棉铃虫对拟除虫菊酯抗性稳定性研究

研究棉铃虫Helicoverpa armigera (Hubner)对三种拟除虫菊醌（氰戊菊酯、溴氰菊酯、功夫菊酯)的抗性稳定性及敏感性恢复表明，即使棉铃虫对氰戊菊酯的抗性达到3166.3倍以上，抗性仍不稳定，经14代室内饲养后抗性下降为61.4倍；对一系列田间抗性种群的抗性稳定性研究后发现，棉铃虫对这三种拟除虫菊酯的抗性不稳定，在没有杀虫剂选择的情况下，开始几代抗性下降较快，当下降到一定水平(2～9倍)后，抗性比较稳定，很难完全恢复对拟除虫菊酯的敏感性。

STABILITY OF PYRETHROIDS RESISTANCE IN HELICOVERPA ARMIGERA (HUBNER)

Regression of pyrethroids resistance in Helicoverpa armigera (Hubner)following several generations of insecticide-free laboratory rearing was evaluated.Although laboratory selected Fen-R strain had extremely high level resistance to fenvalerate (3 166.3 fold), the resistance was unstable and decreased to 61.4 fold after14 generations when selection was suspended. Studies on several field-collected cotton bollworms resistant to pyrethroids (fenvalerate, deltamethrin & cyhalothrin) showed that their resistance was also unstable; it declined rapidly without contact with the pyrethroids at first and then stablized at a 2- 9 fold level. It seemed very difficult to recover susceptibility completely to the three pyrethroids.