【作者】 孙英健；

【导师】 沈建忠；

【作者基本信息】 中国农业大学 ， 基础兽医学， 2003， 硕士

【摘要】 正文：阿维菌素类药物（Avermectins，AVMs）是由放线菌（streptomyces avermitilis）产生的一组大环内酯类抗生素，通过阻断虫体神经元之间及节肢动物神经末梢和肌细胞间的神经冲动传导，使虫体麻痹而死。AVMs具有优异的驱虫活性和安全性。是目前广泛使用的畜禽体内外抗寄生虫药物，也是农业上广泛使用的高效杀虫剂。本文就阿维菌素B_1a组分(AVM B_1a)对四种土壤中细菌和真菌的数量、呼吸强度的影响及在蚯蚓（Eisenia fetida）体内的蓄积与消除进行了研究。 AVM B_1a对四种土壤环境中微生物的生长情况及呼吸强度的研究结果表明：只有当土壤中的AVM B_1a浓度在83.3mg·kg^-1以上时才对土壤细菌的生长表现出明显的抑制作用，但对土壤中真菌不表现抑杀作用。用密闭法对AVM B_1a对四种土壤中细菌的呼吸强度的研究结果显示，AVM B_1a在1250mg·kg^-1以上时对土壤的微生物的呼吸强度有抑制作用，同时发现土壤本身的营养成分对AVM B_1a的毒性有影响。采用滤纸接触实验和人工土壤实验测定了AVM B_1a对蚯蚓的急性毒性。结果表明，蚯蚓滤纸接触试验的接触毒性LD₅₀为4.63μg·cm^-2（48h），人工土壤法试验蚯蚓的LD₅₀分别为24.13mg·kg^-1（7d）和17.06mg·kg^-1（14d）。 本研究首次建立了AVM B_1a在蚯蚓体内残留的高效液相色谱荧光检测方法。用乙腈作为蚯蚓中AVM B_1a的提取剂，在经碱性氧化铝柱和C₁₈柱的分离纯化后，蒸干、衍生化后用HPLC荧光检测器检测。当添加水平为5ng·g^-1，50ng·g^-1和500ng·g^-1时，平均回收率分别为104.8％，86.6％和83.0％。变异系数在2.99％～7.34％之间。在蚯蚓组织中的最低检出限为0.5ng·g^-1，日内变异系数在3.76％～8.05％之间，日间变异系数在2.89％～7.44％之间。 经对AVM B_1a在蚯蚓的体内蓄积研究发现，蚯蚓对土壤中的AVM B_1a的摄取迅速，至试验的第9～18d其体内AVM B_1a浓度即趋于稳定，在第18d时蚯蚓体内的AVM B_1a浓度分别为106.86ng·g^-1(低剂量组：0.6mg·kg^-1干土)和165.17ng·g^-1(高剂量组：3mg·kg^-1干土)，均低于土壤中的AVM B_1a浓度；另外，经19d的消除试验发现，阿维菌素在蚯蚓体内的消除也很迅速，在消除试验的第2d，蚯蚓体内AVM B_1a浓度即分别降到5.59ng·g^-1（低剂量组）和32.92ng·g^-1（高剂量组），至第19d时，蚯蚓体内的AVM B_1a的浓度分别为1.03ng·g^-1（低剂量组）和2.36ng·g^-1（高剂量组）。上述结果表明，AVM B_1a在蚯蚓体内不具有明显的蓄积作用，但少量的残留能在蚯蚓体内存留较长时间。更多还原

【Abstract】 Content: Avermectins (AVMs) belong to a group of compounds called macrocyclic lactones, which are natural products produced by the microorgamanism streptomyces avermitilis. In recent years the AVMs are used as a potent antiparasitic animal health drug in the treatment of parasitic infections for food producing animals. The AVMs are notable pesticides used in agriculture. In this paper, several studies were conducted to evaluate the ecotoxicity of AVM BU on earthworms (Eiseniafetida) and soil microorganisms.The influence of AVM B1a on microbiological population of bacteria and fungi in the soils that came from four different places is studied in this paper. The results show that the inhibition actions of AVM BU for population of bacteria in the soil come into being only under the case that the concentration of AVM B1a is higher than 83.3 mg.g-1. Effect of AVM B1a on the respiration of microbes in the soils for 24 hours has been studied using the method of direct absorption. The results demonstrated that AVM BU had significant inhibition effect on soil respiration in its higher concentrations. The acute toxicity tests of AVM BU on earthworms were performed using the filter paper contact test and artificial soil test. And the half lethal dosage (LD50) of AVM B1a is 4.63 ug.cm-2 (48h) and 24.13 mg.kg-1 (7d) and 17.06 mg.kg-1 (14d), respectively, for the filter paper test and artificial soil test. All above results suggested that the ecotoxicity of AVM B1a in the soil should be affected by the composition of the soil.A method of determination of AVM BU in earthworms was established by high-performance liquid chromatography (HPLC) with fluorescence detector. Homogenized earthworms sample was extracted by acetonitriie, and cleaned up on alumina B and C18 solid-phase cartridges, followed by derivatization with 1-methylimidazole (1-MIZ) and trifluoroacetic anhydride (TFAA), and analyzed by HPLC with fluorescence detector set at 365 nm excitation and 475 nm emission wavelengths. The average recovery of AVM B,.in earthworms was 104.8%, 86.6% and 83.0%, at the levels of 5 ng.g-1, 50 ng.g-1, 500 ng.g-1. The relative standard deviation (RSD) ranged from 2.99% to 7.34%. The limit of the detection is 0.5 ng.g-1.The rapid uptake of AVM BU was observed and steady-state levels were reached within 9-18 days. On the 18th day, the final concentrations of AVM BU in the earthworms were 106.86 ng.g-1 and 165.17 ng.g-1, respectively, in the low dose group and high dose group. Both of the AVM B1a concentrations in the earthworms are lower than that in the artificial soil. After 19-day elimination test, the concentrations of the AVM Bt. in the earthworms were 1.03 ng.g-1 and 2.36 ng.g-1, respectively, in the low dose group and high dose group. The test of bio-enrichment and elimination of AVM B1a in the earthworms showed that there are no significant enrichment ofAVM B1a, in earthworms, but the trace amount of AVM B1a can be found for a relative long time in earthworms.更多还原