家蝇对两种拟除虫菊酯类杀虫剂抗性的稳定性

目的 评估家蝇种群对拟除虫菊酯类杀虫剂抗性的稳定性。方法 在连续使用拟除虫菊酯类杀虫剂多年的内蒙古赤峰市屠宰场采集家蝇自然种群，带回实验室饲养并测定其对氯氰菊酯和溴氰菊酯LD50的变化情况。结果 家蝇连续用氯氰菊酯选择10代，相对抗性上升了49．96倍，LD50是敏感品系的1412．75倍。自然种群家蝇脱离用药环境后，对氯氰菊酯的抗性衰减较为缓慢，30代仍不能恢复敏感性；而对溴氰菊酯的抗性衰减不明显，至12代时仍保持223．36倍的抗性。结论 家蝇对氯氰菊酯抗性上升较快，对氯氰菊酯和溴氰菊酯抗性衰减缓慢。

Stability of Two Kinds of Pyrethroids Resistance in Housefly(Diptera: Muscidae)

Objective To assess the stability of pyrethroids resistance in population of housefly(Musca domestica). Methods Houseflies were collected from a slaughterhouse in Chifeng of Inner Mongolia, where pyrethriod pesticides being used continuously for many years. This population was taken to laboratory to be cultured and then its resistance to cypermethrin and deltamethrin was tested. Results The results showed that:1) after selected under cypermethrin for 10 generations, the relative resistance raised to 49.96 folds, and its LD_ 50 was 1 412.75 folds of that of the sensitive population.2) attenuation of the resistance to cypermethrin in the houseflies got lower and could not resume sensitivity until F_ 30 without insecticide selection. At the same time the sample was used to do another test, the results showed that the attenuation of resistance to deltamethrin was not obvious and LD_ 50 in F_ 12 was 223.36 folds of that of the sensitive population. Conclusion The resistance to cypermethrin in housefly increased rapidly and the attenuation of resistance to cypermethrin and deltamethrin was slow.