关键词: 蓖麻, 淡色库蚊, 粗提物, 毒杀效果

Abstract: Objective To test the toxic effects of the ethanol extracts from Ricinus communis against larvae of Culex pipiens pallens and provide information for the development of new chemicals for mosquitoes control. Methods The dry powder of R.communis was extracted with 95% ethanol solution for 48 h. Then the extracts were diluted with distilled water and bioassay was carried out with the 3^rd instar larvae of Cx.pipiens pallens. Results At the experiment concentration, the extracts of all plant tissues had toxic effects on the 3^rd instar larvae of Cx.pipiens pallens, but the extracts from the tegument of the stem and the root had the strongest toxic effects. When the extracts from the tegument of the stem were used, the mortality reached 100% for 12 h after treatment at the concentration of 2500 mg/L and 94.44% for 36 h at the concentration of 625 mg/L. While the extracts from the tegument of the root were used, the mortality reached 97.78% for 36 h after treatment at the concentration of 2500 mg/L, and 66.67% for 72 h after treatment at the concentration of 625 mg/L. Compared with the control, the average growth duration of the survived larvae to pupation were delayed by 0.5-2.5 days. Conclusion The extracts from the tegument of stem and root showed better toxic effects against the 3^rd instar larvae of Cx.pipiens pallens and the toxic effects of R.communis on mosquito larvae deserve to further study in the future.