The Preventive Effects Of Plant Extracts Treatment On Pest Mites

In order to develop green, safe and environmental friendly botanical acaricides, thisexperiment primary studied18species of plants which had some insecticidal substances,such as alkaloids and flavonoids against female adults and eggs of Tetranychus urticae,and finally selected Ailanthus altissima as the research object. Then systematicallystudied Ailanthus altissima extracts biological activity against Tetranychus urticae; asbio-active guided isolation to seek one or more substances from Ailanthus altissima haveacaricides activity. This study mainly obtained the following results:1. Acaricidal plants screeningTo screen new botanical acaricide, Ethanol as exteaction solvent, the biologicalactivities of18species of plant ethanol extracts against female adults and eggs ofTetranychus urtica were measured in laboratory by slide-dip method and leaf dippingmethod. After72hours treatment, the biological activities of Mirabilis jalapa, Ailanthusaltissima, Acer palmatum, Viola philippica, Galinsoga parviflora and Chenopodiumalbum at the concentration of10mg/mL were high, the modified mortality were100%.According to the the above results, the contact toxicities of these6plant extracts againstfemale adults and eggs of Tetranychus urticae were tested and the LC50value of the6plant extracts against adult female mites were ranging from3.679mg/ml to7.378mg/ml,and the LC50value against the eggs were ranging from11.176mg/ml to60.651mg/ml.The LC50s of ethyl alcohol ailanthus altissima extract against female adults and eggs ofTetranychus urticae were4.686mg/mL and11.176mg/mL, respectively.2.Acaricidic activity of ethanol ailanthus altissima extractThis research chosed four kinds of different polarity solvent, including: petroleumether, acetone, chloroform and ethanol, respectively on indoor parallel extraction of Ailanthus altissima, a total of four kinds of extracts were obtained. Ethanol had thehighest extraction rate, followed by acetone, chloroform and petroleum ether, thissuggested that the polarity composition content was higher in ailanthus altissima leaves.The biological activities of four kinds of extracts against female adults and eggs ofTetranychus urtica were measured in laboratory by slide-dip method and leaf dippingmethod, the results showed that the biological activities of ethanol ailanthus altissimaextract were the highest, with modified morality were pespectively88.10%and96.15%,24hours and48hours after treatment; egg hatching rat was51.11%,7days aftertreatment, significantly lower than the other three kinds of solvent extraction, so the bestsolvent was ethanol. Subsequently, acaricidal activity of the extraction of the ethanolailanthus aitissima againet Tetranychus urticae was investigated: every concentration ofthe ethanol ailanthus altissma extract showed fine oviposition deterrence effect againstTetranychus urticae. The higher concentration, the more deterrence restrain. when theconcentration was12.8mg/mL, the oviposition deterrence index were0.9883and0.9933,the oviposition inhitition rate were up to99.40%and99.66%, respectively,24hours and48hours after treatment. Ethanol ailanthus altissma extract also showed fine deterrenteffect against Tetranychus urticae, especially the concentration above6.4mg/mL, thedeterrent effect over86.67%,24hours after treatment, but along with concentrationdecreased, the deterrent rate declined fast, till1.6mg/mL, the deterrent effect disappeared.Toxicity of ethanol ailanthus altissima extrat against female adults of Tetranychus urticaewere measured, the concentration was0.8mg/mL, the modified mortalities was over50%,and the higher the concentration, the stronger the toxicity.3. Bio-active guided isolation of acaricidal active materialThe active ingredient of the ethanol of ailanthus altissima was separated use ofdifferent polarity solvent, column chromatography and thin layer chromatography,determination of the contact acaricidal from different fractions obtained. Water portationextracted from ethanol extract of ailanthus altissima had the highest extractionrate(51.30%), followed by n-butanol(27.60%), ethyl acetate(11.50%) and petroleum ether(9.60%). By trace sampler quantitative drop method, the acaricidal activity of fourskinds of extracts were evaluated. Part of n-butanol extraction possed the strongly activity,the modified mortality was44.94%, followed by water and ethyl acetate extraction, theweakest activity extraction was petroleum ether, the modified mortality only had4.49%,24hours after treatment; after72hours treatment, the modified mortality of n-butanolextraction was up to100%, followed by ethyl acetate extraction, with the modifiedmortality of97.33%, while the modified mortality of petroleum ether extraction was69.33%. The results above concluded that the most active ingredients from ailanthusaltissima focused on in the n-butanol phase. Based on silica gel column chromatographyseparation and examination of thin-layer chromatography, this study carried out theacaricidal activity against Tetranychus urtica of the n-butanol extract from ethanolailanthus altissima extract had isolated from silica gel and thin-layer chromatographywere grouped into22fractions. The acaricidal activities of the22fractions wereidentified respectively. The bioassay results indicated the modified mortalities of group10were48.53%at a concerntration of10mg/mL,48hours after treatment.