Biological Activity of Different Solvent Extracts from Xanthium sibiricum on Cotton Bollworm
Cotton bollworm(Helicoverpa armigera(Hübner)),as a pest with high adaptability,impacts photosynthesis and fruit of peanuts by feeding on foliage and boring the flower buds resulting in a significant decrease in peanut yield.The pest can reduce the peanut yield by 20%to 50%,and even lead to peanut failure in severe cases.In order to reduce the use of chemical pesticides in peanut fields and protect the ecological environment,in this study,using Xanthium sibiricum as the material,the insecticidal activity of Xanthium sibiricum extracts against cotton bollworm larvae was determined by the spray method and leaf soaking method.The results showed that extracts from different solvents of Xanthium sibiricum had contact killing,antifeedant,gastric toxicity,and growth inhibition effects on the 3rd instar larvae of cotton bollworm.The higher the concentration of the extracts were,the more obvious the effect was.Among them,the effect of chloroform extract against cotton bollworms was better than that of methanol extract and ethyl acetate extract.This indicated that the active components solubilities of Xanthium sibiricum were different in various solvents,thereby its toxicity against cotton bollworm larvae was affected.The contact-killing lethal concentration(LC50)of chloroform extract after 72 h was 0.246 5 g/L.The concentration of selective antifeedant activity(AFC50)was 0.188 0 g/L at 24 h,and the concentration of non-selective AFC50 was 0.188 7 g/L.After 7 days of treatment with chloroform extract,the LC50 of gastric toxicity was 0.389 7 g/L.After 72 h of treatment with chloroform extract,the IC50 was 0.011 2 g/L.This indicated that the extracts not only killed larvae but also significantly inhibited their growth.Therefore,the chloroform extract of Xanthium sibiricum had high insecticidal activity against cotton bollworm larvae,and Xanthium sibiricum had potential for research and development as a plant-based pesticide.
万方数据
维普
