Studies Of Antifeeding Activity And Mechanism Of Polygonum Orientale L. Against M.Persicae (Sulzer)

The research with Polygonum orientale L. of Polygonaceae extensively distributed in national and each province was experimental material, used extracts from root, stem, leaf and seed by dipped in three kinds of solvents: petroleum ether, chloroform, methanol against M.persicae(Sulzer) extensively damages fruit trees, vegetables, tobacco etc. The extracts were used for tests of the bioactivity and mechanism, and material of antifeeding activity was proceedingly separated and purified, the experimental result was as follows: In the test of antifeeding activity, the foliar extracts of petroleum ether and methanol ,the stem extracts of petroleum ether and methanol expressed antifeeding activity obviously, antifeeding rate could attain 70% above, choosed the foliar extract of methanol ( PMEE) did the further analysis, along with the increasement of the density, antifeeding rate too at increase. Experimental result in the field expressed foliar methanol extract of Polygonum orientale L. against M.persicae(Sulzer) had good effect under the higher density(1%), correcting effect was 88.4% after 7 days and the effect in the field holded 5 to 7 days. By extracting to PMEE, the extract rate with petroleum ether was highest in petroleum ether, chloroform, ethyl acetate and methanol and water. Testing the bioactivity of the different extracts proceedingly, ethyl acetate extract had higher antifeeding activity. Separating and purifying the ethyl acetate extract of PMEE by silica gel column and TLC analysis, the fractions with the same compositions were merged . Among 16 fractions at 254 nm the fraction8 was seen a blue fluorescent spot, the rest fractions had no obvious fluorescent spot. Furthermore, the fraction8 had obvious antifeeding activity,24 hours antifeeding rate as to 96.98%, the rest had no the obvious activity. The research of EAG(electroantennography) expressed the fraction 8 had obvious EAG effect.