3种植物次生代谢物质对舞毒蛾的杀虫活性分析

为探究苦参碱、氧化苦参碱和山奈酚对舞毒蛾3龄幼虫的杀虫活性以及杀虫机理，本研究通过生物测定、离体和体内酶活性实验，分析了上述3种植物次生代谢物质对舞毒蛾的杀虫效果及对其谷胱甘肽S-转移酶(GST)、乙酰胆碱酯酶(AChE)和羧酸酯酶(CarE)活性的影响。实验结果表明:苦参碱、氧化苦参碱和山奈酚均对舞毒蛾3龄幼虫有良好的杀虫效果，其中苦参碱杀虫效果最强，致死中质量浓度(LC₅₀)为0.420 mg/mL；离体酶活性实验发现，3种植物次生代谢物质对舞毒蛾离体GST、AChE和CarE活性均有抑制效果，其中氧化苦参碱对GST和AChE抑制作用最强，抑制中质量浓度(IC₅₀)分别为0.928和0.717 mg/mL，而苦参碱对CarE抑制作用最强，IC₅₀为0.436 mg/mL；而体内酶活性实验结果显示，苦参碱对GST抑制作用最强，在处理后48 h，GST活性达到最低，仅为同时期对照组的39%；而氧化苦参碱对AChE和CarE抑制作用最强，在处理后72 h，AChE和CarE活性最低，分别为对照组的44%和40%。以上结果表明苦参碱、氧化苦参碱和山奈酚对舞毒蛾幼虫GST、AChE和CarE活性的抑制作用是其具有杀虫活性的原因之一。 

Insecticidal activity analysis of three plant secondary metabolites on Lymantria dispar

In order to investigate the insecticidal activity and mechanism of matrine, oxymatrine and kaempferol on 3rd instar larvae of Lymantria dispar, the effects of three plant secondary metabolites on the survival and three enzymes ( GST, AChE and CarE) of L. dispar were analyzed by bioassay, in vitro and in vivo enzyme activity assay. The results indicated that matrine, oxymatrine and kaempferol all possessed a highly insecticidal activity on 3rd instar larvae of L. dispar, and matrine showed the highest insecticidal activity among three plant secondary metabolites with a LC50 value of 0. 420 mg/mL. In vitro enzyme activity assays showed that the activities of GST, AChE and CarE could be inhibited by three plant secondary metabolites. The IC50 values of oxymatrine against GST and AChE were 0. 928 and 0. 717 mg/mL, respectively, while the IC50 value of matrine against CarE was 0. 436 mg/mL, which was the highest inhibition. Furthermore, the results of in vivo enzyme activity assay indicated that matrine had the highest inhibition on GST, which showed the lowest activity at 48 hours after treatment and was 39% of the control at the same stage. Moreover, oxymatrine had the highest inhibition on AChE and CarE, and their activities were 44% and 40% of the control at 72 hours after treatment, respectively. The above results indicate that the inhibition of matrine, oxymatrine and kaempferol on three enzymes ( GST, AChE and CarE) of L. dispar is one of the reasons for their insecticidal activity.