小菜蛾过氧化氢酶和过氧化物酶与耐药性的关系

Correlation of catalase and peroxidase to pesticide tolerance in diamondback moth Plutella xylostella (L.)

毒力测定结果表明 ,小菜蛾幼虫对抑太保的耐药力 3龄是 2龄的 2 .65倍 ,4龄是 2龄的 4.0 7倍 .抑太保处理后 5 h,2、3、4龄幼虫过氧化氢酶 (CAT)活力均降至最低 ,分别为对照的 71 .9%、80 .9%和 90 .2 % ;处理后 1 0 -1 5 h,与对照相比 ,4龄幼虫 CAT活力上升程度最大 ,2龄最小 .H2 O2 由 0增加至 1 .1 7m L,CAT活力呈线性关系上升 .抑太保处理后 ,过氧化物酶 (POD)活力除 2龄幼虫在处理后 5 h下降 ,仅为对照的 65 .0 % ,3龄幼虫在处理后 1 h为对照的 99.2 %外 ,3个虫龄幼虫的 POD活力均高于对照 .H2 O2 由 0增加至 0 .1 m L,POD活力呈线性关系上升 .小菜蛾 2、3和 4龄幼虫的 CAT和

Catalase (CAT) and peroxidase (POD) were found to exist in the larvae of the diamondback moth Plutella xylostella (L.). Five hours after chlorfluazuron treatment, the activities of CAT in the larvae of three instars all decreased sharply, which were 71.9%, 80.9% and 90.2% of the control respectively. Ten and fifteen hours after treatment, the activity of CAT in the fourth instar larvae rose more than that in the other instar larvae. After treatment with chlorfluazuron to the larvae, the activities of POD in the larvae of three instars were all higher than the control, while the activities of POD in the second and third instar were only 65.0% and 99.2% of those in the control. The result indicated that the CAT and POD activities of diamondback moth showed correlation to the pesticide tolerance. Based on the results of toxicity test, it was clear that the pesticide tolerance of diamondback moth increased with larval instars. The lethal dosage of chlorfluazuron to larvae in the third and fourth instars were 2.65 and 4.07 times respectively, as compared with that in the second instar. The activities of CAT and POD were linear with respect to the quantity of H 2O 2 up to 1.17 and 0.1 mL respectively.