Aquatic toxicity of cartap and cypermethrin to different life stages of Daphnia magna and Oryzias latipes

Cartap and cypermethrin, which are among the most widely used pesticides in many countries, are considered safe because of their low mammalian toxicity and their low persistence in the environment. However, recent findings of endocrine-disrupting effects and developmental neurotoxicity have raised concerns about the potential ecological impacts of these pesticides. We evaluated the aquatic toxicity of cartap [S,S′-(2-dimethylaminotrimethylene) bis(thiocarbamate), unspecified hydrochloride] and cypermethrin [(RS)-alpha-cyano-3-phenoxybenzyl-(1RS,3RS,1RS,3SR)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate], both individually and combined, on different life stages of the freshwater cladoceran Daphnia magna and a freshwater teleost, Japanese medaka (Oryzias latipes). The 96-hr Daphnia median effective concentrations (EC50s) for cartap and cypermethrin were 91.0 μ g/L and 0.00061 μ g/L, respectively. Rapid recovery of Daphnia was observed after short-term pulsed exposure to cartap and cypermethrin; there were no adverse effects on reproduction or survival 20 d after a 24 hr exposure to cartap up to 1240 μ g/L and cypermethrin up to 1.9 μ g/L. Chronic continuous exposure (for 21 d) of 7-d-old Daphnia to cypermethrin significantly reduced the intrinsic population growth rate in a concentration-dependent manner. However, because the intrinsic population growth rates were all above zero, populations did not decrease even at the highest experimental concentration of 200 ng/L. Exposure of Daphnia neonates (< 24 hr old) to cypermethrin for 21 d caused significant, sub-lethal reproduction-related problems, such as increased time to first brood, reduced brood size, and reduced total brood number, at 0.0002, 0.002, and 0.2 ng/L cypermethrin, but the intrinsic population growth rate was not significantly affected. Oryzias latipes was relatively more resistant to both pesticides. In particular, embryos appeared to be more resistant than juveniles or adults, which may be partly due to the protective role of the chorion. The incidence of larval fish deformity was significantly higher after a 96 hr exposure to as low as 250 μ g/L of cartap or 40 μ g/L of cypermethrin. The mixture of both compounds showed no synergistic toxicity. The extremely high acute-to-chronic ratio suggests that the standard acute lethal toxicity assessment might not reflect the true environmental hazards of these frequently used pesticides. Ecological hazard assessments of long-term low dose or pulsed exposures to cartap and cypermethrin may reveal more realistic consequences of these compounds in surface water.     

The synthetic pyrethroid isomers II. Biological activity

Abstract

Pure optical isomers of phenothrin, permethin and cypermethrin were synthesised and tested on a wide spectrum of insects (Blattella germanica, Leptinotarsa decemlineata, Tribolium confusum, Oncopeltus fasciatus, Musca domestica, Aedes aegypti). Our results suggest that in the structurally related series phenothrin, permethrin and cypermethrin the chemical modifications had only a small influence on intrinsic activity of the compounds at the target site. The activity of piperonylbutoxide synergised 1Rtrans phenothrin and 1Rcis permethrin (LD₅₀=1.2 ng/fly in both cases) is in a similar range to the most active 1RcisS cypermethrin isomer alone or with PB (LD₅₀=0.9 and 0.4 ng/fly, respectively). Some cypermethrin isomers considered previously to be totally inactive show significant activity depending on the tested insect species. The 1ReisR and 1RtransR isomers proved to be as active as the most potent isomers on mosquito. A similarly unexpected result was that in the case of mosquito all four trans isomers were significantly more active than the corresponding eis isomers.

The superiority of the (S)‐α configuration over (R)‐α was found. It does not result from a higher intrinsic activity at the target site, but rather from the enhanced metabolic resistance of (S)‐α‐esters to ester cleavage as confirmed by Synergist studies. The activity of the two most potent stereoisomers, 1ReisS and 1RtransS, could not be elevated by quinalphos, while the inactive 1ScisR and 1StransR isomers showed significant activity with the esterase inhibitor quinalphos administered sublethally.

In contrast with the antagonism between (S)‐ and (R)‐α‐epimers of cypermethrin reported earlier a considerable synergism was observed between 1RtransS and 1StransR enantiomer pair on flour beetle and housefly in tarsal contact tests.

The results with stereoisomers and their mixtures were utilised in the development of two new products, Chinmix (beta‐cypermetrhin) and Transmix (theta‐cypermetrhin).     

Dissipation and sorption of six commonly used pesticides in two contrasting soils of New Zealand

We investigated dissipation and sorption of atrazine, terbuthylazine, bromacil, diazinon, hexazinone and procymidone in two contrasting New Zealand soils (0–10 cm and 40–50 cm) under controlled laboratory conditions. The six pesticides showed marked differences in their degradation rates in both top- and subsoils, and the estimated DT₅₀ values for the compounds were: 19–120 (atrazine), 10–36 (terbuthylazine), 12–46 (bromacil), 7–25 (diazinon), 8–92 (hexazinone) and 13–60 days for procymidone. Diazinon had the lowest range for DT₅₀ values, while bromacil and hexazinone gave the highest DT₅₀ values under any given condition on any soil type. Batch derived effective distribution coefficient (K _d ^eff) values for the pesticides varied markedly with bromacil and hexazinone exhibiting low sorption affinity for the soils at either depth, while diazinon gave high sorption values. Comparison of pesticide degradation in sterile and non-sterile soils suggests that microbial degradation was the major dissipation pathway for all six compounds, although little influence of abiotic degradation was noticeable for diazinon and procymidone.     

小球藻对新杀虫剂HNPC-A9908的富集与降解

HNPC-A9908[O-(3-苯氧苄基)-2-甲硫基-1-(4-氯苯基)丙基酮肟醚]是国家南方农药创制中心湖南基地研制成功的具有自主知识产权的一种新型杀虫剂.作者研究了蛋白核小球藻对HNPC-A9908的富集与降解.结果表明,蛋白核小球藻具有降解HNPC-A9908的能力,在20,100,400mg/L的浓度下,5d内HNPC-A9908的降解率分别为90.50%、66.02%和43.19%,日平均降解速率分别为3.60,13.20,34.55mg/L,其降解动力学方程可用二级反应动力学方程很好地拟合,拟合度达到83%以上.此外,蛋白核小球藻对HNPC-A9908也具有一定的富集能力,当浓度为20,100,400mg/L时达到最大富集的时间分别为24,48,48h,富集量分别为11.58,15.15,16.42mg/gFW,此后随时间的延长而逐步降低.     

Effect of cypermethrin insecticide on the microbial community in cucumber phyllosphere

Cucumber (Cucumis sativus) is one of the most widely used vegetable in the world,and different pesticides have been extensively used for controlling the insects and disease pathogens of this plant.However,little is known about how the pesticides affect the microbial community in cucumber phyllosphere.This study was the first attempt to assess the impact of pyrethroid insecticide cyperemethrin on the microbial communities of cucumber phyllosphere using biochemical and genetic approaches.Phospholipid fatty ac...     

斑马鱼群体行为变化用于水质在线预警的研究

采用计算机摄像跟踪技术,以正常水体中斑马鱼鱼群的行为变化为基础,模拟污染物突发暴露下斑马鱼鱼群游动行为(速度和高度)、通讯行为(平均距离和分散度)和区域分布(不同区域停留时间)的变化规律.结果表明:在氯氰菊酯和溴氰菊酯联合突发暴露下,斑马鱼表现出慌乱不安的过度活跃,游动速度在暴露前30 min内持续增大,变化区间由暴露前30～60 mm·s-1增至60～85 mm·s-1,而后又迅速下降至20mm·s-1左右.高度的变化稍微滞后于速度的突变,在暴露12 min后才明显增高.持续的污染物暴露和其对鱼的毒性作用也破坏了鱼群原有的通讯和分布规律,平均距离和分散度分别增大43.5%和120.0%,且鱼群在浓度相对较低、接近水面的出水口附近的停留时间明显增加.与传统的以个体鱼和单一行为反应为监测对象的方式相比,基于斑马鱼群体行为变化用于水质在线预警系统能够获得更加全面、有效的信息,是预警水质突变的可靠手段.     

杀虫剂单甲脒对绿藻的毒性研究

研究了杀虫剂单甲脒对斜生栅藻（Ｓｃｅｎｅｄｅｓｍｕｓｏｂｌｉｑｕｕｓ）和蛋白核小球藻（Ｃｈｌｏｒｅｌｌａｐｙｒｅｎｏｉ－ｄｏｓａ）的短期和长期毒性。用细胞密度计算出的４８ｈＥＣ＿（５０）分别为１．４２和１．４１ｍｇ／Ｌ，９６ｈＥＣ＿（５０）分别为１．６７和１．６２ｍｇ／Ｌ长期毒性试验结果表明，经试验初期的抑制后，杀虫剂单甲脒能促进藻类繁衍。     

一株氯氰菊酯降解真菌的筛选鉴定及其降解特性研究

从雅安市售砖茶中分离筛选出一株对氯氰菊酯具有较高降解能力的真菌菌株YAT,根据其形态学及ITS序列分析,将该菌鉴定为黑曲霉(Aspergillus niger).菌株YAT在PD培养基中168 h内对50 mg·L-1氯氰菊酯的降解率为54.83％,对氯氰菊酯的降解率与菌体生物量呈正相关.动力学研究表明,菌株YAT降解氯氰菊酯的过程符合一级动力学方程,在测试的底物(氯氰菊酯)浓度、温度、pH范围内,氯氰菊酯半衰期为85.750～281.958 h,较高温度及偏碱性条件有利于氯氰菊酯的降解,底物浓度越高,其半衰期越长.此外,菌株YAT对50 mg·L-1溴氰菊酯、氰戊菊酯、氟氯氰菊酯和氯菊酯的120 h降解率分别为27.53％、58.00％、53.23％和25.34％.     

Comparison of gas chromatography and immunoassay methods in quantifying fenitrothion residues in grape juice processed into alcoholic drinks

Abstract

Wine and Arak, the national alcoholic drink in Lebanon, were prepared from grape juice fortified with fenitrothion to a concentration of 20ppm. Samples of the 11 fractions produced by the fermentation and distillation steps were analyzed for fenitrothion residues using gas chromatography (GC) and enzyme‐linked immunosorbent assay (ELISA). Results of residue analyses showed that the two techniques were highly correlated (r = 0.978) and indicated that fenitrothion was stable during the fermentation steps but not during distillation. The clarified wine 35 days later contained about 85% (15.3 ppm) of the fenitrothion concentration found in the juice as determined by GC analysis. Arak was prepared by a two‐steps distillation of the clarified wine. The alcohol distillate and undistilled fraction from the first distillation contained 2.5 ppm and 5.8 ppm of fenitrothion, respectively. No fenitrothion residues were detected by both techniques in the four fractions collected from the second distillation step.     

83—1除草剂和速杀威杀虫剂的小鼠耳肿致敏试验

本文采用较新的致敏性检测方法小鼠耳肿实验对８３—１除草剂和纯中药杀虫剂速杀威进行了检测。实验共设６个组，包括：速杀威原液，１０％速杀威，０．１６％８３—１，０．３２％８３—１及阴性和阳性对照组。结果显示４个受试物组在致敏后２４小时和４８小时均未观察到致敏作用，说明该受试物在此条件下不具致敏性，同时也验证了小鼠耳肿试验用于有色受试物检测致敏性的优越性。