【作者】 刘伟；

【导师】 吴文君；

【作者基本信息】 西北农林科技大学 ， 农药学， 2010， 博士

【摘要】 研究农药在防治对象及被保护作物中的穿透与代谢规律,有助于了解该农药的作用方式、解毒代谢等毒理学问题,亦有助于该农药的合理施用。同样,研究农药在水体、土壤中的降解规律及在收获作物中的残留动态,有助于对该农药的安全性评价及制定安全使用标准和残留标准。苦皮藤素V是我国植物杀虫剂苦皮藤素乳油和微乳剂中主要杀虫活性成分之一,迄今没有系统的上述相关内容的研究。为此,本论文研究了苦皮藤素V在昆虫、植物、水体和土壤中的环境行为。主要研究结果如下所述:1.以粘虫(Mythimna separata)6龄幼虫和小地老虎(Agrotis ypsilon)5龄幼虫为试虫,在其前胸背板点滴给药。处理后1～6h,在试虫血淋巴中采用HPLC分析方法均为检测到苦皮藤素V;采用HPLC-MS/MS分析方法可以检测到苦皮藤素V,但含量极低,处理后4h的含量分别为0.169μg·mL-1和0.078μg·mL-1,说明苦皮藤素V很难穿透试虫体壁进入血腔。苦皮藤素V以载毒叶片饲虫法处理试虫,处理1h后粘虫幼虫和小地老虎幼虫血淋巴的苦皮藤素V含量分别为1.74μg·mL-1和1.65μg·mL-1,处理4h后,血淋巴的苦皮藤素V含量达峰值,分别为4.54μg·mL-1和5.81μg·mL-1,说明被摄入消化道的苦皮藤素V能迅速穿透肠壁进入血腔。2.苦皮藤素V经口被摄入试虫体内很快被代谢解毒。在6龄粘虫幼虫和5龄小地老虎幼虫体内的代谢动态符合负指数方程,分别为C=92.33e-0.0528t和C=88.30e-0.1268t,半衰期分别为13.1h和5.5h,说明小地老虎幼虫代谢苦皮藤素V的速率远大于粘虫幼虫。代谢速率的差异,可能是苦皮藤素V对两种试虫的选择作用机理之一。3.增效剂S16和TPP与苦皮藤素V混用后,可明显抑制苦皮藤素V在粘虫和小地老虎幼虫体内的代谢速率。在小地老虎幼虫体内,处理8h、24h后,S16可抑制苦皮藤素V代谢36.11%和14.50%,TPP可抑制苦皮藤素V代谢46.38%和25.56%。在粘虫幼虫体内,处理8h、24h后,S16可抑制苦皮藤素V代谢21.35%和4.94%,TPP可抑制苦皮藤素V代谢21.14%和11.95%。这些结果,说明苦皮藤素V在试虫体内的代谢主要由多功能氧化酶和羧酸酯酶催化。4.研究结果表明,苦皮藤素V既可通过蚕豆苗(双子叶植物)的根系进入植物体内上行输导,根系在10μg·mL-1浓度的水体中48h,蚕豆苗中苦皮藤素V的含量为1.72μg·g-1;又可通过叶片吸收进入植物体内上行输导,以200μg·mL-1浓度喷施中层叶片,48h后上层叶片中苦皮藤素V的含量为0.77μg·g-1,说明和根系的穿透吸收相比,从叶片的穿透吸收比较困难。研究结果还表明,和蚕豆苗相比,水体中苦皮藤素V更容易穿透小麦苗(单子叶植物)根系表面保护层进入植株体内上行输导,处理48h后小麦苗中苦皮藤素V含量达2.72μg·g-1;但苦皮藤素V水溶液浇施于土壤后,由于土壤对苦皮藤素V强烈的吸附作用,因此难以通过根系吸收进入植株体内。5.比较了苦皮藤素I、苦皮藤素V、NW28和NW53四种不同结构类型的二氢沉香呋喃类化合物不同pH水体中54℃条件下的稳定性。结果表明,在pH 4水体中,苦皮藤素I、苦皮藤素V及NW53比较稳定,24h水解率分别为10.43%、8.93%及6.60%,而NW28相对不稳定,24h水解率为19.75%;pH 7水体中,苦皮藤素I、苦皮藤素V及NW28较稳定,24h水解率分别为12.00%、12.03%及6.43%,而NW53稳定性较差,24h的水解率达50.55%;在pH 10水体中,苦皮藤素I、苦皮藤素V、NW28及NW53均不稳定,半衰期分别为1.7h、14.1h、7.1h及0.9h。采用MS及MS/MS技术对苦皮藤素V主要水解产物的结构进行了初步分析。结果表明,水解产物都是1～3个酯键断裂形成的,而且均发生在C-1、C-2、C-8及C-9位,没有发现C-13位酯键水解,也未发现7羟基(全水解)的水解产物。6.室内模拟条件下,苦皮藤素V在不同类型土壤中的降解速率差别较大,其降解速率依次为天津碱土>东北黑土>江西红土>关中黄土,其降解动态方程及半衰期依次为:Ct=9.613e-0.0321T,21.59d;Ct=10.592e-0.0219T,31.65d;Ct=10.261e-0.0123T,56.35d;Ct=11.275e-0.0118T,58.74d。苦皮藤素V在土壤中的主要降解产物和在水体中的降解产物相似,都是1～3个酯键断裂形成的,而且均发生在C-1、C-2、C-8及C-9位。7.大田施药条件下,苦皮藤素V在白菜中的消解动态符合负指数方程Ct=1.210e-0.0588T,半衰期为11.8d;在土壤中的消解动态亦符合负指数方程Ct=0.0596e-0.0475T,半衰期为14.6d。在推荐最高剂量5倍浓度下(苦皮藤素V 15mg·kg-1)施药3次,距最后一次施药14d后,白菜中的苦皮藤素V最终残留量为0.067mg·kg-1,属于低残留农药。更多还原

【Abstract】 To investigate the discipline of the penetration and metabolism of pesticides in the control objects and protected crops will help to understand the mode of action, detoxification and other toxicology problems, and it also contribute to the rational application of pesticides. Similarly, researches on the degradation of pesticides in water and soil, and the residue dynamics in harvested crops, will be helpful to evaluate the safety, to develop the standards of safe use and pesticides residue.As one of the major active ingredients of the botanical pesticide, celangulins formulated as emulsifiable concentrate and micro-emulsion, celangulin V has never been thoroughly investigated in terms of the above mentioned fields. Therefore, the penetration and metablolism of celagulin V in the insects and plants, the environmental behaviour of celangulin V in aquatic system and soil were studied in the program. The main findings are as follows:1. The 6th instar larvae of armyworm(Mythimna separata) and the 5th instar larvae of black cutworm(Agrotis ypsilon) were used as test insects. The acetone solution of celangulin V was delivered in its pronotum by the method of drip administration. In the insect hemolymph, celangulin V was not detected by HPLC-UV analysis after the treatment of 1~16h. While minimal celangulin V was detected by HPLC-MS/MS, the contents were 0.169μg·mL-1 and 0.078μg·mL-1 after the treatment of 4h, which means that penetrating from the integment into the blood cavity was difficult for the tested chemical. Feeding the tested insects with leaves discs contain poison, the contents of celangulin V in the larvae hemolymph of armyworm and black cutworm were 1.74μg·mL-1 and 1.65μg·mL-1 after treatment 1h, and it achieved peak levels after 4h, the contents were 4.54μg·mL-1 and 5.81μg·mL-1, which indicated that celangulin V ingested into digestive tract could rapidly penetrate intestinal lining into the blood cavity.2. Celangulin V ingested by oral could be rapidly metabolized via detoxification. The metabolism of celangulin V in the body of the two tested insects conformed to a negative exponential function, the equations for the 6th larvae of armyworm and the 5th larvae of black cutworm were C = 92.33e-0.0528t and C = 88.30e-0.1268t, half-life were 13.1h and 5.5h, respectively. The metabolism rate of celangulin V in black cutworm larvae was much greater than that of armyworm larvae. Difference in metabolism rate might be one of the selective toxicity mechanisms of celangulin V against two tested insects.3. After administration with a mixture of celangulin V with synergist S16 and TPP, the metabolism rate of celangulin V in armyworm and black cutworm larvae could be inhibited obviously. In the case of black cutworm larvae, the metabolism of celangulin V were inhibited 36.11% and 14.50% by S16, 46.38% and 25.56% by TPP after treatment 8h and 24h, respectively. In the case of armyworm larvae, the metabolism of celangulin V were inhibited 21.35% and 4.94% by S16, 21.14% and 11.95% by TPP after treatment 8h and 24h, respectively. The results indicated that the metabolisms of celangulin V in tested larvae were mainly catalyzed by mixed function oxidase (MFO) and carboxyl esterase.4. The results showed that celangulin V could be adsorbed by root system or leaves, and then upstream in broad bean seedling (dicotyledons). Dipping the roots in the concentration of 10μg?mL-1 aquatic system for 48h, the content of celangulin V in the plant was 1.72μg?g-1. Spraying the middle leaves with 200μg?mL-1 solutions, the content of celangulin V in the upper leaves was 0.77μg?g-1 after 48h. It indicated that the penetration into root was much easier than into leaves. In addition, celangulin V could penetrate wheat (monocot) seedling roots more easily than that of broad bean in aquatic system, the content of celangulin V in the wheat seedling was 2.72μg?g-1 after 48h. However, the intake of celangulin V by root from soil treated with the solution was difficult and it might due to celangulin V was absorbed strongly by soil.5. The stability in different pH aquatic systems of celangulin I, celangulin V, NW28 and NW53, four types of dihydroagarofuran compounds, was investigated under 54℃. The results showed that celangulin I, celangulin V and NW53 were stable at pH 4, their hydrolysis rates were 10.43%, 8.93% and 6.60% after 24h respectively, while NW28 was relatively unstable, its hydrolysis rate was 19.75%. Celangulin I, celangulin V and NW28 were stable at pH 7, their hydrolysis rates were 12.00%, 12.03% and 6.43% after 24h respectively, while NW53 was less stable, and its hydrolysis rate was 50.55%. At pH 10, celangulin I, celangulin V, NW28 and NW53 were unstable and their half-life was 1.7h, 14.1h, 7.1h and 0.9h, respectively.The structures of the major hydrolysis products of celangulin V were analyzed by MS and MS / MS technique preliminary. The results showed that all hydrolysis products were derived from 1~3 ester bonds cleavage, and they all occurred in C-1, C -2, C-8 and C-9 positions, no products were observed derived from the cleavage of ester bond at C-13. At the same time, seven hydroxyls derivative (full hydrolysis product) was also not observed.6. The results of laboratory simulation tests indicated that the degradation rate of celangulin V in different types of soil varied greatly, their order of degradation rate was Tianjin alkaline earth > Northeast black earth> Jiangxi red earth> Guanzhong loess, the dynamic equation and the half-life of degradation were: Ct = 9.613e-0.0321T, 21.59d; Ct = 10.592e-0.0219T, 31.65d; Ct = 10.261e-0.0123T, 56.35d; Ct = 11.275e-0.0118T, 58.74d. The main degradation products of celangulin V in soil were similar with that in water.In field trials, the degradation dynamic of celangulin V in cabbage was fit to the negative exponential equation Ct = 1.210e-0.0588T and half-life was 11.8d. The degradation dynamic in soil was also fit to the negative exponential equation Ct = 0.0596e- 0.0475T and half-life was 14.6d. The results of ultimate residue test showed that the content of celangulin V in cabbage was 0.067 mg·kg-1 , which was sprayed with quintuple of the recommended high dose for three times, and was harvested after 14 days of the last application. It indicated that celangulins formulation was belonging to low-residue pesticide.更多还原