关键词: 玉米象, 黄荆, 精油, 桉树脑, α-蒎烯, 毒力, 杀虫机理

Abstract: To determine the development and utilization value of Vitex negundo Linn. as grain protectant, this study focused on the component analysis, toxicity, mode of action and action mechanism of essential oil of V. negundo, which was extracted using steam distillation. The GC-MS method was used to analyze the components of essential oil. The results showed that there were thirty-one components whose content was more than 0.3% in the essential oil of V. negundo. The main components were caryophyllene, eucalyptol and α-pinene, with contents of 35.97%，8.21% and 0.69％, respectively. Eucalyptol, α-pinene and V. negundo essential oil all had high overall toxicity to the adults of Sitophilus zeamais in 72 h of treatment and the highest one was eucalyptol, whose LC50 was 0.7171 g·kg^-1. They also could control F₁ population effectively. At the dosage of 2.0 g·kg^-1，the inhibitory rates of eucalyptol, α-pinene and V. negundo essential oil to S. zeamais were 100%, 85.45％ and 89.73％, respectively. The LC₅₀ values of eucalyptol, α-pinene and essential oil of V. negundo to S. zeamais in the contact toxicity were 0.2690, 0.7529 and 0.2969 mg·cm^-2, respectively; and at the dosage of 4 g·kg^-1，they all exhibited distinctly repellent effects and the repellency rates were 96.49%，84.26％ and 90.61%, respectively. The LC₅₀ values to S. zeamais were 14.053, 28.648 and 21.429 μL·L^-1 fumigated by eucalyptol, α-pinene and essential oil of V. negundo for 72 h, respectively. They all showed high fumigation effects, of which eucalyptol had the highest one. The essential oil of V. negundo, and its main components eucalyptol and α-pinene all affected the breath of S. zeamais. The three samples distinctly inhibited the activities of AChE, CAT and CarE of S. zeamais in vitro. All the results suggest that the action mechanisms of essential oil and main components of V. negundo show the characteristics of diversity.

Key words: Sitophilus zeamaise, Vitex negundo, essential oil, eucalyptol, α-pinene, toxicity, action mechanism