氯氰菊酯在土柱淋滤实验中的迁移行为

通过室内一维土柱淋滤实验,选择氯氰菊酯为淋滤液,研究其在不同介质中的穿透行为,探讨不同介质自身特性对氯氰菊酯纵向弥散行为的影响。实验依据自然降雨强度确定喷淋强度,通过改变充填介质的种类比较氯氰菊酯与氯离子在不同介质中的穿透曲线的差异。结果表明:以乳油形式广泛应用于田间的氯氰菊酯在土柱内的穿透曲线与氯离子十分接近,即氯氰菊酯在水中的迁移性能良好,对地下水有一定威胁。土壤有机质含量会引起弥散系数的降低,实验选择的2种喷淋强度对氯氰菊酯的弥散系数影响不大。     

Potentiation/antagonism of deltamethrin and cypermethrins with organophosphate insecticides in the cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae)

The joint action of pyrethroids deltamethrin and cypermethrins in combination with organophosphates ethion, profenofos, chlorpyrifos, quinalphos, and triazophos was studied on putatively resistant field populations of Helicoverpa armigera from Pakistan by using a leaf-dip method. Ethion produced a good potentiation with deltamethrin, cypermethrin, alphacypermethrin, and zetacypermethrin, whereas profenofos, chlorpyrifos, quinalphos, and triazophos exhibited an antagonism with deltamethrin as well as cypermethrins. Implications of using mixtures for counteracting insecticide resistance are discussed.     

Combined effect of cypermethrin and copper on catalase activity in soil

Background, aim, and scope  Pollution of soil environment has become a serious problem in many countries. Repeated application of bordeaux mixture and pyrethroids insecticides have led to elevated copper (Cu) and pyrethroids concentrations in vineyard surface soils. Therefore, it is recommended to evaluate the combined effect of copper and pyrethroids on soil enzymes. Our aim was to get a more comprehensive understanding of the effects of Cu and cypermethrin on the soil catalase, and to provide more information about the potential ecological risk of chemicals on the soil ecosystem. Materials and methods  The dried and sieved soil sample was first thoroughly mixed with aqueous solution of CuSO₄ 5H₂O, and acetone solution of cypermethrin according to the orthogonal design, and then incubated at 25°C for 35 days. Five concentration levels for each pollutant (Cu and cypermethrin) were studied. Control without any artificial contamination received the same amount of distilled water and acetone. Each test was conducted with three replications. Moisture in the incubated soil samples was kept at 60% of the full soil water holding capacity by weighing daily. Catalase activity was determined by back-titrating residual H₂O₂ with KMnO₄ after 7, 14, 21, 28, and 35 days. Data treatment was essentially based on analysis of the variance test. Results  During the incubation time, soil catalase activity was lower than the control samples and the result ranged from 70.64% to 100%, except for that of the two samples S6 and S13. The catalase activity in all samples was declined after application of Cu, without addition of cypermethrin. While the concentration of cypermethrin ranged from 0 to 150 mg kg^–1, without the addition of Cu, the variety of catalase activity was as follows: restrained–activated–restrained. The combined effect of cypermethrin and Cu on soil catalase activity depends largely on the concentration of pollutants. Discussion  The presumable explanation of the result that the catalase was inhibited by single Cu addition was due to: (1) complexation of the substrate, (2) combination with the protein-active groups of the enzymes, or (3) reaction with the enzyme–substrate complex. In our study, there were some differences in the catalase when soil samples were treated with a different concentration of cypermethrin. This is possibly related to the protect mechanism of soil catalase. In addition, the combined effect of cypermethrin and Cu on catalase activity is stronger than single cypermethrin, while weaker than single Cu. One of the possible explanations of this phenomenon is related with the interaction between cypermethrin and Cu. Another may be related to bioavailability. Conclusions  The combined effect of cypermethrin and Cu on soil catalase activity depends largely on the concentration of the pollutants. The magnitude and type of interaction may be strongly dependent on the level of response and the relative proportion of the components in the mixture. These factors should therefore be considered in risk assessments and in the setting of soil quality criteria. Recommendations and perspectives  Generally speaking, the influence of pesticides and heavy metals on soil is a long-term process and is closely related to soil characteristics. Much more should be done to clearly understand the mechanism of interaction between cypermethrin and Cu on soil.     

两种拟除虫菊酯类杀虫剂对萼花臂尾轮虫的急性毒性研究

[目的]研究常见拟除虫菊酯类杀虫剂氯氰菊酯和溴氰菊酯对轮虫的24、48 h急性毒性大小。[方法]以广州品系萼花臂尾轮虫为受试动物,采用标准毒性试验方法进行急性毒性试验,机率单位法测定氯氰菊酯和溴氰菊酯对轮虫的LC50值。[结果]氯氰菊酯对萼花臂尾轮虫的24、48 hLC50分别为3 376.87、5.87μg/L;溴氰菊酯对萼花臂尾轮虫的24、48 hLC50分别为594.56、74.17μg/L。[结论]氯氰菊酯和溴氰菊酯对轮虫24、48 h的急性毒性大小不同;氯氰菊酯和溴氰菊酯对轮虫的48 hLC50值比其24 hLC50值用来监测水体中的此类化学污染物更为敏感。     

混合微生物对上海青叶片上氯氰菊酯的降解特性研究

[目的]研究混合微生物对上海青叶片上氯氰菊酯的降解特性。[方法]采用大田试验方法,测定不同水浴温度、不同喷洒时间、不同降解菌浓度和不同应用天数对氯氰菊酯农药降解率的影响。[结果]该混合微生物发挥最优降解效果的水浴温度为33℃,喷洒时间为17：00,菌体浓度OD6001.0,大田施用3、5、7d后,氯氰菊酯农药的去除率分别可达61%、80%、93%。[结论]应用该混合微生物最优降解条件可有效降解氯氰菊酯农药残留。     

State-dependent modification of voltage-gated sodium channels by pyrethroids

Pyrethroids disrupt nerve function by altering the rapid kinetic transitions between conducting and nonconducting states of voltage-gated sodium channels that underlie the generation of nerve action potentials. Recent studies of pyrethroid action on cloned insect and mammalian sodium channel isoforms expressed in Xenopus laevis oocytes show that in some cases pyrethroid modification is either absolutely dependent on or significantly enhanced by repeated channel activation. These use-dependent effects have been interpreted as evidence of preferential binding of at least some pyrethroids to the open, rather than resting, state of the sodium channel. This paper reviews the evidence for state-dependent modification of insect and mammalian sodium channels expressed in oocytes by pyrethroids and considers the implications of state-dependent effects for understanding the molecular mechanism of pyrethroid action and the development and testing of models of the pyrethroid receptor.     

50%毒·氯乳油对韭菜迟眼蕈蚊幼虫的室内毒力及田间防效

本文采用室内与田间试验相结合的方法,研究了50％毒·氯乳油对韭菜迟眼蕈蚊幼虫的杀虫效果。结果表明其对韭菜迟眼蕈蚊幼虫具有良好的杀虫效果,室内毒力测定LC50= 44．42mg／L;田间防治效果理想,且表现出良好的速效性及持效性,其中3 000g／hm2剂量, 药后3d的防治效果达到79．26％,药后20d防治效果仍然可以维持在80％以上。     

氯氰菊酯农药降解菌株的稳定性研究

通过氯氰菊酯农药生产车间下水道中的农药的混合微生物富集驯化培养获得降解氯氰菊酯降解菌.在富集培养基中分别传代5、10、15代,传代温度是30 ℃,pH值7.0,该混合微生物呈现不同的生长曲线.继代5代的氯氰菊酯农药降解能力为55%,继代10代的氯氰菊酯农药降解能力为52%,继代15代的氯氰菊酯农药降解能力为50%,表明该菌具有较好的降解能力稳定性.     

气相色谱法检测蜂胶中的氟胺氰菊酯和氟氯苯氰菊酯残留

[目的]建立蜂胶中氟胺氰菊酯和氟氯苯氰菊酯残留的测定方法。[方法]以石油醚为溶剂提取样品,采用凝胶渗透色谱法净化样品,采用气相色谱法测定氟胺氰菊酯和氟氯苯氰菊酯残留。[结果]匀浆提取的提取效果远远好于震荡提取的提取效果。石油醚的提取效果比石油醚-丙酮混合液的提取效果好。与丙酮-石油醚（9：1）和石油醚-乙酸乙酯（95：5）相比,石油醚-乙酸乙酯（98：2）的净化效果最理想。氟胺氰菊酯和氟氯苯氰菊酯的回收率均在69．0％～96．4％,相对标准偏差均在1．27％～7．69％,表明该方法的准确度和精密度均能达到残留分析的要求。氟胺氰菊酯和氟氯苯氰菊酯的检测限均为0．05mg/kg。[结论]该方法可以有效监控蜂胶中相应药物的残留,提高国产蜂胶的品质和国际竞争力。     

氯氰菊酯的酶促降解

阴沟肠杆菌w 10 j15经过纯培养、超声波破碎和高速离心,提取到氯氰菊酯降解酶。在实验条件下测定了降解酶对氯氰菊酯的降解特性。结果表明,降解酶在40℃、pH 7.5时对氯氰菊酯显示最大的降解活性,对氯氰菊酯的降解率为78%;它在30~50℃或pH 6.5~8.0稳定性良好。L inew eaver-Burg法做图分析表明,其酶蛋白最大降解速率Vm ax为63.69 nm o.lmL-1.m in-1,米氏常数(Km)为377.35 nm o l/mL。