Study on Insecticidal Activity of the Extract of Hibiscus trionum by Different Solvent to Plutella xylostella

Taking Hibiscus trionum L.as an investigating object,ethanol extracts from Hibiscus trionum L.were obtained through alcohol-UW extracting.The activities of extracts to Plutella xylostella were tested to calculate the mortality rate and the corrected mortality rate.The results showed that the ethanol-extracts from H.trionum had the stronger activity.LC50 was 3.2 mg.mL-1.The activities of each extract was in order as follows:chloroform petroleum ether ethyl acetate butanol water.The extracts by chloroform for 72h had the highest contacting toxicity to the 3rd instar larva,with the corrected mor-tality rate of 96.67% resp.The result also indicated the insecticidal active substances in H.trionum were a kind of puny po-lar compounds.