Rhizoma Atractylodis And Ricinus Communis Extracts For Botanical Pesticides

In recent years, great interest has been focused on botanical pesticides due to their attractive advantages including excellent insecticidal performance, environmental-friendly feature, and abundant resources. Rhizoma atractylodis is a traditional Chinese medicine with high medical value, and it not only can be used for antibacteria and antiphlogosis, but also has toxic effects on acarid. Ricinus communis contains a variety of toxins with strong insecticidal activity. The systematic research on the extraction, compostion analysis, and insecticidal activities of the two plants will provide the basis to develop new botanical pesticides.In this paper, the essential oil of Rhizoma atractylodis was extracted using a steam distillation method, and the GC-MS technique was used to determine its chemical composition,28compounds accounting for90%of total oil were identified. The stability of the obtained essential oil was evaluated by GC. The HPLC external standard method was developed to quantificationally determine ricinine in different parts of Ricinus communis and the leaves in different growth periods. It was found that fresh green leaves had the highest content (1.0051%) of ricinine. The extraction and purification methods of ricinine were discussed. It was found that the methylene dichloride extraction approach could completely extract ricinine compared to other methods. The structure of ricinine was characterized by IR, MS and NMR. In addition, the single factor method was used to optimize the extraction of Rhizoma atractylodis and Ricinus communis. The optimal conditions were as follows:10:1ratio of ethanol and materials, extraction time of2h and extraction temperature at80℃for Rhizoma atractylodis, and20:1ratio of ethanol and materials, extraction time of4h and extraction temperature at80℃for castor bean meal. The extracts from the two plants against Spodoptera exigua and Myxus persicae were evaluated by combining the spraying method or/and the leaf-dipping approach. It was found that the essential oil of Rhizoma atractylodis showed stronger insecticidal activity than the ethanol extract, with LC50values of2.78mg/mL and0.62mg/mL against Spodoptera exigua and Myxus persicae after72h, respectively. The LC50values of the ethanol extract from castor bean meal against Spodoptera exigua and Myxus persicae were4.31mg/mL and0.47mg/mL, respectively. Besides, the appropriate compatibility of the essential oil from Rhizoma atractylodis and the ethanol extract from castor bean meal could improve the insecticidal activity.