茚虫威对不同抗药性品系小菜蛾呼吸代谢的影响

以小菜蛾Plutella xylostella(L.)敏感品系(S)、田间品系(F)及茚虫威汰选抗性品系(T17)幼虫为供试虫源,采用便携式光合作用测定仪测定小菜蛾3～4龄幼虫在受药前后或不同受药剂量等条件下呼吸速率的变化,从能量代谢的角度研究抗药性机制。结果表明,汰选抗性品系、田间品系与敏感品系同龄期小菜蛾幼虫在未受药条件下的呼吸速率差异不显著,表明抗药性的产生并未影响小菜蛾本底的呼吸速率。以各个品系的茚虫威LC20和LC50剂量处理幼虫后,3个品系的呼吸速率均明显提高,汰选抗性品系呼吸速率提高幅度明显大于其他2个品系。在LC20剂量下3个品系呼吸速率峰值均出现在2h前后,10h后恢复到正常水平;在LC50剂量下敏感品系没有明显差异;而田间品系和汰选抗性品系分别在药剂处理后4h和6h达到呼吸高峰,汰选抗性品系保持高水平呼吸速率时间长达9h,分别于药后15h和24h恢复到正常水平。这表明用药后抗性品系呼吸速率的提高幅度与小菜蛾的解毒代谢能力有关,这也揭示了昆虫幼虫中毒后能量消耗会随着抗性水平的提高而增加。

Effects of indoxacarb on the respiratory metabolism of different resistant strains of Plutella xylostella

The effects of indoxacarb on the respiratory rates of 3—4 instar larvae of a susceptible strain （S）,a field population （F）,and a resistant strain（T17） of Plutella xylostella （L.） were investigated.The results show that there were no significant differences in respiratory rates of larvae of the same instar among the three strains,and that increased resistance to indoxacarb did not change the fundamental respiratory rate.The respiratory rates of larvae from all three strains increased significantly with increasing indoxacarb dose.However,the respiratory rate of the T17 strain was higher than that of the S and F strain at their respective LC20 and LC50 doses.The highest respiratory rate of all three strains appeared 2 h after treatment after which it took 10 h for larvae to return to the initial respiratory rates observed at their respective LC20 dosages.There were no significant differences in the respiratory rate of the susceptible strain between LC20 and LC50 doses.However,the highest respiratory rates observed in the field population and resistant strain appeared at 4 h and 6 h after treatment,respectively.The resistant strain sustained the maximum respiratory rate for 9 h.It took 15 h and 24 h respectively for the field population and the resistant strain to return to their initial respiratory rates.This suggests a degree of correlation between increased respiratory rate and the ability to detoxify indoxacarb in Plutella xylostella （L.） larvae.These results indicate that the energy consumption of treated larvae increases with indoxacarb resistance level.