浓硫酸纯化-气相色谱法测定土壤中拟除虫菊酯农药残留

建立了土壤中拟除虫菊酯类农药新的前处理方法。样品以乙腈提取,浓硫酸-乙醇进行纯化,毛细管柱气相色谱法测定土壤中的拟除虫菊酯农药。结果表明:4种菊酯在3种土壤样品中的添加回收率在84.14%～105.51%之间,变异系数为1.24%～5.82%。该方法具有省时、省溶剂、操作简单、纯化效果好、实用性强的特点。     

四种菊酯类杀虫剂对枸杞蚜虫线粒体膜流动性的影响

为明确菊酯类杀虫剂对昆虫线粒体膜流动性的影响，以1，6-二苯基-1，3，5-己三烯（1，6-diphenyl-1，3，5-hexatriene，DPH）为荧光探剂，采用荧光偏振法研究了4种菊酯类杀虫剂对枸杞蚜虫Aphis sp.线粒体膜流动性的影响。结果表明，4种菊酯类杀虫剂对枸杞蚜虫线粒体膜流动性均有显著影响，其荧光偏振度显著增大，线粒体膜流动性显著减小。当药剂浓度为100 μmol/L时，对照组枸杞蚜虫线粒体膜的荧光偏振度为0.239，高效氯氰菊酯的影响最大，线粒体膜的荧光偏振度为0.315，联苯菊酯的影响最小，线粒体膜的荧光偏振度为0.287。4种菊酯类杀虫剂对线粒体膜流动性的影响都存在一定的浓度效应，当药剂浓度在0~100 μmol/L范围内，浓度越大影响越大。4种菊酯类杀虫剂在不同温度下对枸杞蚜虫线粒体膜流动性的影响不同，高效氯氰菊酯、联苯菊酯和甲氰菊酯对线粒体膜流动性的影响基本不受温度影响，而氯菊酯在高温条件下产生的影响大，在低温条件下产生的影响小，表现为明显的正温度系数。表明DPH可以作为荧光探剂研究枸杞蚜虫线粒体膜的流动性。     

Public safety aspects of pyrethroid insecticides used in West Nile virus-carrying mosquito control

West Nile virus is becoming increasingly prevalent in the USA, causing fever, encephalitis, meningitis and many fatalities. Spread of the disease is reduced by controlling the mosquito vectors by a variety of means, including the use of pyrethroid insecticides, which are currently under scrutiny for potential carcinogenic effects in humans. Pyrethrins and resmethrin, a pyrethroid, have been shown to cause tumours in rat and mouse models respectively. However, the tumours appear to be caused by liver enzyme induction and hypertrophy rather than genotoxicity, and the results are therefore unlikely to be applicable to humans. Nonetheless, for resmethrin, the US Environmental Protection Agency (EPA) has concluded that there is a likely risk of carcinogenicity in humans, requiring the manufacturers to provide more detailed data to prove that it can be used safely in vector control. Reproductive toxicity of resmethrin in the rat is also discussed.     

Use of pyrethroid analogues to identify key structural features for enhanced esterase resistance in Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

It has been reported previously that the major resistance mechanism to pyrethroid insecticides by the cotton bollworm Helicoverpa armigera (Hübner) in Australia is a consequence of overproduction of esterase isoenzymes. This paper reports structure-activity relationships that support such a view, based on in vivo bioassays conducted with a range of pyrethroid structures containing a variety of acid and alcohol moieties and the correlation with in vitro esterase inhibition assays against the same structures, and identifies the critical regions of the molecule with regard to esterase inhibition, and hence resistance. The implications of this work in terms of possible resistance management are evaluated and discussed.     

Permethrin toxicity in cats: a retrospective study of 20 cases

OBJECTIVE: Permethrin is a synthetic pyrethroid widely used in flea control products for small animals. Accidental toxicity can occur with off-label usage, and cats are particularly susceptible. METHODS: Retrospective study of 20 cases of permethrin toxicity in cats treated at an emergency clinic in Brisbane, Queensland from October 2004 to June 2005. RESULTS: The diagnosis of permethrin toxicity was made on the basis of a history of exposure and characteristic clinical signs, including seizures, muscle fasciculations, and tremors. Decontamination and appropriate seizure or muscle fasciculation control were the basis of treatment. The outcome was good after rapid intervention and 19 of the 20 cats were successfully treated, with the only death occurring in a kitten for which treatment was delayed for 24 h. No long-term complications were reported by the cats' owners at 4-month follow-up after discharge from hospital. CONCLUSIONS: Owner education, together with more appropriate product labelling, may help eliminate this problem in the future.     

Uncommon associations in target resistance among French populations of Myzus persicae from oilseed rape crops

Within the framework of a molecular exploration of target resistance in populations of Myzus persicae on oilseed rapes in France, (1) the S431F mutation (coding gene ace2), although previously reckoned to be rare, revealed to be frequent, (2) M918L (phenotypically characterised) and L932F (both on para) were found for the first time in M. persicae, and (3) a linkage was revealed between M918L and S431F. While until recently populations developing on French oilseed rapes were dominated by genotypes possessing pyrethroid target resistance and esterase overproduction, to date a different type of dominating genotype, equipped with carbamate and pyrethroid target resistance, seems to be invading such fields.     

Dissipation of three organochlorine and four pyrethroid pesticides sprayed in a greenhouse environment during hydroponic cultivation of gerbera

A wide range of pesticides (insecticides, acaricides and fungicides) is used in the hydroponic cultivation of gerbera. The fate and behaviour of some of these commonly used pesticides (organochlorine and pyrethroid insecticides/acaricides) in a greenhouse installation was investigated. The concentrations of endosulfan, dicofol, tetradifon, permethrin, bifenthrin, cypermethrin and deltamethrin in the air of the greenhouse were related to their physicochemical properties and respective application rates. Of these compounds, endosulfan exhibited the highest concentration in the greenhouse air 2 h after application (10 microg m(-3)), due to its highest volatility; afterwards, up to 12 h post-application, a rapid decrease was recorded which finally led to a concentration of 0.41 microg m(-3) at 6 days post-application. Dicofol exhibited the same trend of dissipation in the greenhouse air; its concentration decreased from 0.27 microg m(-3) immediately after the application to 0.12 microg m(-3) at 6 days post-application. Tetradifon, bifenthrin and permethrin were found at concentrations lower than 0.1 microg m(-3) at 2 h post-application, and cypermethrin and deltamethrin could not be detected. The concentrations of all the above pesticides in the drain water of the open hydroponic system were relatively high immediately after application and decreased rapidly during the following 3 days. In the closed hydroponic system, all the pesticides accumulated in the nutrient solution during the first 24 h after application and slowly decreased in concentration over the following 3 days. The spray operators applying these pesticides were exposed to rather high concentrations and the spray deposits were monitored on the chest and forehead of the operator. Endosulfan exhibited the highest concentrations of the seven pesticides. The organochlorine pesticides (endosulfan, dicofol and tetradifon) were usually detected at higher concentrations on the chest than on the forehead of the operator; pyrethroids were detected at higher concentrations on the forehead than on the chest of the operator.     

Circadian dynamics of locomotor activity and deltamethrin susceptibility in the pine weevil,Hylobius abietis

Rhythmic locomotor activity and daily susceptibility to deltamethrin were tested in the pine weevil,Hylobius abietis (L.) (Coleoptera, Curculionidae), a pest of young conifer plants. In constant darkness, beetles revealed a free-running circadian pattern of locomotor activity (average period 22h : 20min). Under long photoperiod, L:D 18:6, entrainment of motor activity was observed. In the entrained population of the weevils, a peak of locomotor activity occurred at about the beginning of the dark phase, and the minimum occurred in the middle of the light phase. Fluctuations of susceptibility to a standard dose of deltamethrin (0.5 μg/g body weight) varied across the day, and were inversely correlated to the changes in locomotor activity. The importance of considering the daily organization of insect biology in studying insect resistance to pesticides is re-emphasized. 3 www.csa.com. The following databases were screened: Animal Behaviour Abstracts, AGRICOLA, Aquatic Science and Fishery Abstracts, Biological Sciences, Ecology Abstracts, Entomology Abstracts, Environmental Science and Pollution Abstracts, Health and Safety Science Abstracts, Pollution Abstracts, Water Resource Abstracts, Toxicology Abstracts, TOXLINE.     

浓硫酸净化-气相色谱法检测茶叶中α-硫丹和拟除虫菊酯类农药残留

建立了一种茶叶中硫丹和5种拟除虫菊酯类农药(联苯菊酯、高效氯氟氰菊酯、氯氰菊酯、溴氰菊酯和氰戊菊酯)残留分析的新方法。样品以乙腈提取,浓硫酸-乙醇净化,毛细管柱气相色谱法(GC-ECD)测定。结果表明:在0.005～0.5 mg/kg添加水平内,4种茶叶样品中α-硫丹和5种拟除虫菊酯农药的添加回收率在81.6%～105.9%之间,相对标准偏差(RSD)为0.52%～13.0%(n=3)。α-硫丹和5种拟除虫菊酯农药在4种茶叶中的定量限(LOQ)均为0.005 mg/kg。本方法杂质干扰少,准确度及灵敏度满足农药残留检测要求,对检测硬件要求低,适用于茶叶中α-硫丹及拟除虫菊酯类农药残留的分析。