六种新烟碱类杀虫剂残留在苹果实验室模拟加工中的变化

为明确苹果中残留的烯啶虫胺、噻虫嗪、吡虫啉、噻虫胺、呋虫胺和啶虫脒6种新烟碱类药剂在不同加工过程中的变化情况,采用高效液相色谱法研究了6种药剂在苹果实验室罐头、果酱、果酒和果醋模拟加工过程中的残留量变化。结果表明:在苹果罐头加工过程中,6种药剂在罐头中残留量与初始浓度相比均显著降低,其中吡虫啉和噻虫胺在罐头中的加工因子较高,均为0.8,啶虫脒在罐头中的加工因子最低,为0.1。罐头汁中烯啶虫胺的加工因子最高,为0.5,其次为啶虫脒和噻虫嗪,均为0.4。在果酱加工过程中,烯啶虫胺、噻虫嗪、吡虫啉、噻虫胺、呋虫胺和啶虫脒的加工因子分别为0.8、0.9、0.9、1.0、0.9和0.9。在果酒中除吡虫啉的加工因子为0.1外,其余药剂加工因子均小于0.1。在果醋中除噻虫胺有少量残留(0.05 mg/kg)外,其余药剂均低于检出限。6种新烟碱类药剂在苹果实验室模拟加工过程中,加工因子均小于1,残留降低。     

超高效液相色谱-串联质谱法测定豇豆中溴氰虫酰胺等5种农药残留

建立了超高效液相色谱-串联质谱(UPLC-MS/MS)同时测定豇豆中溴氰虫酰胺、乙基多杀菌素、呋虫胺、噻虫嗪和啶虫脒残留量的方法。豇豆样品经乙腈提取,通过QuEChERS法净化后,采用Acquity UPLCBEH C18色谱柱分离,在电喷雾正离子模式下以多反应监测(MRM)模式检测。结果表明:在0.01~1μg/mL内5种农药的峰面积与其相应的质量浓度间呈良好线性关系,相关系数均大于0.99;在0.01、0.1和1 mg/kg 3个添加水平下,回收率为71%~129%,相对标准偏差为0.90%~20.8%(n=5)。5种农药在豇豆中的检出限为0.084~4.0μg/kg,定量限为0.80~16.6μg/kg。该方法简单灵敏,定量准确,可用于分析豇豆中的溴氰虫酰胺、乙基多杀菌素、呋虫胺、噻虫嗪和啶虫脒的残留量。     

新烟碱类杀虫剂种子包衣防治麦蚜的可行性评价

为评价不同新烟碱类杀虫剂处理种子防治小麦蚜虫的应用潜力,采用种子包衣法分别在室内及田间比较了吡虫啉、噻虫嗪、啶虫脒、烯啶虫胺、噻虫啉防治小麦蚜虫的效果及安全性,并测定了吡虫啉和噻虫嗪的持效、对天敌和小麦产量的影响及其在小麦籽粒中的最终残留量。结果表明,在2.4、3.6和4.8 g/kg种子剂量下,啶虫脒明显降低小麦出苗率,而其它药剂均无显著影响;至抽穗前烯啶虫胺、啶虫脒和噻虫啉对麦蚜的防效低,吡虫啉和噻虫嗪则均有较高防效,在58.17%以上,而在小麦抽穗扬花期防效下降,为33.57%~60.46%。吡虫啉和噻虫嗪对叶部麦蚜防效均相应高于穗部。与喷雾处理相比,吡虫啉、噻虫嗪各剂量种子包衣对瓢虫和蚜茧蜂等天敌昆虫影响小,在3.6、4.8 g/kg种子剂量下,小麦千粒重和产量无显著差异,且在小麦籽粒中的残留量低。表明吡虫啉和噻虫嗪种子包衣防治麦蚜的应用潜力大。     

QuEChERS-高效液相色谱-串联质谱法测定榛子中4种农药的残留

建立了同时检测榛子中苯醚甲环唑、丙环唑、噻虫嗪和啶虫脒4种农药残留量的QuEChERS-高效液相色谱-串联质谱 (HPLC-MS/MS) 检测方法。榛仁和榛壳分别经正己烷饱和的乙腈和乙腈提取,用弗罗里硅土、石墨化碳黑 (GCB) 和N-丙基乙二胺 (PSA) 净化。C₁₈色谱柱分离,采用电喷雾正离子 (ESI+) 扫描,在多重反应监测 (MRM) 模式下进行质谱分析,外标法定量。结果表明:在0.01～2 mg/kg范围内,苯醚甲环唑、丙环唑、噻虫嗪和啶虫脒4种供试农药的质量浓度与对应的峰面积间呈良好线性关系 (R2 > 0.990 2)。在0.01、0.1和1 mg/kg 3个添加水平下,4 种农药在榛子中的日内平均回收率为79%～111%,相对标准偏差 (RSDs) (n = 5) 为0.6%～6.9%,日间平均回收率为81%～110%,RSDs (n = 15) 为1.1%～8.5%。4种农药的定量限均为0.01 mg/kg。此方法简单、高效,可为榛子等坚果类食品中多种农药残留的同时测定提供参考。     

基质固相分散-高效液相色谱法测定小麦籽粒中吡虫啉和啶虫脒残留

建立了以C18键合硅胶作为固相分散剂,高效液相色谱法同时测定小麦籽粒中吡虫啉和啶虫脒残留的分析方法。C18键合硅胶与样品一起研磨均匀制成基质固相分散柱,用乙腈淋洗,浓缩后用高效液相色谱检测。结果表明:吡虫啉在0.05~0.8 mg/L、啶虫脒在0.1~1.0 mg/L的范围内线性良好,相关系数分别为0.999 6、0.999 7。在0.05、0.1、0.5 mg/kg水平时,吡虫啉和啶虫脒的添加回收率分别在88.5%~98.4%和93.2%~98.9%之间,相对标准偏差分别在2.0%~3.8%和3.6%~9.8%之间,仪器最低检出量分别为0.1 ng和0.4 ng,方法最小检出浓度分别为0.04 mg/kg 和 0.1 mg/kg。该方法简便、快速、溶剂消耗少,满足农药残留分析的要求。     

啶虫脒金标免疫速测试纸条研制及其在茶叶中的应用

阐述了一种基于直接竞争免疫层析法的啶虫脒金标速测试纸条的研制方法,及其在茶叶中快速检测与诊断啶虫脒残留的应用情况。通过制备啶虫脒人工抗原,获得了高灵敏度的单克隆抗体,抗体效价大于1:10000。据此研制的金标速测试纸条对啶虫脒肉眼判断的检出限为10ng/mL,检测时间为10min;可特异性地检测茶叶(绿茶、红茶、铁观音)中烟碱类农药啶虫脒的残留量,而对其他烟碱类农药(吡虫啉、噻虫嗪、烯啶虫胺等)无交叉反应,能满足中国茶叶中啶虫脒最大残留限量(0.5mg/kg)下的检测要求,具有灵敏度高、使用便捷、结果准确、成本低等优点。该技术可以实现成品茶样品中啶虫脒的现场快速测试诊断。     

叶菜中三种新烟碱类农药的残留吸附动力学和复合效应初探

采用乙腈提取,QuEChERS方法净化,超高压液相色谱仪检测的方法,动态监测3种新烟碱类农药单一及混合使用后青菜中吡虫啉、啶虫脒及噻虫嗪的残留量变化,并进行吸附动力学分析。结果表明,青菜中3种农药的残留量随时间延长增加,不同处理组分别在24~48h达到残留量最高值,之后残留量缓慢降低并趋于稳定。经卡方检验分析,3种农药在青菜中的吸附行为更符合准一级动力学模型,且决定系数R2大部分大于0.9。3种农药混合使用时存在相互作用,相较于农药的单独使用,混用能够提高各自在青菜中的吸附速率。吡虫啉与啶虫脒之间存在相互促进作用,混合使用后各自的残留量和峰值均提高。但两者与噻虫嗪存在抑制作用,混用后青菜中噻虫嗪的最高残留量降低。该研究为农药复合残留风险评估和田间混合施药提供了基础数据。     

噻虫嗪及其代谢物噻虫胺在节瓜中的消解动态及初步膳食风险评估

为明确噻虫嗪在节瓜上的残留行为,于2015年在广东和上海两地进行了噻虫嗪在节瓜上的规范田间残留试验,建立了节瓜中噻虫嗪及其代谢物噻虫胺残留量的高效液相色谱-串联质谱 (HPLC-MS/MS) 检测方法。样品用乙腈提取,经氨基固相萃取小柱净化,HPLC-MS/MS 检测,外标法定量。结果表明:噻虫嗪在节瓜上的消解半衰期为4.98~5.84 d;采用25%噻虫嗪水分散粒剂 (WG),分别按有效成分75和112.5 g/hm2 的剂量于幼果期开始施药,施药2~3次,每次施药间隔期为7~10 d,距最后一次施药后3、5、7 d 采样测定,节瓜中噻虫嗪和噻虫胺的残留量分别为0.010~0.422 mg/kg和 <0.010~0.020 mg/kg。膳食摄入风险初步评估结果显示:其风险商值 (RQ) 为0.044,表明噻虫嗪的长期膳食摄入风险较低。目前中国尚未制定噻虫嗪在节瓜上的最大允许残留限量 (MRL) 标准,根据试验结果,建议中国可将噻虫嗪在节瓜上的MRL值暂定为1 mg/kg。     

巴西重新评价烟碱类农药

巴西生态管理部门启动蜜蜂高风险农药的再评价项目,环境局(IBAMA)将从拜耳的吡虫啉入手,开展噻虫嗪、噻虫啉、啶虫脒等烟碱类杀虫剂的再评价,相关细节已在当月政府公告中公布。在巴西吡虫啉较其它三种烟碱类产品销量     

高效液相色谱-质谱联用法测定白芍药材中23种农药残留

采用高效液相色谱-质谱联用法(HPLC-MS)定量检测了白芍药材中的23种农药残留,样品经乙腈提取后再用PSA(N-丙基乙二胺)进行分散固相萃取。方法的定量限(LOQ)为0.75~12.17 μ g/kg;在0.01和0.1 mg/kg两种添加水平下,除极性较大的噻虫嗪和吡虫啉外,其余农药的回收率均在70%~120%之间,相对标准偏差(RSD) 在2.8%~18.9%之间。该方法净化效果好、灵敏度高、重现性好,可用于白芍样品中农药残留的日常检测。     

Soil microbial degradation of neonicotinoid insecticides imidacloprid, acetamiprid, thiacloprid and imidaclothiz and its effect on the persistence of bioefficacy against horsebean aphid Aphis craccivora Koch after soil application

BACKGROUND: The neonicotinoids imidacloprid, imidaclothiz, acetamiprid and thiacloprid consist of similar structural substituents but differ considerably with respect to soil use. Therefore, the effects of soil microbial activity on the degradation and bioefficacy persistence of the four neonicotinoids were evaluated. RESULTS: In unsterilised soils, 94.0% of acetamiprid and 98.8% of thiacloprid were degraded within 15 days, while only 22.5% of imidacloprid and 25.1% of imidaclothiz were degraded over a longer period of 25 days. In contrast, in sterilised soils, the degradation rates of acetamiprid and thiacloprid were respectively only 21.4% and 27.6%, whereas the degradation rates of imidaclothiz and imidacloprid were respectively 9.0% and almost 0% within 25 days. The degradation products of imidacloprid and imidaclothiz were identified as olefin, nitroso or guanidine metabolites, the degradation product of thiacloprid was identified as an amide metabolite and no degradation product of acetamiprid was detected. A bioefficacy assay revealed that the bioefficacy and persistence of imidacloprid, imidaclothiz, acetamiprid and thiacloprid against horsebean aphid A. craccivora were related to their degradation rate and the bioefficacy of their degradation products in soil. CONCLUSION: Soil microbial activity played a key role in the bioefficacy persistence of neonicotinoid insecticides and therefore significantly affected their technical profile after soil application. Copyright © 2011 Society of Chemical Industry     

七种新烟碱类杀虫剂对韭菜迟眼蕈蚊幼虫及蚯蚓的选择毒力

为筛选出高效安全的韭蛆防治药剂,室内采用胃毒触杀联合毒力法比较了吡虫啉、啶虫脒、噻虫嗪、噻虫胺、呋虫胺、烯啶虫胺、噻虫啉与毒死蜱和高效氯氟氰菊酯等6种对照药剂对韭菜迟眼蕈蚊幼虫的毒力,同时用人工土壤法测定了13种药剂对蚯蚓的急性毒性,并通过盆栽试验验证了其对韭蛆和蚯蚓的选择毒力。结果表明,吡虫啉、噻虫胺、呋虫胺、噻虫啉、噻虫嗪对韭菜迟眼蕈蚊4龄幼虫的毒力明显高于6种对照药剂,对虫酰肼的相对毒力倍数分别为101.6、55.0、32.9、27.2、13.6;13种供试药剂中,除吡虫啉、啶虫脒、噻虫胺、呋虫胺对蚯蚓中等毒性外,其余均为低毒;盆栽试验中,吡虫啉、噻虫嗪、毒死蜱、噻唑膦、高效氯氟氰菊酯的防虫效果和保苗效果均分别高于其它药剂,但其中只有噻虫嗪对蚯蚓没有明显致死作用。     

基于推荐用量分析我国新烟碱类杀虫剂的登记现状

本文对目前中国农药信息网上公布登记的吡虫啉、烯啶虫胺、啶虫脒、噻虫啉、噻虫嗪、噻虫胺、呋虫胺、氯噻啉、哌虫啶、环氧虫啶等10种新烟碱类杀虫剂的信息进行了查询,分别从登记剂型、作物、防治靶标等方面对这10种杀虫剂的登记推荐有效成分用量情况进行了统计分析,最后,挑选用量范围最大的3种有效成分,5种作物,5种靶标进行组合,并对可能的18种组合进行了数据分析。结果发现:1)在防治草坪-蛴螬和甘蔗-蔗螟上,吡虫啉的有效成分用量要明显高于噻虫嗪和噻虫胺两种药剂,最高分别为2 100.00和1 500.00 g/hm~2;2)在防治韭菜-韭蛆上,噻虫嗪的有效成分用量要明显高于吡虫啉和噻虫胺,最高为1 732.50 g/hm~2;3)在防治小麦-蚜虫方面,吡虫啉的推荐有效成分用量范围最大(相差120倍),且偏高数值点最多;4)在防治水稻-飞虱上,同样是吡虫啉的偏高数值点最多。为减少农药施用,建议在病虫防治时推荐应用有效成分用量较低的农药类型(包括推荐有效成分用量更低的农药剂型和生物活性更高的农药有效成分)。未来农药登记用量将在农药最低有效剂量研究的基础上,针对不同药剂在不同作物的特定防治靶标提出更加科学、合理的推荐用量,为我国农药的合理减施提供科学依据。     

Comparative analysis of neonicotinoid binding to insect membranes: I. A structure-activity study of the mode of [3H]imidacloprid displacement in Myzus persicae and Aphis craccivora

Neonicotinoids bind selectively to insect nicotinic acetylcholine receptors with nanomolar affinity to act as potent insecticides. While the members of the neonicotinoid class have many structural features in common, it is not known whether they also share the same mode of binding to the target receptor. Previous competition studies with [3H]imidacloprid, the first commercialised neonicotinoid, indicated that thiamethoxam, representing a novel structural sub-class, may bind in a different way from that of other neonicotinoids. In the present work we analysed the mode of [3H]imidacloprid displacement by established neonicotinoids and newly synthesized analogues in the aphids Myzus persicae Sulzer and Aphis craccivora Koch. We found two classes of neonicotinoids with distinct modes of interference with [3H]imidacloprid, described as direct competitive inhibition and non-competitive inhibition, respectively. Competitive neonicotinoids were acetamiprid, nitenpyram, thiacloprid, clothianidin and nithiazine, whereas thiamethoxam and the N-methyl analogues of imidacloprid and clothianidin showed non-competitive inhibition. The chloropyridine or chlorothiazole heterocycles, the polar pharmacophore parts, such as nitroimino, cyanoimino and nitromethylene, and the cyclic or acyclic structure of the pharmacophore were not relevant for the mode of inhibition. Consensus structural features of the neonicotinoids were defined for the two mechanisms of interaction with [3H]imidacloprid binding. Furthermore, two sub-classes of non-competitive inhibitors can be discriminated on the basis of their Hill coefficients for imidacloprid displacement. We conclude from the present data that the direct competitors share the binding site with imidacloprid, whereas non-competitive compounds, like thiamethoxam, bind to a different site or in a different mode.     

香蕉中农药多残留分析及短期膳食摄入风险评估

为掌握我国香蕉中农药残留情况及其短期膳食摄入风险,测定了采自香蕉主产省份生产基地及市场的196份香蕉样品中的农药残留,评估了所检出农药对我国成人和1～～6岁儿童的短期膳食摄入风险.结果表明:香蕉全果中咪鲜胺(42.86％)、吡唑醚菌酯(40.82％)、吡虫啉(34.69％)及多菌灵(27.55％)的检出率较高;就农药类...     

温度、光照及生物因子对啶虫脒和吡虫啉在 油菜叶面消解的影响

采用室内模拟方法研究了啶虫脒、吡虫啉在温度、光照和生物因子作用下在油菜叶面的消解趋势。结果表明:在14、25、35℃下啶虫脒在油菜叶面消解的半衰期分别为19.3、6.6和5.2 d,同一条件下吡虫啉的消解半衰期分别为8.7、3.8和2.9 d, 两者的消解速度均随温度升高而加快,但消解趋势有所不同;在光照强度为500、3 000、6 000 lx条件下,啶虫脒的消解半衰期分别为19.1、10.4 和6.6 d,吡虫啉的消解半衰期分别为6.9、6.2和3.7 d,两者消解速度均随光强的增加而加快,但光强变化对啶虫脒消解影响更为明显。25℃时,自然叶面、消毒处理叶面啶虫脒消解半衰期分别为6.6 和 8.1 d,吡虫啉为3.8和3.5 d,表明叶面微生物稍加快了啶虫脒的消解,而对吡虫啉的消解影响不显著。     

Thiamethoxam acts as a target‐site synergist of spinosad in resistant strains of Frankliniella occidentalis

BACKGROUND: Previous studies have suggested that the resistance mechanism towards spinosad in Frankliniella occidentalis (Pergande) is an altered target site. Like the neonicotinoids, the spinosyns act on nicotinic acetylcholine receptors (nAChRs) in insects, but at a distinct site. The changes in nAChRs related to spinosad resistance in thrips might involve interaction with neonicotinoids. In this study, the efficacy of spinosad and neonicotinoids, alone and in combination, was evaluated in susceptible and spinosad‐resistant thrips strains. RESULTS: The neonicotinoids tested were imidacloprid, thiacloprid, acetamiprid, thiamethoxam and clothianidin. No cross‐resistance was shown between spinosad and any of the neonicotinoids. However, an increased toxicity was observed when a mixture of spinosad with thiamethoxam or clothianidin was tested. No synergism was found in the susceptible strains. The more spinosad‐resistant the thrips strain, the stronger was the synergism. CONCLUSION: Data suggest that spinosad and thiamethoxam may interact at the nAChRs in spinosad‐resistant thrips, facilitating enhanced insecticidal action. Copyright © 2012 Society of Chemical Industry     

Resistance and cross-resistance to neonicotinoid insecticides and spinosad in the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae)

The Colorado potato beetle, Leptinotarsa decemlineata (Say), has developed resistance to many insecticides used for its control, recently including imidacloprid, a neonicotinoid compound. Other neonicotinoids are now being deployed to control this pest. A key point in the strategies of resistance management is the monitoring of resistance and cross-resistance. In the summer of 2003, imidacloprid-resistant adult Colorado potato beetles collected from Long Island, New York, USA were bioassayed using topical applications of imidacloprid and nine other neonicotinoids. Compared to a standard susceptible strain, the Long Island beetles showed 309-fold resistance to imidacloprid, and lower levels of cross-resistance to all other neonicotinoids, despite these never having been used in the field, i.e., 59-fold to dinotefuran, 33-fold to clothianidin, 29-fold to acetamiprid, 28-fold to N-methylimidacloprid, 25-fold to thiacloprid, 15-fold to thiamethoxam, 10-fold to nitenpyram, but less than 2-fold to nicotine. In injection bioassays, high resistance to imidacloprid was also found (116-fold). Piperonyl butoxide partially suppressed resistance to imidacloprid, but the resistance level was still over 100-fold, indicating that other mechanisms were primarily responsible for resistance. Low levels of resistance (8- to 10-fold) were found to the nicotinic activator, spinosad, in an imidacloprid-resistant strain collected from the same field in 2004. The cross-resistance seen with all the neonicotinoids tested suggests that the rotation of imidacloprid with other neonicotinoids may not be an effective long-term resistance management strategy. Rotation with spinosad also carries some risk, but it is unlikely that spinosad resistance in this case is mechanistically related to that for the neonicotinoids.