Studies On The Bioactivities Of Polygonum Hydropiper L. Extracts On Insect Pests

In this study, the extractions were separated from Polygonum hydropiper L. and theextractions were bio-assayed against Ectropis obliqua Prout larva and Pieris rapae L., theresults showed that:1,The bio-assayed of crude extractions from Polygonum hydropiper L. against the 3thinstar larvae of Ectropis obliqua Prout showed that, the crude extracts from Polygonumhydropiper L. had great antifeedant activity and growth inhibitory, but contact toxicities wasnot significant. The 95% ethanol crude extract had the best bio-assayed among crude extracts,after 7d, the contact toxic effect was 52.40%, while the antifeedant rate reached 90.29%,84.15% and 76.72% after 12h,24h and 48h; the growth inhibition rate was 81.26% and86.72% after 3d and 7d.2,The experiments of 95% ethanol extractions showed that extracts had significantantifeedant activity and growth inhibitory, normal contact toxicities. The ethyl ether extract hadstronger activities than others, which the antifeedant activities were 99.34%,90.02% and81.25% after 12h,24h and 48h. The activities of growth inhibition were 93.54% and 97.21%after 3d and 7d, the contact toxic effect with corrected mortality rates in 7d was 68.49%; thechloroform extract and ethyl acetate extract had the lower activities than ethyl ether extract.3,From the experiments of the toxic effect of 95% ethanol crude extraction, the AFC₅₀were 1419.06mg·L^-1 and 2951.21mg·L^-1 in 12h and 24h, the regression function in 12h wasy=1.773x-1.153(R²=0.975); LC₅₀ were 34833.73 mg·L^-1, 26242.19 mg·L^-1 and 12473.84 mg·L^-1in 1d,2d and 7d with the regression functions y=1.593x-2.235(R²=0.962),y=1.523x-1.730(R²=0.972), y=1.387x-0.681(R²=0.961).4,The activities of extractions from Polygonum hydropiper L. were significant inantifeedant activity and normal contact toxicities against Pieris rapae L..95% ethanol crudeextract had better activity than others, After 24h,24h and 48h, the contact toxic effect was14.71%,30.30% and 44.83%, the antifeedant activity were 75.27% and 67.04% after 24h and48h; The ethyl ether extraction of 95% ethanol crude extract had stronger activity than others,which corrected mortality rates in 72h was 56.60% and the antifeedant activities was 90.57% in48h, water extraction had the lowest activity with 22.64% corrected mortality rates in 72h.Key words: Polygonum hydropiper L.; Ectropis obliqua Prout; Pieris rapae L.; bio-activity...