芫花活性成分抑制鳞翅目幼虫取食的机理

Effects of Yuan-hua Active Components on Digest Enzymes and GSTs of Two Lepidoptera Larvae

就芫花及其有效成分β-谷甾醇对斜纹夜蛾及卫矛尺蠖取食的抑制作用进行了研究.结果表明:斜纹夜蛾和卫矛尺蠖4龄幼虫连续4天取食涂有10%芫花乙醇粗提物(YAE)的食物后,其中肠淀粉酶、酯酶、蛋白酶的活力指数均显著高于对照;连续4天取食0.1%β-谷甾醇后,淀粉酶活力指数也显著高于对照,酯酶与蛋白酶的活力与对照持平.10%芫花乙醇粗提液处理斜纹夜蛾4龄幼虫4天,其谷胱甘肽-S-转移酶活性呈先升后降趋势,至第4天,活力绝对值虽高于对照组,但差异不显著.斜纹夜蛾4龄幼虫连续3代取食涂有芫花乙醇粗提物的食物后,其谷胱甘肽-S-转移酶活性呈先升后降的趋势,至F2代,与对照组的差异已不显著;以同样方法饲养5龄幼虫,其酶活性亦呈先升后降趋势,但每代处理与对照组的差异均不显著.芫花活性物质既抑制试虫取食,使其"收入"减少,又促进消化酶及解毒酶超量分泌,造成"支出"增加,最终导致虫体逐渐衰竭死亡.

The digest enzyme (amylase, esterase, proteinase) activity-indexes of the 4th-instar Spodoptera litura and Abraxas miranda larvae are all higher than that of the control after they have eaten the leaves treated with 10% of YAE for a continuous 4 days; when eaten the leaves treated with 0.1% of β-sitosterol for a continuous 4 days, the activity-index of amylase is significantly higher than that of the control, but the activity of amylase and proteinase are almost the same to the control. The activity of GSTs is increased much high than that of the control after the 4th-instar Spodoptera litura larvae eating the leaves treated with 10% of YAE for 4 days. After the 4th-instar Spodoptera litura larvae have eaten the leaves treated with YAE for 3 continuous generations, 4 days per generation, the activity of GSTs increases in F_0and F_1generation, and then decreases in F_2, to the level of the control. When the 5th-instar Spodoptera litura larvae are raised on the same condition for 3 continuous generations, the activity of GSTs firstly increases and then goes down, but the difference is not significant.