Volatile analogues of penconazole and their activity against the take-all fungus,Gaeumannomyces graminis var. tritici

Eight new sterol biosynthesis-inhibiting fungicides, structurally related to penconazole and having vapour pressures up to 118 mPa, were synthesised. Their toxicities to the cereal take-all fungus, Gaeumannomyces graminis var. tritici, on agar were measured; intrinsic activities were measured after incorporating the compounds into the agar and vapour activities were measured after their evaporation from glass and from moist soil. Vapour activity following evaporation from soil was shown to be a function of both the intrinsic activity of the compound and its partition coefficient between the air and moist soil (K_as). The latter is itself a function of vapour pressure, 1-octanol/water partition coefficient (K_ow) and the soil type. The compound most active as vapour from soil in the in-vitro test, 1-(pyridin-3-yl)-2-(4-flurorophenyl)pentane, was ineffective against take-all in wheat in a pot test in which the inoculated soil was treated unevenly, providing further evidence that the redistribution of fungicides in moist soil occurs predominantly via the water phase rather than the vapour phase.     

Water balance,respiration and immobilisation in relation to deltamethrin poisoning and physical conditions in the epigeal spider Oedothorax apicatus

The effect of a pyrethroid insecticide, deltamethrin, on water loss, metabolic rate and immobilisation was studied, using the epigeal spider Oedothorax apicatus (Blackwall) (Linyphiidae) as a test species. Water loss was measured gravimetrically at different temperatures, air humidities, and doses of deltamethrin. Metabolic rate and immobilisation were measured at different temperatures and doses. Immobilisation was measured at different relative humidities and temperatures. Water loss due to evaporation increased linearly with vapour pressure deficit. The slope of the latter relationship increased with temperature, indicating an increase in cuticle permeability with temperature. In addition to water loss by evaporation, deltamethrin treatment induced water excretion. This was positively related to dose and temperature, but independent of air humidity. Metabolic rate increased with temperature and dose. Immobilisation was highest at low temperatures in combination with low air humidity. The consequences of pesticide-induced water excretion are discussed with respect to field- and laboratory-based dose-effect relationships for pyrethroids presented in the literature. The present results seem to offer an explanation for hitherto unexplained minima in temperature-response curves in pyrethroid toxicity in some arthropod species. It is concluded that simultaneous measurements of metabolic rate, water-loss rate and pesticide effects are a prerequisite for an understanding of the effects of pesticides on arthropods.     

基于介孔二氧化硅的鱼藤酮纳米颗粒的制备及其性能研究

纳米材料作为农药载体可提高农药稳定性和调控农药释放速率,是提高农药利用率的重要手段。介孔二氧化硅纳米粒子 (MSNs) 是一种具高比表面积、粒径与孔径可调节和生物相容性良好的纳米载体。鱼藤酮是非内吸性植物源杀虫剂,在环境中易降解。本研究先通过改良的软模板法制备出粒径均一的MSNs,再通过溶剂挥发法将鱼藤酮负载到MSNs中,制备得到载鱼藤酮MSNs (Rot@MSNs),其载药率达31.6%,具有良好的缓释特性,缓释时间可达288 h以上;施药处理3 d后在番茄的上部叶片和下部叶片中均检测到了鱼藤酮,表明纳米载体MSNs提高了鱼藤酮在番茄植株中的内吸和传导能力。该研究对于减少农药使用量、降低环境污染等具有重要意义。     

七种农药在3种不同类型土壤中的吸附及淋溶特性

采用振荡平衡法和土柱淋溶法研究了2,4-滴酸、丁噻隆、毒草胺、炔草酸、氟环唑、甲基磺草酮和烯啶虫胺7种农药在江西红壤、太湖水稻土及东北黑土3种不同理化性质土壤中的吸附及淋溶特性,探讨了农药性质及土壤理化性质对供试农药在土壤中吸附、淋溶行为的影响。结果表明:农药的水溶性越大,其在土壤中的吸附性越弱,淋溶性越强;农药在土壤中的吸附性与土壤pH值、有机质含量以及阳离子交换量之间有较好的相关性。土壤pH值、有机质含量以及农药性质是影响农药在土壤中淋溶及迁移的主要因素。     

A novel chitosan-poly(lactide) copolymer and its submicron particles as imidacloprid carriers

BACKGROUND: The aim of the present work was to synthesise novel amphiphilic chitosan–co‐(D,L‐lactide) (chitosan–PLA) copolymers and to study the formation of pesticide‐loaded polymeric submicron particles. These copolymeric submicron particle systems are expected to be potential candidates for applications in pesticide delivery. RESULTS: The chemical structures of the copolymers were confirmed by Fourier transform infrared spectroscopy (FT‐IR), ¹H nuclear magnetic resonance (¹H NMR) and thermogravimetric analysis (TGA). Imidacloprid as a lipophilic model pesticide can be incorporated into chitosan–PLA submicron particles by nanoprecipitation and the emulsion/solvent evaporation method. Size, the size distribution, the imidacloprid loading content (LC) and the imidacloprid release behaviour were investigated. CONCLUSION: Conjugation of PLA to chitosan was shown to be an available method for the preparation of submicron particles for lipophilic pesticide delivery. The imidacloprid‐loaded submicron particles showed a sustained release process. As the mass ratio of copolymer to imidacloprid increased, the submicron particles size and LC decreased. The chitosan–PLA submicron particles could be useful as pesticide carriers for imidacloprid delivery systems. Copyright © 2011 Society of Chemical Industry     

植物油助剂Aero-mate 320对植保无人机稻田低容量喷雾沉积利用率的提升效果及其机理分析

为明确添加植物油助剂Aero-mate 320对植保无人机施药体系的影响,评价其作为航空喷雾助剂的可行性,通过在15%甲维·茚虫威悬浮剂和325 g/L苯甲·嘧菌酯悬浮剂药液中添加0.3%、0.6%和1.0%的Aero-mate 320,测定并评估其对药液体系理化性质、抗蒸发性以及雾滴在水稻田沉积分布和沉积利用率的影响。结果表明,助剂Aero-mate 320的适量添加可以改善药液的理化性质,提高喷雾的均匀性,减少蒸发,增加雾滴在水稻冠层的覆盖及沉积,并能显著增加农药沉积利用率。其中,添加0.6% Aero-mate 320后药液的表面张力以及在水稻叶片上的接触角显著减小,分别降低13.3%和30.3%,黏附张力由-9.7 mN/m增加至9.1 mN/m,黏附功增加51.3%,药液更易润湿叶片;雾滴粒径显著增大,雾滴谱相对跨度显著变窄,雾滴分布更加均匀,小雾滴数量显著降低,减少了雾滴的飘移;对喷雾雾滴蒸发的抑制率为25.0%;同时药液在水稻冠层中的沉积密度和覆盖率增大,沉积量显著增加,农药沉积利用率增至66.8%。     

嘧菌酯·苯醚甲环唑PBS/PLA微球的结构表征与释放性能

以PBS/PLA共混物为复合载体,嘧菌酯和苯醚甲环唑为包埋有效成分,聚乙烯醇(PVA-1788)为分散剂,采用溶剂挥发法制备了嘧菌酯·苯醚甲环唑PBS/PLA微球。通过光学显微镜、扫描电子显微镜、Nicolet 6700型傅立叶变换红外光谱仪、高效液相色谱(HPLC)等表征复配农药微球的性质,采用透析袋法测定其缓释性能。结果表明,所得的嘧菌酯·苯醚甲环唑PBS/PLA微球中嘧菌酯的载药量和包埋率分别为14.30%、85.06%,苯醚甲环唑的载药量和包埋率为9.47%、90.18%,且微球球形规整,平均粒径为7.20μm。嘧菌酯·苯醚甲环唑PBS/PLA微球具有良好的缓释性能,并且2种活性成分的释放量之比与其最佳复配比接近,可以达到增效目的。     

Determination of the vapour pressure of pesticides

An instrument for measuring the vapour pressures of pesticides has been constructed using a suitably adapted gas chromatographic oven. Using this apparatus and a method involving gas saturation, followed by chromatographic analysis of the trapped pesticide vapour, the vapour pressures of a number of pesticides and non-pesticides have been determined. It has been demonstrated that this procedure gives repeatable and accurate values by statistical comparison of the results obtained with data abstracted from the literature.     

负载咪鲜胺介孔二氧化硅粒子的制备及性能与安全性评价

介孔二氧化硅粒子(MSNs)可作为载体用于制备高载药量的农药缓控释剂,从而实现农药减量化使用和生态环境保护的目的。本研究采用“一锅法”制备了负载咪鲜胺的介孔二氧化硅载药粒子(prochloraz@MSNs),并对其外观形貌、载药量、释放行为、抑菌作用以及对非靶标生物的安全性进行了系统研究。结果表明：所制备的prochloraz@MSNs呈规则球形,粒径均匀,平均粒径约240 nm,载药量为40.6%,释放速率与pH值和温度相关,酸性、碱性及高温条件均有利于其中咪鲜胺的释放。与常规制剂咪鲜胺乳油相比,prochloraz@MSNs对稻瘟病菌和小麦赤霉病菌的抑制效果更好,持效期更长;对斑马鱼、蚯蚓和人体肺部BEAS-2B细胞的毒性较低。因此,prochloraz@MSNs作为一种高效、低毒、安全的农药新剂型,在植物病害的可持续治理中将具有很好的发展潜力。     

三种拟除虫菊酯类农药在砂土和壤土中的淋溶行为

采用土柱淋溶法和气相色谱法研究了3种拟除虫菊酯类农药三氟氯氰菊酯、联苯菊酯和高效氯氰菊酯在热带地区主要土壤类型砂土和壤土中的淋溶特性。结果表明:3种拟除虫菊酯类农药在砂土和壤土中主要残留于第1段土壤 (0～5 cm) 中,且驻留量随土壤深度增大而减少。三氟氯氰菊酯、高效氯氰菊酯和联苯菊酯在砂土中的R_i值分别为52.86%、94.73%和83.19%,在壤土中的R_i值分别为54.70%、77.28%和55.33%,均大于50%。根据农药在土壤中的淋溶性等级划分标准,3种药剂均属于难淋溶农药,不易对地下水造成污染。本研究结果可为热带地区土壤和地下水中农药污染修复提供参考。     

A method for determining the volatility of active ingredients used in plant protection

The paper describes a gravimetric method of determining the volatility (evaporation rate) of pesticides. The measuring apparatus may be set at any temperature between ～15 and 80°C; the dry air flowing through the apparatus is regulated by valves between -0.2 1/h and 300 1/h. Figures available for vapour pressure reveal a mathematical relation between vapour pressure and evaporation rate. This can be used as a simple method of determining the vapour pressure of any substance at 20°C by determining the evaporation rate when the air current is flowing at 50 l/h. The effects of the temperature and the air flow rate on the evaporation rate are also analysed.     

Influence of pesticides on the activity and kinetics of invertase,urease and acid phosphatase enzymes

The effects of four pesticides (three herbicides, atrazine, paraquat, glyphosate, and an insecticide, carbaryl) on the activity and kinetics of an invertase (from yeast), a urease (from jack bean) and an acid phosphatase (from potato) were investigated. Glyphosate and paraquat showed a marked activation effect on invertase activity. From the dependence of V_max and K_m parameters on pesticide concentrations, a mixed-type activation mechanism was suggested. The kinetic behaviour of urease and acid phosphatase appeared to be uninfluenced by both pesticides. Methanol, used as solvent for both carbaryl and atrazine, inhibited invertase, urease and acid phosphatase with, respectively, competitive, non-competitive and uncompetitive mechanisms. The extent of the inhibition was different, as estimated by the values of the inhibition constant K₁. An additional inhibition effect of urease and invertase activities was achieved in the presence of carbaryl, whereas no influence was detected on the activity and kinetics of acid phosphatase. Finally, atrazine was shown to alter the kinetics of the enzymes only at higher concentrations.     

五种加工方式对黄瓜中10种农药残留的去除效果

在实验室模拟沉积农药条件下,通过液相色谱-串联质谱 (LC-MS/MS) 和气相色谱-串联质谱 (GC-MS/MS) 检测技术,研究了经水洗、水煮、炒制、去皮和腌制5种加工方式后,多菌灵、吡虫啉、啶虫脒、乙霉威、霜霉威、丙溴磷、氯氰菊酯、三唑磷、敌敌畏和嘧霉胺10种农药在黄瓜中的残留量变化情况。结果表明:在5种加工方式中,以去皮处理对农药的去除效果最明显,其中丙溴磷和氯氰菊酯的加工因子 (PF) 均为0.04,其他4种加工方式对农药去除效果的强弱顺序为水煮>炒制、水洗、腌制;农药的log K_ow(辛醇水分配系数) 值跟农药的去除效果直接相关,经水洗和水煮2种加工方式处理后,农药的log K_ow值越小,越易被去除。另外,水洗、水煮和炒制处理,在0~10 min内随处理时间延长农药残留量呈减小的趋势,10种农药的PF变化范围为:水洗时PF在1.00~0.62之间,水煮时PF在0.86~0.37之间,炒制时PF在1.13~0.52之间。     

载药明胶微球剂的制备及应用研究进展

微球剂(microspheres)是指活性成分溶解或均匀分散在辅料(包括载体)中形成的微小球状实体(粒径一般在1～250μm之间).天然高分子明胶因具有无毒无害、来源丰富、生物可降解等特点已成为控释剂的理想载体,在生物、医学及农药等领域展现出良好的应用前景.本文重点论述了以明胶为载体,负载农药(医药)后形成微球剂的制备...     

Factors affecting residues of pesticides in tea

This paper presents a discussion on residue behaviour of 17 pesticides on tea, on the basis of the research conducted during the last 20 years. Sunlight photolysis and growth dilution were the most important factors affecting pesticide persistence in the growing tea plant, while vapour pressure played an important role in loss of pesticide residues during tea processing. The percentage of pesticide extracted during the tea infusion process was highly related to water solubility. It is suggested that in studies on pesticide residue behaviour on tea, all the four factors should be considered integrally.     

浅谈溶剂蒸发法制备微胶囊与农药微胶囊的开发

简要介绍了微胶囊技术的研究进展,重点综述了溶剂蒸发法制备微胶囊的技术特点及其影响因素,分析了目前农药微胶囊制剂的发展概况及存在的问题,展望了溶剂蒸发法在农药微胶囊制备中的应用前景。     

Current- and past-use pesticide prevalence in drainage ditches in the Lower Mississippi Alluvial Valley

BACKGROUND: Pesticide application is common in agriculture and often results in applied pesticides entering adjacent aquatic systems. This study seasonally analyzed a suite of 17 current‐ and past‐use pesticides in both drainage waters and sediments to evaluate the prevalence of pesticides in drainage ditches across the Lower Mississippi Alluvial Valley (LMAV). RESULTS: There were significantly higher concentrations (P < 0.05) of current‐use than past‐use pesticides; however, there were consistently high numbers of detections of past‐use pesticides in sediments. Sediment pesticide concentrations were an order of magnitude higher (150–1035 µg kg^?1) than water samples (6–20.9 µg L^?1). Overall, 87% of all samples analyzed for current‐ and past‐use pesticides were non‐detects. p,p′‐DDT was detected in 47.5% of all drainage waters and sediments sampled. There were significant correlations (0.372 ≥ r²≤0.935) between detected current‐use water and sediment concentrations, but no significant correlations between past‐use water and sediment concentrations. CONCLUSION: Overall, there was a high percentage (87%) of sediment and water samples that did not contain detectable concentrations above the lower limit of analytical detection for each respective pesticide. This lack of pesticide prevalence highlights the improved conditions in aquatic systems adjacent to agriculture and a potential decrease in toxicity associated with pesticides in agricultural landscapes in the LMAV. Copyright © 2011 Society of Chemical Industry     

Movement of pesticides to surface waters from a heavy clay soil

A field experiment at Cockle Park, Northumberland on a clay loam soil (Dunkeswick series) cropped with winter wheat investigated the effects of drainage and season of application on pesticide movement. Isoproturon, mecoprop, fonofos and trifluralin were applied in two consecutive seasons at normal agricultural rates to three hydrologically isolated plots each of 0.25 ha. Two of the plots were mole-drained and the third was an undrained control. Surfacelayer flow and drainflow from each plot were monitored at 10-min intervals. Samples of flow were analysed for pesticides to evaluate transport of applied chemicals from the site. Despite widely differing properties (K_oc 20–8000 ml g^?1, t_1/2 10–60 days), all four pesticides were found in surface-layer flow and mole drainflow from the site. Maximum concentrations of pesticides in flow ranged from 0.1 to 121 μg litre^?1 (aqueous phase) and < 0.2 to 48 μg litre^?1 (particulate phase). Over two contrasting seasons, total losses of pesticides in flow followed total amounts of flow and were approximately four and five times larger, respectively, in 1990/91 than in 1989/90. The maximum loss occurred from the undrained plot and was 2.8 g isoproturon (0.45% of that applied). Total losses of autumn-applied pesticides from an undrained plot were up to four times greater than losses from a mole-drained plot. Mole drainage decreased movement of pesticides from this slowly permeable soil by reducing the amount of surfacelayer flow. Maximum concentrations of mecoprop and isoproturon in drainflow were 10–20 times larger following spring application than after application in autumn. Bypass flow down soil cracks was an important process by which pesticide was lost from the site, with transport to the drainage system via mole channels (55 cm depth) after less than 0.5 and 6.7 mm net drainage in the two winters.     

Rate of volatilisation of pesticides from soil surfaces; comparison of calculated results with those determined in a laboratory model system

A laboratory model system for the determination of the volatility of non-ionic pesticides from soil surfaces is presented. The pesticides examined were the insecticides methidathion, diazinon, and isazophos, the herbicide metolachlor, and the fungicide metalaxyl. The rates of volatilisation of these compounds from soil increased with increasing pesticide concentration, temperature and air flow rate and with decreasing soil organic matter content. The volatilities of the same pesticides were also calculated by using their vapour pressure, water solubility and soil adsorption data. The excellent correlation between calculated and experimental results showed that information on the volatility of a chemical can be obtained simply by calculation. Such calculations allow the classification of each pesticide according to its volatility, and therefore represent a useful alternative for volatility studies in laboratory model systems.