| Citrus medica L.var sarcodactylis(Noot.)Swingle is a plant of the genus Citrus,which has been limited to indoor appreciating and agricultural products for years with low added value.The similarity of chemical composition among citrus extracts and the exploration of the bioactivities of citrus extracts in the fields of pharmacy and medicine which have been proved to replace chemical synthetic active substances enlightened the study on the bioactivity of C.medica.In this study,the C.medica essential oil was extracted by distillation,mechanical-pressing and supercritical CO2 extraction,and the acaricidal and repellent activity of C.medica oil on Tetranychus cinnabarinus and Dermatophagoides farina Hughes were explored.Firstly,distillation,mechanical-pressing and supercritical CO2 extraction were adopted to prepare C.medica oil.GC-MS was employed to identify the chemical constituents of C.medica oil obtained by the three extraction methods.The major components were monoterpenes and the highest content component was d-limonene(42.30-47.23%).The remainders were sesquiterpenes,monoterpene alcohols,sesquiterpene alcohols,aldehydes,esters and ketones.It is mainly characterized by that the content of alcohols and aldehydes in the steam distillation oil is slightly higher than that of the pressed oil and the CO2 extracted oil.The acaricidal activity of C.medica oils was evaluated by contact and fumigant bioassays.The results showed that the three essential oils exhibited similar toxicity against T.cinnabarinus(LC50=66.70-81.09?L m L-1 in contact assay;LC50=30.88-38.10?L L-1 air in fumigant assay).The toxicity of the distilled oils is the strongest among the three oils.The acaricidal activity of some major components were evaluated with the results showing that the lethal toxicity of d-limonene(LC50=63.07?L m L-1 in contact assay;LC50=31.07?L L-1 air in fumigant assay)and that of three oils were the most desirable.The knockout experimental model was introduced to evaluate the contribution of components to the acaricidal activity of the essential oils.The results showed that under the conditions of contact and fumigation,the most significant contribution of components to acaricidal effect was d-limonene,followed by bisabolene,geraniol and linalool.The synergistic acaricidal activity of d-limonene,?-pinene,?-pinene and bisabolene was evaluated.The results showed that the best components of the synergistic acaricidal activity in contact and fumigant asssays were d-limonene and ?-pinene,respectively.The verification experiment showed that the concentration of d-limonene and ?-pinene in the essential oil was appropriately increased within the acceptable range of the aroma,and the contact and fumigation LC50 of the oil was reduced to 56.25 ?L m L-1 and 22.72 ?L L-1 air.The repellent activity of the essential oil and d-limonene against T.cinnabarinus was studied.The results showed that at 40?L m L-1 concentration,the best repellent effect at 2h and 4h observation period were the distilled oil and d-limonene(PR=67.5±12.58% and 65.0±12.91%,respectively).Additionally,the textile anti-mites evaluation was used to evaluate the lethal toxicity of the essential oil compounded with d-limonene against D.farina.The results showed that the cotton cloth impregnated with the essential oil had a knockdown rate of 43% on mites at 30 min,and the mortality of D.farina treated with oil was 20% at 72 hours.C.medica essential oil was used as raw material to develop a series of products with acaricidal and repellent effects,including sachet,diffuser,air freshener,shampoo,body wash,body lotion,soap,aromatherapy essential oils,etc.The research results have a certain reference value and practical application guiding significance for further industrialization of C.medica products and improving the added value of the products.At the same time,it is of great significance to expand the new application fields of C.medica oil and increase the income of fruit farmers. |
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