Preliminary Study Of Insecticidal Activity Of Eugenia Caryophyllata Thunb

Eugenia caryophyllata Thunb. belongs to Myrtaceae. Eugenia (L.). It contains many kinds of active constituents which have obvious pharmacological actions such as sterilization, anti-hypertension, cooling, numbness and acesodyne. In this paper, it was tested with Callosobruchus chinensis Linnaeus and Sitophilus zeamais Motschulsky. The organic solvents of extracting insecticidal active material from Eugenia caryophyllata Thunb. and the action mode of the extracting material to the pests were studied systematically, also separate active material from the plant. The results were as follows:The ultrasonic extraction method was used to extract the active constituents in Eugenia caryophyllata Thunb. by using some organic solvents, such as ethanol, chloroform, ethyl acetate, acetone, petroleum ether and methanol. The insecticidal activities determination to Callosobruchus chinensis Linnaeus showed that the ethanol was the best extraction solvent. The ratio of damage was 4.33% and the deterrent rate of lay eggs was 90.46% at concentration of 2500mg.L-1. The activities of extraction solvent were: ethanol>ethyl acetate>acetone>methanol>petroleum ether>chloroform.The bioassays of ethanol extract by ultrasonic extraction method against Callosobruchus chinensis Linnaeus and Sitophilus zeamais Motschulsk in laboratory were carried out. The bioassay showed that the toxicity of the extract was high. It was have obvious bioactivity on contacting activities, fumigation activities and the repellencies. The LD50 of contacting activities were 88.47μg.cm-2 and 672.67μg.cm-2 at 72h, the LD50 of fumigation activities were 12.41ppm and 25.31ppm at 72h, the LD50 of the repellencies were theⅤlevel. The higher concentration, the more obviously the effect on the pest was. There were obvious difference on experimental population between Callosobruchus chinensis Linnaeus with Sitophilus zeamais Motschulsk. At concentration of 5000mg.L-1, the reproduction inhibition rate of Callosobruchus chinensis Linnaeus was 96.55% and it was 21.71% of Sitophilus zeamais Motschulsk. The extract had effect on eclosion, the higher concentration, the lower rate of eclosion.The active material was obtained from the ethanol extracts by Zhang's methods through systematic extraction, the extraction of ethylether and TLC. Then the bioactivity was tested. The results showed that the fumigation activities of The active material had effect on Callosobruchus chinensis Linnaeus and Sitophilus zeamais Motschulsk. The LD50 of the fumigation activities were 61.43ppm and 303.49ppm at 72h.It was higher than the ethanol extracts. The LD50 of Callosobruchus chinensis Linnaeus is 5 times than that of ethanol extracts, and The LD50 of Sitophilus zeamais Motschulsky is 12 times than that.