夜蛾斯氏线虫对菜青虫几种保护酶活力的影响

为探索昆虫病原线虫对菜青虫保护酶活力的影响，分别用10、50、100头夜蛾斯氏线虫（Steinernema feltiae）侵染4龄菜青虫（Pieris rapae），对侵染后菜青虫体内超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）的活力变化进行了研究。结果表明，接入线虫后，菜青虫的SOD活力显著上升。16 h时各处理的SOD活力均达到最大值，10、50、100头线虫处理的菜青虫SOD活力分别为44.266 7、49.866 7、68.033 3 U/g，均显著高于对照的35.033 3 U/g（p<0.01或p<0.05），3种线虫剂量处理之间也存在显著差异（p<0.01或p<0.05）。POD的活性在接虫后8 h各处理均显著高于对照（p<0.05），酶活性随侵染线虫数量的增加而增大，到24 h以后酶的活性开始显著下降，线虫剂量越大下降越快。CAT活力在处理后均显著上升，16~32 h各处理均维持在较高的水平，32 h以后开始显著下降。这反映出菜青虫在昆虫病原线虫侵染初期防御能力增强，16~32 h以后防御能力显著下降。

Changes of the activities of protective enzymes in Pieris rapae infected by Steinernema feltiae

To explore the change in protective enzymes in Pieris rapae infected by entomopathogenic nematodes, the 4th instars of P. rapae were separately infected by 10, 50 and 100 Steinernema feltiae in Gansu, and SOD, POD and CAT activities of the infected P. rapae were detected at different times. The results showed that the SOD activity of the infected P. rapae increased significantly. The activity of the infected SOD reached the maximum at the 16th hour and the SOD activity of the P. rapae infected by 10, 50, 100 S. feltiae was 44.266 7, 49.866 7 and 68.033 3 U/gFW, respectively, which were all significantly higher than the control (p<0.01 or p<0.05). Significant differences between different treatments were observed (p<0.01 or p<0.05). The activity of POD was significantly (p<0.05) higher than the control at the 8th hour and increased with the growing number of S. feltiae. At the 24th hour, the activity of POD declined significantly. With time going on, the activity of CAT increased significantly after the P. rapae was infected for 16-32 hours, each at high level. However, the activity of CAT declined after 32 hours. It is suggested that the defense system of P. rapaes was enhanced at initial period, but dropped sharply after 16-32 hours.