Abstract:

In order to study the insecticidal activity components and preliminary mechanism of the petroleum ether extract from Artemisia annua against Mythimna separata， the insecticidal activity of different fractions and main components were measured by insect immersion method. The petroleum ether extract was separated by column chromatography and analyzed by gas chromatography-mass spectrometry to determine its chemical components， and the target enzyme and metabolic enzyme activities in the body of Mythimna separata were measured for the active components. The results showed that the petroleum ether extract of Artemisia annua was separated by silica gel column chromatography， and 27 fractions were obtained， of which fraction 8 showed the best contact toxicity. According to gas chromatography-mass spectrometry， the main compounds were tridecane， 4-quinolinecarboxaldehyde， caryophyllene oxide， linoleic acid ethyl ester， linolenic acid ethyl ester with contents of 7.9%， 72.8%， 3.6%， 2.4%， 3.1%，respectively. The lethal concentration of 50% （LC₅₀） of above 5 compounds on the 7th day were 7.9， 2.5， 3.6， 5.4 and 1.5 mg·mL^-1， respectively， which indicated that ethyl linolenic acid had significant contact toxicity against M. separata. On the 7th day of treatment with 1.5 mg·mL^-1 linolenic acid ethyl ester， the scanning electron microscopy results showed that the wax layer structure in the surface of M. separata were loosely， the wax layer particles disappeared significantly， and the wax flower gap increased. And the acetylcholinesterase （AChE） and carboxylesterase （CarE） of M. separata treated with 1.5 mg·mL^-1 linolenic acid ethyl ester showed first activation and then inhibition， Na⁺-K⁺-ATPase showed inhibition over time， and catalase （CAT） showed first inhibition and then activation. To sum up， the linolenic acid ethyl ester was the main active compound of A. annua，which provided reference for the development of new plant-based insecticides and biological control of M. separata and the development and utilization of A.annua resources.

Key words: Artemisia annua, Mythimna separate, linolenic acid ethyl ester, mechanism

摘要：

为研究黄花蒿石油醚萃取物对粘虫3龄幼虫杀虫活性成分及初步作用机制，采用硅胶柱色谱进行分离，气相-质谱法分析化学成分，浸虫法测定不同馏分及主要成分的触杀活性，并进一步对活性成分进行粘虫幼虫体内靶标酶和代谢酶活性测定。结果表明，黄花蒿石油醚萃取物经硅胶柱色谱分离，共得到27个馏分，其中馏分8表现出较好的触杀活性。经气相色谱-质谱法检测，十三烷、4-喹啉甲醛、石竹烯氧化物、亚油酸乙酯和亚麻酸乙酯为主要化合物，含量分别为7.9%、72.8%、3.6%、2.4%、3.1%。这5种化合物处理粘虫7 d的半数致死浓度（LC₅₀）分别为7.9、2.5、3.6、5.4和1.5 mg·mL^-1，即亚麻酸乙酯对粘虫的触杀活性最好。扫描电镜结果显示，1.5 mg·mL^-1亚麻酸乙酯处理粘虫7 d，粘虫表皮蜡质层结构排列疏松，蜡质层颗粒明显消失，蜡花间隙增大；在处理过程中，粘虫的乙酰胆碱酯酶和羧酸酯酶表现出先激活后抑制作用；Na⁺-K⁺-ATPase表现出持续抑制作用；过氧化氢酶表现出先抑制后激活作用。综上，亚麻酸乙酯为黄花蒿对粘虫杀虫活性的主要化合物，研究结果为黄花蒿资源的开发利用以及将亚麻酸乙酯作为生物防治粘虫的潜力化合物提供参考。

关键词: 黄花蒿, 粘虫, 亚麻酸乙酯, 作用机制