杠柳杀虫组分F3-28对东方粘虫和小地老虎幼虫中肠消化酶活性的影响

F3-28是从杀虫植物杠柳Periploca sepium Bunge根皮中分离的一个具有杀虫活性的馏分，其主要成分为杠柳苷A、杠柳苷E和杠柳苷X。为了探索F3-28的初始作用部位， 为深入研究其作用机理奠定基础， 本研究采用经典的昆虫消化酶活性测定方法， 比较了F3-28对小地老虎Agrotis ypsilon和东方粘虫Mythimna separata 5龄幼虫消化酶系活性的影响。结果表明：对F3-28不敏感的小地老虎幼虫摄食F3-28后，其中肠蛋白酶、淀粉酶、脂肪酶的活性无显著变化。对F3-28敏感的东方粘虫幼虫摄食F3-28后2，4，8，10，12，24，48 h， 其中肠总蛋白酶活性分别为对照组的0.76，2.53，1.45，1.88，1.54，1.46，1.70倍，且和药物浓度呈依赖关系； 类胰蛋白酶的活性分别为对照组的1.60， 1.75，1.60，1.12，1.39，1.16，1.15倍（以BAPNA为底物）或1.68，1.95，1.53，1.26，1.15，1.13，1.14倍（以TAME为底物），且和药物浓度呈依赖关系； 类胰凝乳蛋白酶活性分别为对照组的0.50，1.66，1.44，1.18，1.54，1.08和1.03 倍，但和药物浓度无依赖关系； 淀粉酶的活性分别为对照组的1.60，1.35，1.27，1.31，1.23和1.20 倍，但和药物浓度无依赖关系；对脂肪酶活性无明显影响。这些结果说明，杠柳杀虫活性组分F3-28的作用机理可能涉及对试虫中肠蛋白酶的激活，特别是对类胰蛋白酶的激活。

Effects of insecticidal fraction F3-28 from Periploca sepium on the activities of digestive enzymes in the midgut of larvae of Mythimna separata and Agrotis ypsilon(Lepidoptera:Noctuidae)

 F3-28 is an insecticidal fraction which was isolated from the extract of Periploca sepium bark.  In order to understand the action mechanism of the insecticidal fraction F3-28, the effects of F3-28 on the activities of proteases, trypsin-like protease, chymotrypsin-like protease, lipase and amylase in the midgut of the 5th instar larvae of Mythimna separata and Agrotis ypsilon were studied. The results showed that after A. ypsilon larvae which are insensitive to F3-28 ingested this fraction, the activities of proteases, lipase and amylase in the midgut changed indistinctly. However, after M. separata larvae which are sensitive to F3-28 ingested this fraction, at 2, 4, 8, 10, 12, 24 and 48 h post treatment their midgut protease activity was 0.76, 2.53, 1.45, 1.88, 1.54, 1.46 and 1.70 times as high as that of the control, respectively, and their midgut trysin-like protease activity was 1.60, 1.75, 1.60, 1.12, 1.39, 1.16 and 1.15 times （BAPNA as the substrate） and 1.68, 1.95, 1.53, 1.26, 1.15, 1.13 and 1.14 times (TAME as the substrate ) as high as that of the control, respectively. Similarly, after M. separata larvae ingested F3-28, at 2, 4, 8, 10, 12, 24 and 48 h post treatment their midgut chymotrypsin-like protease activity was 0.50, 1.66, 1.44, 1.18, 1.54, 1.08 and 1.03 times as high as that of the control, respectively, and their midgut amylase activity was 1.60, 1.35, 1.27, 1.31, 1.23 and 1.20 times as high as the control, respectively. The increase in activities of proteases and trysin-like protease in the midgut was dependent on the concentration of F3-28, but that of chymotrypsin-like protease and amylase in the midgut was not. After M. separata larvae ingested F3-28, their midgut lipase activity changed inconspicuously. These results imply that the insecticidal mechanism of F3-28 may be related with the activation of proteases, especially trypsin-like protease, in the larval midgut.