| A noxious plant, W. chamedaphne was investigated for its acarocidal activity against T. Viennensis , a serious pest of many crops including apple trees in china. WCME, crude extract extracted by respective immersion, was separated by liquid-liquid distribution and purified through column chromatograghy, and its active constitutes, WCME-7 and WCME-11, were separated. Their activities to egg, nymph and adult, active methods and active mechanism were studied. The results indicated: 1.To the female adult, WCME appeared a strong acarocidal activity, LC50 value was 2.1855 mg extract/ ml, the activity of extraction of petroleum ether from WCME were 2.83 times against the activity of WCME. By column chromatograghy, the activities of WCME-7 and WCME-11 got 5.59 and 8.54 times respectively. Particularly the LC50 value of WCME-11 reached 0.0904mg frs/ml, which activity was very strong that was 1.53 times against WCME-7. However, the alkaloids, no action to T. Viennensis, were not active constitutes. 2.The activities of Wikstroemia chamedaphne against T. Viennensis eggs, nymph and adult were different variously, and the nymph was the most sensitive, which attributed probably to the mite structure and biochemical action. WCME-11 activity against female mite was 1.53 times against WCME-7, but WCME-11 activities against egg and nymph were lowered 38.05% and 40.38% respectively, which indicated that WCME-7 and WCME-11 have different active constitutes and actions. 3.WCME-7 and WCME-11 actions included stomach poison, controlling development, controlling reproducing etc. They were not only common nerve poison, they maybe have two different action mechanism: (1) affect nerve transmition; (2) affect the digest, growing system. WCME-11 showed more strong symptom phenomenon with more all-directions function method, knocked down more quickly. From 12 h, the mites began to enter death period on large. After treated in larva with WCME-7 and WCME-11, growth period showed longer, growth speed reduced obviously, particularly nymph period(â… ); Eggs per adult decreased, but the range of change was not obvious, compared with the degree of decreasing treated after adult period. WCME-11 appeared strong dispersal activity. The dispersal rate of 0.125 mg/ ml was 44.26%, which was the strongest. The peak of dispersal of the treat with 0.125 mg/ ml was before 24 h; but treats with 0.03 mg/ ml, 0.015 mg/ ml and 0.007 mg/ ml were all after 24 h.That is to say, because the peak of dispersal was in the time of highly-killing, WCME-11 above 0.06 mg/ ml would not raise the resurgence. 4. The WCME-11 could cause the fast reaction of the enzymes inside the mites. Before 8h, the enzymes were changed variely. WCME-11 could stir up to counteract poison such as GSTS and CarE, make mites declined poison through water solution, the group transfer etc.; But WCME-11 can restraint the target enzymes activity more strongly. For example Ca2+-ATP enzyme and AchE were important target enzymes, Specially at 12 h, the restraint degree of AchE suffered was biggest, and the mites enter death period on large. 5. The licorice could increase posion of WCME. The mixture of methyl alcohol extracts of Licorice root and WCME with 1:3 could make the WCME activity increased by 1.47 timeness.The mixture only need 42.01% of the total quantity to attaining the same result.
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