马尾松毛虫过氧化氢酶及过氧化物酶与耐药性的关系

马尾松毛虫Dendrolimus punctatus幼虫体内存在着过氧化氢酶(CAT)和过氧化物酶(POD)。4龄幼虫的CAT和POD活力较大，其次是6龄幼虫，5龄幼虫的CAT和POD活力较4龄和6龄幼虫低。醚菊酯(etofenprox)处理后，在兴奋期(30 min)，CAT和POD活力水平上升。4龄和6龄幼虫在抑制期(50 min以后)，CAT和POD活力呈波动式上升，接近死亡时下降。5龄幼虫的CAT和POD活力呈波动式上升，接近死亡时下降。5龄幼虫的CAT在抑制期保持比正常虫体高的活力。结果表明，马尾松毛虫4龄、5龄和6龄幼虫与耐药性存在一定的相关性，研制酶的抑制剂具有实用意义。根据毒力测定结果，马尾松毛虫幼虫对醚菊酯的耐药力，5龄是4龄的1.43倍，6龄是4龄的1.72倍。因此，药物防治的合理时期应掌握在4龄以前较适宜。

Correlation of catalase and peroxidase with pesticide tolerance in massonpine caterpillar

Catalase(CAT) and peroxidase(POD) were found to exist in the larvae of Dendrolimus punctatus Walker. The activity of CAT and POD in the fourth and sixth instar larvae were found to be higher than that in fifth instar larvae. After treatment with etofenprox to the larvae, the enzyme activity of D.punctatus showed correlation with tolerance to the pesticide. The activity of CAT and POD increased during exciting stage. Based on the results of toxicity test, it was clear that the pesticide tolerance of massonpine caterpillars increased with larval instars. The lethal dosage of etofenprox to larvae in the fifth and sixth instars increased by 43% and 72% respectively,as compared with that in the fourth instar. It will be rational to carry out chemical control before the larvae being in fourth instar.