甜菜夜蛾对三种拟除虫菊酯杀虫剂的抗性稳定性研究

在室内脱离药剂选择的条件下,分别研究了甜菜夜蛾Spodoptera exigua Hübner 对氯氟氰菊酯、氰戊菊酯和顺式氯氰菊酯3种拟除虫菊酯杀虫剂的抗性稳定性及抗性衰退规律。结果表明,即使甜菜夜蛾对氯氟氰菊酯、氰戊菊酯、顺式氯氰菊酯的抗性分别达522.9倍、669.7倍和2 737.2倍,抗性仍不稳定,分别经10代、8代和9代饲养后抗性下降为60.8倍、90.8倍和180.5倍;对田间抗性种群的抗性衰退研究发现,甜菜夜蛾对这3种拟除虫菊酯的抗性也表现为不稳定性,在无杀虫剂选择的情况下,开始几代抗性下降较快,当下降至一定水平(6~10倍)后,抗性趋于基本稳定,但很难完全恢复对拟除虫菊酯的敏感性。

The Stability of Resistance to Three Pyrethroids in Spodoptera exigua Hübner

Regression of resistance to pyrethroids (cyhalothrin,fenvalerate,alpha-cypermethrin)in Spodoptera exigua Hübner following several generations of insecticide-free laboratory rearing was evaluated.Although laboratory selected Cyh-R、Fen-R and Cyp-R strain had high level resistance to cyhalothrin (522.9 fold),fenvalerate (669.7 fold)and alpha-cypermethrin (2 737.2 fold),the resistance was unstable and decreased to 60.8,90.8 and 180.5 fold respectively after 10,8 and 9 generations when selection was suspended.Studied on field-collected resistant strain showed that the resistance was also unstable,it declined rapidly without contact with the pyrethroids at first and then stablized at a 6~10 fold level.It seems that it is very difficult to recover susceptibility completely to the three pyrethroids.