| Acute effects of Cd2+ and Cr6+ on detoxification enzymes and polyphenol oxidase（CarE, GST, ACP, AKP and PPO） in 5th instar nymphs of Oxya chinensis were studied under laboratory control condition. The results showed that CarE activities were activated after insects were exposed to the highest concentration of Cd2+（7.08 mg·kg-1） for 48 h and Cr6+（3.40 mg·kg-1） for 72 h, respectively. ACP activity was inhibited by Cd2+ at 96 h. AKP activity increased-in exposed to Cr6+ for 72 h. However, ACP activity increased at the lower concentration of 1.80 mg·kg-1 Cr6+ and declined at the higher concentration of 3.40 mg·kg-1 Cr6+ at 24 h and 48 h. GST activites were increased by Cd2+ at 48 h and by Cr6+ at 72 h and 96 h, respectively. PPO activities were decreased by Cd2+ at 24 h and by Cr6+ at 96 h, respectively. These results indicated that detoxification enzymes and polyphenol oxidase activity changed in response to toxic effects of heavy metal（Cd and Cr）, while the changes were related with the exposed dose and time of heavy metal. |
