxyfen + chlorpyrifos and lower in imidacloprid + chlorpyrifos, betacyfluthrin + triazophos, and deltamethrin + triazophos. Effective use of these insecticides to manage whitefly infestations and to save predators and parasitoids is discussed. http:www.phytoparasitica.org posting August 7, 2008.     

Effects of insecticide exposure on movement and population size estimates of predatory ground beetles (Coleoptera: Carabidae)

BACKGROUND: Estimates of arthropod population size may paradoxically increase following insecticide applications. Research with ground beetles (Coleoptera: Carabidae) suggests that such unusual results reflect increased arthropod movement and capture in traps rather than real changes in population size. However, it is unclear whether direct (hyperactivity) or indirect (prey-mediated) mechanisms produce increased movement. RESULTS: Video tracking of Scarites quadriceps Chaudior indicated that brief exposure to lambda-cyhalothrin or tefluthrin increased total distance moved, maximum velocity and percentage of time moving. Repeated measurements on individual beetles indicated that movement decreased 240 min after initial lambda-cyhalothrin exposure, but increased again following a second exposure, suggesting hyperactivity could lead to increased trap captures in the field. Two field experiments in which ground beetles were collected after lambda-cyhalothrin or permethrin application attempted to detect increases in population size estimates as a result of hyperactivity. Field trials used mark-release-recapture methods in small plots and natural carabid populations in larger plots, but found no significant short-term (<6 day) increases in beetle trap captures. CONCLUSION: The disagreement between laboratory and field results suggests mechanisms other than hyperactivity may better explain unusual changes in population size estimates. When traps are used as a primary sampling tool, unexpected population-level effects should be interpreted carefully or with additional data less influenced by arthropod activity.     

Pyrethroids, knockdown resistance and sodium channels

Knockdown resistance to DDT and the pyrethrins was first described in 1951 in the housefly (Musca domestica L.). This trait, which confers reduced neuronal sensitivity to these insecticides, was subsequently shown to confer cross-resistance to all synthetic pyrethroid insecticides that have been examined to date. As a consequence, the worldwide commercial development of pyrethroids as a major insecticide class over the past three decades has required constant awareness that pyrethroid overuse has the potential to reselect this powerful resistance mechanism in populations that previously were resistant to DDT. Demonstration of tight genetic linkage between knockdown resistance and the housefly gene encoding voltage-sensitive sodium channels spurred efforts to identify gene mutations associated with knockdown resistance and understand how these mutations confer a reduction in the sensitivity of the pyrethroid target site. This paper summarizes progress in understanding pyrethroid resistance at the molecular level, with particular emphasis on studies in the housefly.     

Resistance to chlorpyrifos and lambda-cyhalothrin along with detoxifying enzyme activities in field-collected female populations of European red mite

The levels of susceptibility of populations of the European red mite Panonychus ulmi (Koch) (Acarina: Tetranychidae) collected from apple orchards in the Bursa region of Turkey to the insecticides chlorpyrifos and lambda-cyhalothrin, were determined by a petri leaf disk—Potter spray tower method. When compared with the susceptible population, resistance ratios at the LC₅₀ level ranged from 6.0- to 35.6-fold, and from 0.7- to 5.7-fold for chlorpyrifos and lambda-cyhalothrin, respectively. Kinetic parameters of general esterase activity with α-naphthyl acetate as substrate indicated that an increased activity was present in the resistant populations compared with the susceptible populations. In these strains, 1.5- and 2.2-fold higher Glutathione S-transferase (GST) activity was also detected with the substrate 1-chloro-2,4-dinitrobenzene. General esterase activity gel profiles of these populations were studied by native polyacrylamide gel electrophoresis, but no relationship between resistance ratios and band patterns was detected. The results of this study document a decreased efficacy of chlorpyrifos and lambda-cyhalothrin in field populations of P. ulmi in Turkey, possibly linked to altered activities of esterases and GST.