Insecticidal Action And Insecticidal Mechanism On Extracts From Polygonum Orientale L.

Polygonum orientale L. is an annual herbs belonging to Polygonum, Polygonaceae. Insecticidal activities on P. orientale L. were seldom reported at home and abroad. The thesis conducted insecticidal activities, insecticidal spectrum, action ways and mechanism of extracts or fractions from P. orientale L.against larvae of Mythimna separate (Walker). Separation and identification of insecticidal active composition, storage stability on fractions in low temperature and artificial planting technology were also researched. The main results show as following:1. Seeds and stems in autumn of Polygonum orientale L. extracted by 5 species different polar solvents, the highest production rate was methanol extract, the lowest production rate was petroleum ether extract, rank orders of production rates were methanol > ethanol > acetone> ethyl acetate > petroleum ether.2. The highest insecticide active parts of P.orientale L. were seeds and stems in autumn.The best extracting solvents of seeds and stems in autumn were ethanol and methanol (industrial grade), respectively. Contact mortalities of ethanol and methanol extracts (diluted 5 times) against 5th instar larvae of M. separate(Walker) were 41.97% and 20.29%, respectively.3. Insecticide active composition in seeds of P.orientale L.were present in the ethyl acetate fraction from seeds, contact mortality of the fraction (diluted 5 times)against 5th instar larva of M. separate Walker was 88.89%. Insecticide active composition of stems in autumn mainly existed in the ethyl acetate fraction from stems in autumn, the next was trichloromethane fraction, contact mortalities were 59.2% and 29%, respectively. Toxicity regression equations of the ethyl acetate fractions from seeds and stems in autumn were 1.6629+2.8035X±0.105 and 1.6269+3.0380X±0.075, respectively; the values of LC50 were 8.6466 and 29.0484g/L.The ethyl acetate fraction from seeds had strong contact effects against 5th instar larva of M. separate Walker, 4th instar larvae of Pieris rapae L., 5th instar larva of Helicoverpa armigera (Hubner), 5th instar larva of Mamestra brassicae(L.), 4th instar larvae of Spodoptera exigua Hubner and 5th instar larva of Agrotis ypsilon (Rottemberg),and contact mortalities were 88.89%,100%,87.5%,90%,93.33% and 100%, respectively when the fraction was diluted 5 times. The fraction had had strong contact effect against 3rd instar larva of Plutella xylostella(L.),too,and contact mortality (diluted 5 times)was 92.85%. The ethyl acetate fraction from stems in autumn had strong contact effect against 4th instar larvae of P. rapae L., contact mortality (diluted 5 times) was 100%.Petroleum ether extract of stems in blossom had more stronger contact effect against Aphis gossypii Glover, contact mortality was 59.2% when the extract was diluted 30 times. The two fractions had no contact effects against A. gossypii Glover, Myzus persicae (Sulzer), Macrosiphum avenae Fabricius, Brevicoryne brassicae (L.)and A. craccivora Koch.Petroleum ether and methanol extracts of flowers in blossom had strong contact effects against Tetranychus cinnabarinus (Boiduval), contact mortalities all were 100% when the two extracts were diluted 100 times.4. The ethyl acetate fraction from seeds of P. orientale L.had strong contact effect against 5th instar larva of M. separate Walker, contact mortality of the fraction (diluted 5 times)was 88.89%. The ethyl acetate fraction from stems in autumn had more stronger contact effect against the larva , contact mortality was 59.2%. The fraction of ethyl acetate from seeds had more stronger stomach poisoning effect against 3rd instar larva of M. separate Walker, adjusted mortality was 57.14%, and inhibition rate of the ethyl acetate fraction from stems in autumn against the third instar larvae was 30.45%. The fraction from seeds had strong anaesthesia action to the larvae, anaesthesia rate was 82% in one hour,regression equation was Y=2.0794+4.0267X, values of RT50 were 5.31 hours. The two fractions had no antifeeding action, systemic action and fumigation action gainst the larvae, and had no contact effects to pupae and ovum of M. separate Walker. The two fractions had no antifeeding action and fumigation action gainst the larvae of P. rapae L., and had no systemic action gainst M. persicae (Sulzer).5. The fraction of ethyl acetate from seeds of P. orientale L. had some extent inhibition effect on Na+-k+-ATPase in 5th larvae of M. separate Walker.6. It can be deduced that insecticide active composition in seeds of P.orientale L. were 14 chemical compound belonging to methadone, alcohol, open loop terpene and five rings terpene silane classes.7. Ethyl acetate fractions from seeds and stems in autumn of P. orientale L. were stable in low temperature.