二点叶螨对甲氰菊酯、氧乐果和四螨嗪抗药性的选育、衰退和恢复

以兰州吐鲁沟公园的二点叶螨Tetranychus urticae 为敏感品系，分别用氧乐果、甲氰菊酯、四螨嗪喷雾处理15次，其抗性水平分别为38.5、479.8和67.3倍。将抗性品系分别与敏感品系进行杂交和回交的结果表明：抗氧乐果品系的显性系数DRS（R♀×S♂）为0.4700、D_SR（S♀×R♂）为0.4749；抗甲氰菊酯品系的DRS（R♀×S♂）为0.5155, DSR为0.5237；抗四螨嗪品系的DRS为0.3134, DSR为0.2466。表明二点叶螨对这3种药剂的抗性均是由单个不完全显性基因所控制。在连续10个月不接触药剂的情况下，3个抗性品系的抗药性都有下降，抗氧乐果品系的抗性下降最快，只有敏感品系的抗性倍数的3.6倍；抗甲氰菊酯种群的抗性下降较慢，为敏感品系的95.9倍。再经甲氰菊酯、氧乐果、四螨嗪分别连续15次喷雾处理后，3个抗性种群的抗性水平又再度回升，抗甲氰菊酯品系回升较快，抗性为敏感品系的523.5倍，抗四螨嗪品系次之，抗氧乐果的品系抗性恢复最慢。

Selection, decline and recovery of Tetranychus urticae Koch resistance to fen-propathrin, omethoate and clofentezine

After the susceptible strains of Tetranychus urticae were sprayed with omethoate, fenpropathrin, clofentezine for 15 times, their resistance to these insecticides increased 38.5, 479.8 and 67.3-fold respectively. Cross and backcross breeding between the resistant and the susceptible strains showed that the dominance coefficient (D) of the R-omethoate strain was RS=0.4700 and SR=0.4797; D of the R-fenpropathrin strain was RS=0.5155 and SR=0.5237; D of the R-clofentezine strain was RS=0.2466 and SR=0.3134. It was inferred that their resistance to the insecticides was controlled by a single and incomplete dominant gene. The resistance of three strains significantly declined when spraying was suspended for 10 months, and following spraying for fifteen successive times with the 3 insecticides respectively resulted in recovery of their resistance to the corresponding insecticide to different extents.