Studies On Bio-Activities Of Plant Extracts Against Tetranychus Cinnabarinus And Their Active Substances' Extraction

The biological activities of 11 species of plant extracts against Tetran-ychus cinnabarinus were measured in laboratory by leaching stem immersi-on method. The results showed that the biological activities of Galla chinensis, Albizia julibrissin Durazz, platycladus orientalis(L.) France, Rumex japonicas Houtt, Punica granatum Linn, Solanum lycopersicum and Euphorbia australis L. at the concentration of 20 mg/mL were high, with corrected mortality over 90%,24 hours after treatment. According to the results of the above, the contact toxicities of these 4 plant extracts against T. cinnabarinus were tested and the LC50 value of the 7 plant extracts, ranging from low to high, with plant G. chinensis at [(0.6454±0.0569) mg/mL], follo-wed by plant A. julibrissin at [(2.3678±0.0294) mg/mL], plant S. Lycopersi-cum at [(3.7117±0.1203) mg/mL], plant P. orientalis at [(5.3221±0.0325) mg/mL], E. australis at [(6.2726±0.0264) mg/mL], plant R. japonicas Houtt at [(7.9278±0.0256) mg/mL], and plant P. granatum Linn at [(9.2979±0.0194) mg/mL]. The results of the pot experiment showed that the live mites decline rate of G. chinensis, A. julibrissin, P. orientalis and E. australis at the concentration of 20 mg/mL were over 90% at 1 d after treatment, and with the passage of time, the live mites decline rate and corrected control effect had decreased significantly trend. But 6 d after treatment, the live mites decline rate and corrected control effect of G. chinensis, A. julibrissin, P. orientalis and E. australis at the concentration of 20 mg/mL were over 90%The extracts of G. chinensis, A. julibrissin was extracted simultaneousl-y,or sequentially,from the five solvents. The results show that, in sequential extracts, petroleum ether sequential extract of G. chinensis had strongest aca-ricidal activity with corrected mortality 100%, and its LC50 (concentration at which 50% of the mites died) value was 0.4676 mg/mL, followed by acetone sequential extract of A. julibrissin with corrected mortality 98.55% and its LC50 value 9.8201 mg/mL. petroleum ether, ethyl acetate sequential extracts of G. chinensis and 70% ethanol sequential extracts of A. julibrissin had higher biological activities in simultaneous extracts with corrected mortality 100%,100%,98.76% and their LC50 values were 0.4458 mg/mL 1.4629 mg/mL,2.3678 mg/mL. According to the stability test of the active ingredients,the results showed that G. chinensis extracts were not sensitive to temperature, illumina-tion variance and uv irradiation, and also acid and alkaline resistance. A. julibrissin extract after heated had higher activity at first, and then had lower activity, at last had the increased trend, and was sensitive to the light and uv light, had acid resistance but not alkali resistance.In addition, ovicidal activity, oviposit effect and repellency of petroleum ether sequential extract of G. chinensis and n-butanol re-extracts of A. julibri-ssin were studied. The results showed that killing eggs poisonous forces were [(35.2812±0.12) mg/mL], [(11.2131±0.02) mg/mL] respectively at the concentration of 20 mg/ml for 24 h, their oviposition inhibition were 86.33%,52.31%, and their repellency rate were 40.72%,46.29%.The petroleum ether extract was separated into 8 groups with the column chromatography on silica gel. The acaricidal activities of the 8 groups were identified respectively. The bioassay results indicated that the adjusted mortalities of group (G4) had the strongest acaricidal activity with corrected mortality 99.31%,24 hours after treatment. Through separation and purifica-tion of component 4, the results showed that the activity of G4-1 had higher activity with corrected mortality 100%,24 hours after treatment. The G4-1 was analysed by GC-MS. Fifty-two compounds were identified. And the biological activity of palmitic acid ethyl ester, P-Sitosterol and benzoic acid two different butyl acetate were tested. The result showed that three pure substances have certain biological activity, but palm acid ethyl ester had the highest biological activities with corrected mortality 100%,24 hours after treatment at the concentration of 2 mg/mLThe study of the active ingredients of A. julibrissin showed that the most active compounds were found in the n-butanol phase, and its adjusted mortality was 98.56% at a concentration of 10 mg/mL, the LC50 value was 8.2671 mg/mL. The n-butanol re-extracts were separated into 5 fractions with the column chromatography on silica gel. The acaricidal activities of the 5 fractions were identified respectively. The bioassay results indicated that the adjusted mortalities of group 1 (G1) were 100% at a concentration of 10 mg/mL,24 hours after treatment.