黄荆精油对玉米象的杀虫活性成分、毒力及作用机制

为明确黄荆精油及其主要成分作为储粮保护剂的开发利用价值，采用水蒸气蒸馏法从泰山黄荆Vitex negundo Linn.叶片中提取精油，利用GC-MS技术进行了成分分析鉴定，研究了黄荆精油及其主要成分桉树脑和α-蒎烯对玉米象 Sitophilus zeamais Motschulsky 成虫的毒力及作用机制。结果表明: 黄荆精油中含量大于0.3%的成分有31种，其中石竹烯、桉树脑和α-蒎烯的含量分别为35.97%，8.21%和0.69%。桉树脑、α-蒎烯和黄荆精油对玉米象成虫的综合杀虫毒力都较高，并以桉树脑的毒力最高，LC₅₀为0.7171 g·kg^-1；在2.0 g·kg^-1剂量下，桉树脑、α-蒎烯和黄荆精油对玉米象种群的抑制率分别达100％，85.45％和89.73％；3种药剂对玉米象72 h触杀LC₅₀分别为0.2690，0.7529 和0.2969 mg·cm^-2，毒力都很高；3种药剂在4 g·kg^-1剂量下，对玉米象的驱避率分别为96.49%，84.26％和90.61%，防虫作用大；3种药剂对玉米象72 h的熏蒸LC₅₀分别为14.053， 28.648 和21.429 μL·L^-1，熏蒸杀虫毒力较高，其中以桉树脑的毒力最高。3种药剂对玉米象有干扰呼吸的作用，对离体乙酰胆碱酯酶、过氧化氢酶和羧酸酯酶都有抑制作用。这些结果明黄荆精油及其主要成分的作用机制具有多样性。

Insecticidal components and toxicity of Vitex negundo (Lamiales: Verbenaceae) essential oil to Sitophilus zeamais (Coleoptera :Curculionidae) and their action mechanisms

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.