中文摘要：

【目的】梨小食心虫Grapholitha molesta（Busck）是一种危害极其严重的果树害虫。中肠蛋白酶在昆虫生长发育过程中起着重要作用。本研究测定梨小食心虫幼虫中肠内蛋白酶活性的最适p H、蛋白酶抑制剂和激活剂对蛋白酶活性的作用,为利用蛋白酶抑制剂防治该害虫提供新思路。【方法】提取梨小食心虫3龄幼虫中肠液,利用酶专性底物测定各蛋白酶在3种不同缓冲溶液中的最适p H（dd H2O为对照）、蛋白酶抑制剂和激活剂对中肠蛋白酶活性的影响,同时测定饲喂蛋白酶抑制剂（PMSF,TLCK,TPCL和STI）后梨小食心虫中肠蛋白酶活性的变化。【结果】梨小食心虫幼虫中肠总蛋白酶在Tris-HCl,KH2PO4/Na OH和Glycine/Na OH 3种缓冲液中最适p H分别为10.5,11.0和11.0,强碱性胰蛋白酶的最适p H分别为10.5,11.0和11.0,弱碱性胰蛋白酶的最适p H分别为8.5,9.0和9.0,胰凝乳蛋白酶的最适p H分别为8.5,9.0和9.5。5种蛋白酶抑制剂（DTT,PMSF,TLCK,TPCL和STI）中,除TLCK对凝乳蛋白酶激活外,其他蛋白酶抑制剂对4种蛋白酶均表现为抑制,且浓度越大抑制效应越明显。抑制剂DTT对总蛋白酶和弱碱性胰蛋白酶的抑制效果高于其他抑制剂。4种蛋白酶激活剂（Mg Cl2,Ca Cl2,EDTA和EGTA）中,Mg Cl2抑制总蛋白酶和胰凝乳蛋白酶活性,而激活胰蛋白酶活性;Ca Cl2激活总蛋白酶和弱碱性胰蛋白酶活性,而抑制强碱性胰蛋白酶和胰凝乳蛋白酶,EDTA对4种蛋白酶均表现为抑制,EGTA除对强碱性胰蛋白酶表现为激活外,对另外3种蛋白酶表现抑制。用蛋白酶抑制剂PMSF,TLCK,TPCL和STI饲喂梨小食心虫幼虫,各抑制剂均可抑制4种蛋白酶活性,且在不同取样时间抑制水平不同。其中STI（50μg/m L）对4种蛋白酶的抑制效果高于其他抑制剂,且浓度越大抑制效应越明显。10,20和50μg/m L STI 3种浓度处理组,在取食后4 h时,4种蛋白酶活性升高,且上升程度与STI浓度有?

英文摘要：

【Aim】Grapholita molesta（ Busck） is a fruit pest that causes extremely serious damage. Intestinal protease plays an important role in its growth and development processes. To provide new ideas for using protease inhibitors to control pest insects,the effects of the optimum p H, different inhibitors and activators on the midgut protease activities of G. molesta larvae were studied in this study. 【Methods】Enzyme fluids were extracted from the midgut of the 3rd instar larvae of G. molesta. Using enzyme specificity substrates,the optimum p H of the midgut proteases of G. molesta larvae was detected in three different buffer solutions（ dd H2 O as the CK）,the effect of protease inhibitors and activators on the midgut protease activities were determined. At the same time, the effect of the different protease inhibitors（ PMSF,TLCK,TPCL and STI） on the midgut protease activities was also determined when G.molesta larvae were fed with them. 【Results】The optimum p H levels of midgut total protease of G.molesta larvae in the three buffers Tris-HCl,KH2PO4/ Na OH and glycine / Na OH were 10. 5,11. 0 and11. 0,respectively,those of high-alkaline trypsin were 10. 5,11. 0 and 11. 0,respectively,those of lowalkaline trypsin were 8. 5,9. 0 and 9. 0,respectively,and those of chymotrypsin were 8. 5,9. 0 and 9.5,respectively. Of the five protease inhibitors（ DTT,PMSF,TLCK,TPCL and STI）,except that TLCK activated the chymotrypsin activity,the other inhibitors inhibited the activities of all proteases; and the higher the inhibitor concentration was,the more significant the inhibitory effects were. The inhibition effects of the inhibitor DTT on the activities of total protease and low-alkaline trypsin were greater than those of the other inhibitors. Of the four protease activators（ Mg Cl2,Ca Cl2,EDTA and EGTA）,Mg Cl2 inhibited the activities of total protease and chymotrypsin but activated the trypsin activity, Ca Cl2 activated the activities of casein enzyme and low-alkaline trypsin but inhibited the activi