【作者】 张鹏；

【导师】 慕卫；

【作者基本信息】 山东农业大学 ， 农药学， 2015， 硕士

【摘要】 韭菜迟眼蕈蚊是为害韭菜的重要害虫之一,严重影响韭菜产量与质量。目前对该虫防治主要利用有机磷等化学药剂,近年来部分地区反映其用药量上升,防治效果下降,亟待筛选高效、低毒的替代药剂及精准施药技术。为明确噻虫嗪防治韭菜迟眼蕈蚊的应用潜力,指导其科学使用,室内测定了噻虫嗪对韭菜迟眼蕈蚊的致毒效应和在土壤中的迁移和淋溶特性,田间研究了噻虫嗪及其代谢产物噻虫胺定向喷淋施药后在土壤中的分布特点、移动性和消解动态、对韭蛆的防治效果、对葱须鳞蛾和蓟马的兼治效果以及其对韭菜生长的影响。主要内容及结果如下:1.采用胃毒触杀联合毒力法比较了噻虫嗪等13种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其对蚯蚓的急性毒性,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其他8种药剂,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。2.采用胃毒触杀联合毒力法、药液定量滴加法、药膜法测定了噻虫嗪和及其代谢产物噻虫胺对不同虫态韭菜迟眼蕈蚊的毒力。结果表明,噻虫嗪和噻虫胺对韭菜迟眼蕈蚊4龄幼虫的LC50分别为14.96 mg/L、3.70 mg/L;对其卵的毒力均较低,LC50分别为113.45mg/L、61.41mg/L;对其成虫的击倒毒力均较高,LD50分别为1.93μg/cm2、1.43μg/cm2。3.采用胃毒触杀联合毒力法测得的LC5剂量(1.158 mg/L)和LC20剂量(3.615 mg/L)噻虫嗪处理4龄韭蛆幼虫,依据两性特定年龄生命表理论评价了其对韭蛆种群特征的影响。结果表明,LC5和LC20处理组与对照组相比,韭蛆的内禀增长率、净生殖率、存活率、生殖值都出现了下降,同时平均世代时间、产卵前期、幼虫期以及蛹期均延长。种群的内禀增长率从对照组的0.1775 d-1降低到0.1502和0.1136 d-1,净生殖率从对照组的61.75粒/头减少到43.36和20.75粒/头。因此,亚致死剂量噻虫嗪对韭蛆种群的增长具有控制作用。4.利用HPLC建立了噻虫嗪和噻虫胺在水和土壤中的检测方法,利用UPLC-MS/MS建立了韭菜中噻虫嗪和噻虫胺的检测方法。结果表明,噻虫嗪在土壤中的平均回收率为89.67%~95.33%,相对标准偏差为1.67%~2.64%,在水中的平均回收率为93.83%~97.17%,变异系数为0.79%~1.66%,在韭菜中的平均回收率为92.36%~106.42%,相对标准偏差7.88%~8.86%;噻虫胺在土壤中的平均回收率为87.83%~97.17%,相对标准偏差为0.79%~1.66%,在韭菜中的平均回收率为95.40%~101.16%,相对标准偏差为8.08%~9.46%。试验结果均符合农药残留分析要求。噻虫嗪和噻虫胺在土壤和韭菜中的最小检出质量分数均为0.01 mg/kg。5.采用振荡平衡法、土壤薄层层析法和土柱淋溶法研究了噻虫嗪在砂土、粉砂壤土和砂姜黑土3种不同理化性质土壤中的吸附和淋溶特性,探讨了农药的吸附与淋溶特性与土壤理化性质的关系以及剂型对农药淋溶特性的影响,并对噻虫嗪和辛硫磷的田间浓度分布作了对比。结果表明,噻虫嗪在3种土壤中的吸附较好地符合Freundlich方程,Kd值分别为砂土1.25、粉砂壤土2.95、砂姜黑土5.10,其大小顺序与Koc值一致。黏粒含量是影响噻虫嗪在土壤中吸附性的最主要因素,有机质含量为次要因素。土壤薄层层析试验和土柱淋溶试验均表明噻虫嗪在3种土壤中的淋溶速率顺序为砂土>粉砂壤土>砂姜黑土,且油悬浮剂、水悬浮剂淋溶量较高,水分散粒剂次之,颗粒剂最低。噻虫嗪比辛硫磷移动性更强,更易达到地下所防治靶标的位置。噻虫嗪存在对地下水污染的潜在风险,特别是在黏粒和有机质含量低的环境下使用时,其风险应该引起足够的重视。6.研究了噻虫嗪和噻虫胺在土壤中的残留动态情况。结果表明,噻虫嗪和噻虫胺在土壤中的消解动态均符合一级反应动力学方程,噻虫嗪在6.0和12.0 kg a.i./ha施药量下,土壤中的残留消解动态方程分别为C=6.1015e-0.0258t(r2=0.9768)和C=12.01131e-0.0237t(r2=0.9579),半衰期为别为26.87和29.25天;噻虫胺在3.0和6.0 kg a.i./ha施药量下,土壤中的残留消解动态方程分别为C=2.5615e-0.0194t(r2=0.9804)和C=7.9136e-0.0192t(r2=0.9884),半衰期为别为35.73和36.10天。7.研究了噻虫嗪和噻虫胺在定向喷淋和灌溉施药方式下在土壤中的分布状况、定向喷淋施药后在田间的移动性、对韭蛆的防治效果和对韭菜生长指标的影响。结果表明,定向喷淋施药比灌溉施药利于药液到达地下靶标位置,且随着土壤深度的增加其浓度越小;经定向喷淋施药后药剂在韭菜根部土壤中的浓度明显高于其在行间土壤中的浓度;施药后120天与7天时相比,药剂在垂直方向上出现下移,在水平方向上随水流方向移动;除噻虫嗪6.0 kg a.i./ha外,噻虫嗪和噻虫胺定向喷淋处理对韭菜迟眼蕈蚊的防效均可维持韭菜整个养根期,且对韭菜生长有促进作用。在收获的三刀韭菜样品中,仅第一刀的12.0 kg a.i./ha噻虫嗪和6.0 kg a.i./ha噻虫胺处理检测到两药剂,且样品中其浓度分别为0.09 mg/kg和0.05 mg/kg。因此,利用噻虫嗪和噻虫胺在养根期韭菜行内定向喷淋施药防治韭菜迟眼蕈蚊是可行的。更多还原

【Abstract】 The chive gnat Bradysia odoriphaga Yang and Zhang(Diptera: Sciaridae) is the major insect pest damaging Chinese chive in China, and seriously affects production and quality of Chinese chive. Currently, the prevention of this pest mainly depended on organophosphorus insecticides. However, in recently, the application rates of pesticide were increasing and the control efficacy was declining in some area. Screening low toxic and high effective alternatives and their matched precise application technique against B. odoriphaga are need. To determine the potency of the second generation of new neonicotinoid insecticides to control B. odoriphaga and their scientific use, the toxic effects of thiamethoxam to B. odoriphaga and adsorption and leaching of in soil was studied. And their distribution in soil after the directional spray-washing, moving characteristic, distribution and degradation in the field, control effect against B. odoriphaga and impact to the growth index of Chinese chive were also investigated. The results were summarized as follow:1. The toxicities of thiamethoxam, and other 12 kinds of insecticides to B. odoriphaga by stomach-contact combination toxicity method were tested, meanwhile, acute toxicity of pesticides above to earthworms was determined using artificial soil method. Selective toxicity of pesticides above to B. odoriphaga and earthworms were confirmed by pot experiments. The results showed that the toxicity of imidacloprid, clothianidin, dinotefuran, thiacloprid and thiamethoxam to the 4th instar larvae of B. odoriphaga were significantly higher than other 8 pesticides and the LC50 of these five pesticides to tebufenozide were 101.6-, 55.0-, 32.9-, 27.2-, 13.6- folds respectively. For the 13 pesticides, the toxicity of imidacloprid, acetamiprid, clothianidin and dinotefuran to earthworms were medium while the other pesticides were low. In the pot experiments, the insecticidal effect and seedling protecting effect of imidacloprid, thiamethoxam, chlorpyrifos, fosthiazate and lambda-cyhalothrin were better than that of pesticides, and only thiamethoxam had inconspicuous lethality.2. The toxicities of thiamethoxam and its metabolic product clothianidin to different stages of B. odoriphaga were tested by stomach–contact combination toxicity method, the dripping quantitative liquid method; pesticide-membrane method. The results showed that the LC50 of thiamethoxam and clothianidin to B. odoriphaga larvae were 11.92 mg/L and 3.70 mg/L, their toxicities to eggs were low(thiamethoxam: LC50=113.45 mg/L; clothianidin: LC50=61.41mg/L), and their knockdown of thiamethoxam and clothianidin against B. odoriphaga adults were high(LC50 thiamethoxam: LD50=1.93 μg/cm2; clothianidin:LD50=1.44 μg/cm2).3. The standard contact and stomach bioassay method was used to assess the effects of sublethal(LC5=1.158 mg/L, LC20=3.615 mg/L) concentrations of thiamethoxam on the demographic parameters of B. odoriphaga, and data were interpreted based on the age-stage, two-sex life table theory. After thiamethoxam treatment, the intrinsic and finite rates of increase, net reproduction rate, survival rate, and reproductive value were all marked ly decreased, while the mean generation time, total preovipositional period, and larval and pupal duration were prolonged, compared with controls. The intrinsic rates of increase dropped from 0.1775/day to 0.1502-0.1136/day. Following LC5 and LC20 treatments, net reproduction rate dropped from 61.75 offspring/individual(control) to 43.36 and 20.75 offspring/individual, respectively. Sublethal concentrations of thiamethoxam decreased the developmental rate of laboratory populations of B. odoriphaga, suggesting that such doses may be useful in integrated pest management strategies.4. Analytical method for simultaneously detecting thiamethoxam and clothianidin residue in water and soil samples was established by HPLC and analytical method for simultaneously detecting thiamethoxam and clothianidin residue in leek samples was also established. The results showed that average recoveries of thiamethoxam in soil samples ranged from 89.67%-95.33%, the relative standard deviation was 1.67%-2.64%, its average recoveries in water samples ranged from 93.83%-97.17%, the relative standard deviation was 0.79%-1.66%, its average recoveries in leek samples ranged from 92.36%~106.42%, the relative standard deviation was 7.88%~8.86%; the average recoveries of clothianidin in soil samples ranged from 88.91%~93.34%, the relative standard deviation was 1.68%~2.15%, its average recoveries in leek samples ranged from 95.40%~101.16%, the relative standard deviation was 8.08%~9.46%. The lowest detectable concentration of thiamethoxam and clothianidin in leek and soil samples were 0.01 mg/kg, respectively.5. To study the influence of soil basic physical and chemical properties on the adsorption and leaching behavior of pesticide in soil, the adsorption and leaching of thiamethoxam onto three different soils including Sandy soil, Silt loam soil, Shajiang black soil, conducted by oscillation equilibrium experiment, soil thin layer chromatography and column leaching. And comparative concentration distributions of phoxim and thiamethoxam in soil after their application were also determined. The results showed that the adsorption of thiamethoxam in the soils could be well fitted by the empirical Freundich isotherm. The adsorption constants(Kd) were 1.25, 2.95 and 5.10 in Sandy soil, Silt loam soil, Shajiang black soil, respectively. Clay content was dominant factor affecting the adsorption of thiamethoxam in soils and the soil organic matter content was the next factor. The leaching of thiamethoxam was in order of Sandy soil>Silt loam soil>Shajiang black soil, and higher amount of leaching was the oil suspended agent and suspension concentrate, followed by water dispersible granule, the granulehad the lowest amount of leaching. Thiamethoxam had stronger mobility than phoxim, and was easier to move to the underground soil where biological targets lived in. These results demonstrated that thiamethoxam has potential risk of contaminating groundwater. Attention should be paid to its application, particularly in the soil of law clay content and organic matter content.6. Residual dynamic of thiamethoxam and clothianidin in soil was studied. Results for residual dynamic test showed that the degradation trends of thiamethoxam and clothianidin in soils were line with a kinetic equation. Equation of residues and degradation dynamics of thiamethoxam applied at 6.0 and12.0 kg a.i./ha were C=6.1015e-0.0258t(r2=0.9768)and C=12.01131e-0.0237t(r2=0.9579), their half-lives were 26.87 and 29.25 days; Equation of residues and degradation dynamics of thiamethoxam applied at 3.0 and 6.0 kg a.i./ha were C=2.5615e-0.0194t(r2=0.9804) and C=7.9136e-0.0192t(r2=0.9884), their half-lives were 26.87 and 29.25 days.7. The distributions of thiamethoxam and clothianidin in soil after the directional spray-washing and chemigation, moving characteristic in the field, control effect against B. odoriphaga and impact to the growth index of Chinese chive were studied. The results showed that application of insecticides using the directional spray-washing was easier to reach the target than those using the chemigation, and the concentration of insecticide in the soil decreased with the increase of soil depth; the concentration in the rhizosphere soil was higher than those in the inter-row soil of Chinese chive. Comparing to the distribution at the 7th day after application, insecticide moved much deeper and wider at the 120 th day after application. The control effect of thiamethoxam 12.0 kg a.i./ha and clothianidin 3.0 kg a.i./ha and 6.0 kg a.i./ha could last the whole root-rearing period and promote the growth of Chinese chive. Therefore, thiamethoxam and clothianidin could be used for the control B. odoriphaga in the root-rearing period of Chinese chive by the directional spray-washing application.更多还原