Abstract: Volatile oils were obtained from the flowers of Michelia alba DC.by means of steam distillation technique.The volatile components in the extracts were analyzed by GC-MS and their relative contents were identified by peak area normalization method.The results showed that there are 76 identified compounds which include 37 terpenoids,17 alcohols,6 alkane compounds and other substances in the essential oils.The relative contents of all detected compounds in the essential oils are 93.026%.In addition,we conducted antimicrobial experiments with different strains,and explored the antifeedant properties of essential oils in different concentrations against the worm Mythimna separata.The experimental results showed that the extraction rate was 4.18% by using steam distillation extraction method.The most abundant component of the extracted oil is linalool.The essential oils showed most potent inhibitory activity against Xanthomonas oryzae and Bacillus subtilis among the tested strains and it had a good inhibitory effect on the armyworm Mythimna separata.

Key words: Michelia alba DC., volatile oil, antifeedant, GC-MS, antimicrobial activity, Mythimna separata