| Phytophagous pest mites are one of the important organisms which seriously harmful to our agricultural and forestral production. In order to meet the need of organic cultivation and to face continued problems of chemical insecticides, the development and preparation of botanical insecticide and acaricide, which base on natural secondary metabolites of plants, has become the hot spot in internal and abroad investigation domains. Stellera chamaejasme L. was selected as potential resources to develop botanical acaricide. In comparison with other plant resources, the advantages of S. chamaejasme are much quantity and broad and higher biomass. The multipurpose utilization of S. chamaejasme, especially in pesticide, is not only its success in ecological reservation, but also its plant-based botanical insecticide development.In this research, with using the advanced method of extraction and separation in traditional Chinese medicine, a compound IV was obtained from roots of S. chamaejasme by preparative MPLC and HPLC. The structure of compound IV was established as scopoletin by analysis of NMR and IR data. And then the laws of acaricide effect and lethal mechanism of scopoletin were studied. The effects of mites control in strawberries and physiological response of strawberries, which were treated by scopoletin, were also investigated in this study. The main results and conclusion are as follows.(1) Scopoletin is an important acaricidal substance in Stellera chamaejasme L.. In this study, the purity of scopoletin after purification is up to 97.756%. There was no significant difference of acaricidal effects between natural and standard scopoletin.(2) The acaricidal toxicity and death dynamic variation of scopoletin treatments anaylized by Time-Dose-Mortality (TDM) model and S-shaped cure showed that the contact toxicity of mean lethal concentrations (LC50) is 1.243 mg·mL-1 (Probit,24 h) or 1.346 mg·mL-1(TDM); the systemic toxicity of LC50 is 7.231 mg·mL-1 (Probit,24 h) or 8.143 mg-mL-1 (TDM). The lethal rate of scopoletin was higher than pyrethrin, and the scopoletin contact treatment had the highest lethal rate.(3) Scopoletin is a neurotoxin. The mechanism of acaricidal substance is scopoletin can significantly inhibit the activities of AChE, and the inhibition can lead to increasing of ACh, which can block nerve conduction. Scopoletin can also significantly inhibit the activities of Na+-K+-ATPase, and then increase of K+ in cell, which can lead to cell broken caused by excessive absorb water. The MAO and Ca2+-Mg2+-ATPase were also inhibited by scopoletin.(4) The optimum time of applying acaricide was within 12 days after the spider mites occurrence. The optimal concentration of acaricide was 3 mg·mL-1, while the 9 mg·mL-1 treatment has perfect control.(5) Scopoletin is generally safe to strawberries. The determining quotas of physiological response of strawberries were able to return to the normal level. All different concentration treatments (3 to 9 mg·mL-1) can increase relative conductivity and MDA content of leaves during the initial post-period, while the specific activities of SOD and CAT rose. But all indicators gradually returned to the normal level in 150 h. The dynamic changes of chlorophyll content and net photosynthesis rate were similarly during the whole treatment period.
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