Abstract:Plant volatile organic compounds (VOCs) play a crucial role in the defence of insect pests. In this study, the VOCs components of Cupressus funebris under healthy and insect (Chinolyda flagellicornis)-damaged conditions were measured and analyzed at Forest Farm of Changjiang River, Chongqing. VOCs analysis before the occurrence of insect pest showed that 37 components were identified in both samples, the main component is terpenoids and the followings are phytols, esters, aldehydes, alkanes, etc.; Among them, borneol is specific to the healthy C.funebris, while (Z)-2-decena is to the damaged ones, the rests are presented in both but different in the concentrations. After the occurrence of insect pest, 32 components were identified in both samples, however, the other 5 components, borneol, (Z)-2-decenal, menthol, naphthalene and alpha-caryophyllene, had not been detected. Moreover, most of the detected ones had the contrary trends in the changes of concentrations to the results before the occurrence of insect pest. The results suggested that the difference of VOCs emission in the healthy and the damaged C.funebris is one of the important mechanisms of C.funebris defending insect pest, which would be a desirable trait and index for the selection and breeding of C.funebris against C.flagellicornis.