鱼类指环虫植物源杀虫剂的筛选

Screening of Botanical Insecticides for Dactylogyrus of Fish

为了探讨植物源杀虫剂(植物提取物)对鱼类指环虫的杀虫活性,以鱼鳃中型指环虫为供试虫,选择具有杀虫抑菌作用的52种药用植物的丙酮提取物进行了离体、活体杀虫活性测定,同时对杀虫效果较好的植物进行不同溶剂提取物杀虫试验,并对杀虫效果好的提取物进行理化检测。结果表明:在提取物供试药材(生药)质量浓度为10 mg/mL条件下离体初筛,得到18种具有较强杀虫效果的植物品种,其中经川楝、博落回、油茶饼、大黄、黄连、牵牛子、苦楝、藜芦、烟草等植物的提取物处理后指环虫能在10 h内死亡,且最低杀虫浓度均低于10 mg/mL(植物质量浓度)。其中博落回、川楝活体杀虫率达85%以上,其余植物提取物达75%以上。川楝乙醇提取物处理杀虫效果最好,浓度在700 mg/L(提取物质量浓度)时,指环虫已全部死亡,此时鱼死亡率仅为4%。同时分析得出乙醇提取物的主要成分是黄酮类、生物碱和萜类,这些物质对指环虫的灭杀起到了关键性作用。

In order to promote the healthy and sustainable development of fish farming industry, the insecticidal activity of botanical insecticides (plant extracts) to fish Dactylogyrus was studied. Medium-sized Dactylogyrus on fish gills was used as the test insect. In vitro and in vivo insecticidal activities of acetone extracts from 52 species of medicinal plants were investigated. Further insecticidal experiments and physiochemical assay of different solvent extracts from the plants with better insecticidal efficacy were carried out. Then 18 species of plants with strong insecticidal efficacy were obtained from in vitro screening at 10 mg/mL mass concentration of the extract (crude drug). After being treated with the extracts of the above 18 plant species e.g. Melia toosendan Sieb. et Zucc., Macleaya, Camellia oleifera, rhubarb, goldthread, kaladana, Melia azedarach, Veratrum L., and tobacco, Dactylogyrus samples died within 10 hours, the lethal dosages were all less than 10mg/ml (mass concentration). Typically the in vivo insecticidal rates of Melia toosendan and Macleaya were over 85%, those of the others more than 75%. Melia toosendan ethanol extract was of the optimum insecticidal effect. When its concentration was 0.7mg/mL (extract mass concentration), all the Dactylogyrus died, whereas the mortality rate of fish was only 4%. Major components of all the ethanol extracts were found to be flavonoids, alkaloids and terpenes, which played a key role in the killing of the Dactylogyrus. As a botanical insecticide, Melia toosendan plant extract provides a direction and practical significance for the efficient, green and environmentfriendly killing of fish Dactylogyrus.