Study On Insecticidal Constituents Of Polygonum Hydropiper Linn

Insect pest was one of the main factors which had restricted with the highproduction, high quality, highly efficient of tea plants. There are so many kindsof insect pests on tea plants, and nearly 1000 species were recorded in the world.400 species insect pests were common on tea plants, including 50-60 importantspecies, which creates the tea output to lose approximately 15%. Ectropisgrisecens warren was main harmful insect in tea garden in China. It has a fewgenerations, and also long damage time while occurred. Cyhalothrin, bifenthrin,decamethrin were used to prevent and control Ectropis grisecens warren in teagarden at present. After using these pesticides for a long time, Ectropisgrisecens warren had pesticide resistance, and the pesticide residue of tea wasappeared. To solve these problems, it was important to develop and promotenon-polluted pesticides with high activity, low toxicity and low residue, insteadof organic chemical pesticide. It was the key point in development ofnon-polluted tea, and it has the extremely vital significance in such affects asenhancing output and quality of tea, keeping ecological balance, and protectingand using natural enemies.Biopesticide instead of chemical pesticides was the trend of development ofnon-polluted agriculture. China hasn't any biopesticide which ownedindependent intellectual property rights, although such research work had beencarded for a long time. However, the development of organic food and greenfood need biopesticide. To seek insecticidal constituents from natural products,especially from plants was the important method to develop new pesticide.Polygonum hydropiper L. belongs Polygonaceae, Polygonum L., one kind ofannual herb, was traditional Chinese medicine of China. And it can be found inmajority of areas in our country. Antifeedant and antixenosis of Polygonumhydropiper L. against insect pests had vital significance to serve for theagricultural production.Compared with 15 kinds of plant extracts with 4 different kinds of solventsagainst 3rd instar larvae ofEctropis grisecens warren, Polygonum hydropiper L.extract had the best insecticidal effect. Tests of 5 kinds of Polygonum hydropiperL. organic solvents extracts showed that ethyl ether extract had the strongestinsecticidal effect. The chemical constituents of the extract were analyzed byGC-MS, the phenolic was the main chemical substance. The process parameters of the separation and purification of phenolic with different columns andsolvents were studied. Identification of monomers with IR,MS,UV,NMRshowed that the insecticidal substance of Polygonum hydropiper L. was eugenol.Finally using eugenol to do different drug efficacy experiments, the relationshipbetween eugenol and AchE, GST have been studied.The results were as follows:1. Among four different extracts of 15 kinds of plants against 3rd instarlarvae of Ectropis grisecens warren, 95% ethyl alcohol extact of Polygonumhydropiper L. was the most effective one, and it had strong antifeedant andcontact action. 48 hours after treatment, the average antifeedant rate was 83.41%,death rate was 46.67% 3 days later.2. Two methods of extraction and three solvents were selected to obtainextracts from Polygonum hydropiper L., moreover, active composition wasseparated form crude extracts primarily. The biological activities of the foursamples were tested against Pieris rapae L.. The results showed that theseextracts had higher antifeeding effect and contact toxity against Pieris rapae L..In these extracts, the extract with 95% ethanol as solvent had the strongestbiological activities, antifeeding rate in 24h reached 75.27%, corrected mortalityin 72h reached 44.83%. The different solvent extraction of the whole ofPolygonum hydropiper L. with ethanol by dip(PHEE)had higher antifeedingeffect and contact toxity against Pieris rapae L.. In these extracts, the etherextract of PHEE had the strongest biological activities, antifeeding rate in 48hreached 82.93%, corrected mortality in 72h reached 56.60%.3. Use different solvents to extract EE, each extract had antifeedant andcontact action, among them, EE ethyl alcohol extact had the best effection. Hasbeen treated after 12h, 24h, 48h, the antifeedant rates of 3rd instar larvae ofEctropis grisecens warren were 99.34%, 90.02%, 81.25%, separately. Thecontact action rate was 68.49%.4. EE ethyl alcohol extract was analyzed by GC-MS, and 6 kinds ofcompound were discovered: 2-methoxy-4-vinylphenol, 4-allyl-2-methoxyphenol,2,4-di-tert-butylphenyl, di-iso-nonylphtalate, diheptyl phthalate and dibutylphthalate. The first two substances had strong insecticidal effect.5. Isolate insecticidal constituents, active part of Polygonum hydropiper L.was essential oil, and one monomer has been separated. It was4-allyl-2-methoxyphenol, also short for eugenol. 6. Tests of eugenol against 3rd instar larvae ofEctropis grisecens warren,which indicated that Ectropis grisecens warren, had strong antifeedant to theleaves treated by eugenol. Eugenol had obvious stomach toxicity and contactaction. Moreover, the eugenol showed inhibitive function on weight of instarlarvaes.7. Research on mechanism of insecticidal constituents from Polygonumhydropiper L. showed that eugenol can suppress AchE activity, suppression ratereached 73.57% after 2 days, and it decreased by days till 5 days later,suppression rate dropped to 40.43%. Eugenol also suppressed GST activity.After 2d, suppression rate was 64.26%, and 51.0% after 3 days, it decreased to20.38%, 9.38% at 4th and 5th day seperately.