中文摘要：

本试验以4龄小菜蛾体内海藻糖酶为研究对象，研究了其酶学特性以及四种常用杀虫剂在离体条件下对其活性的影响。结果表明，小菜蛾体内海藻糖酶的最适反应pH为6.0，温度50℃，其米氏常数（Km）为（12.57±0.99）mmol/L，最大反应速度（Vm）为（0.775±0.04） mmol/（min？g pro）。在药剂浓度为40mg/L时，四种杀虫剂（丙溴磷、灭多威、仲丁威和多杀霉素）对4龄幼虫海藻糖酶活性均有不同程度的抑制作用，其抑制率分别为25.83%、20.19%、18.99%和18.62%；而且随着药剂浓度的增加，上述四种杀虫剂对小菜蛾海藻糖酶活性的抑制率也逐渐增大。

英文摘要：

The characteristics of trehalase in Plutella xylostella （Linnaeus） and inhibitory effect of four insecticides on trehalase activity of the 4th instar larvas were studied. The results obtained from experiments in vitro indicated that the optimum pH value of trehalas was 6.0, and the optimum temperature was 50℃. The Michaelis constant （Km） of trehalase hydrolyzing trehalose was （12.57±0.99）mmol/L. The maximum velocities （Vmax） hydrolyzing trehalose was （0.775±0.04）mmol/（min ？g pro）. At the 40mg/L of insecticides （profenofos, methomyl, fenobucarb and spinosad）, there are different inhibitory effects on trehalase in 4th instar larvas of Plutella xylostella, their percentages of inhibition to trehalase activity were 25.83%, 20.19%, 18.99% and 18.62% respectively. Their inhibitory effects on trehalase activity were enhanced with the increasing of insecticide concentrations.