Impact of Extracts from Xanthium sibiricum on Aphis glycines and Its Natural Enemy: Harmonia axyridis

The aim of this study was to determine the optimal plant parts and the insecticidal activities of Xanthium sibiricum.Root,stem,leaf and seed of Xanthium sibiricum were selected as materials to extract insecticide by methanol as organic solvent. The insecticidal bioactivities of extracts against Aphis glycines and its effect on Harmonia axyridis were determined. The results showed that extracts from different parts of Xanthium sibiricum could effectively control Aphis glycines. The toxicity tendency exhibited the sequence of leaf stem seed root. The corrected mortality of extract from leaf was 87. 07% after72 h against Aphis glycines and was safe for Harmonia axyridis below the concentration of 75 mg·m L- 1. After extracts from leaf and stem treated potted soybean,the corrected mortality was over 80% at 5 days. Because extracts from leaf and stem was not only toxicant against Aphis glycines but also safe for Harmonia axyridis,it could be acted as the emphases for further study.