【目的】 通过抗药性监测掌握滇中通海和滇西弥渡菜区小菜蛾Plutella xylostella (L.)种群对3种生物农药的抗药性水平及其变化趋势，为抗性治理提供技术支持。【方法】 2008—2015年，在室内采用浸叶法测定了云南两个菜区小菜蛾种群对阿维菌素、多杀菌素和苏云金杆菌的抗药性。【结果】 2008年抗药性测定结果表明，滇中通海、滇西弥渡菜区小菜蛾对阿维菌素和多杀菌素的抗药性水平均为高抗，对阿维菌素LC₅₀值分别34.017和25.688 mg/L，抗性倍数为1 700.85和1 284.40倍；对多杀菌素LC₅₀值分别13.728和19.830 mg/L，抗性倍数为114.40倍和165.25倍，两菜区对多杀菌素的抗性也为高抗；两菜区小菜蛾对苏云金杆菌敏感，LC₅₀值分别0.530和0.538 mg/L，抗性倍数为2.04倍和2.07倍，属于抵抗水平。到2015年，通海和弥渡菜区小菜蛾种群对阿维菌素的抗性倍数分别下降到了455.70倍和255.05倍，下降趋势显著，但两菜区仍属高抗水平；对多杀菌素的抗药性下降趋势不显著，抗性倍数分别为35.56倍和75.28倍，为中抗水平，但年度间变化幅度较大，LC₅₀为0.885~19.830 mg/L；两菜区对苏云金杆菌仍敏感，抗性倍数分别为5.41倍和1.73倍。【结论】 总体上，2008—2015年度间有差异，通海和弥渡菜区小菜蛾种群对3种药剂的抗药性基本一致，对阿维菌素和多杀菌素的抗药性有所下降，但仍处于高抗水平，对苏云金杆菌一直保持在抵抗水平，建议生产上可以轮换使用苏云金杆菌，以提高对小菜蛾的持续控制效果。

      [Objectives]  To understand trends in insecticide resistance in the diamondback moth, Plutella xylostella (L.), and the population dynamics of this species, in Tonghai and Midu counties, which are the two main vegetable growing areas of Yunnan province. [Methods]  During 2008-2015, resistance levels of these two diamondback moth populations to abamection, spinosad and Bacillus thuringiensis(BT) were assessed by the leaf-dipping method in a laboratory. [Results]  In 2008, resistance to abamectin and spinosad were high in both populations. With respect to abamectin, the respective LC_50s for Tonghai and Midu were 34.017 and 25.688 mg/L, and the resistance ratios were 1 700.85 and 1 284.40, respectively. For spinosad, LC_50s were 13.728 and 19.830 mg/L, respectively, and the resistance ratios were 114.40 and 165.25, respectively. Both populations were highly resistant to spinosad. With respect to Bt, the respective LC_50s for each population were 0.530 and 0.538 mg/L, and the resistance ratios were 2.04 and 2.07, respectively, which are relatively low. By 2015, the respective resistance ratios of the two diamondback moth populations to abamectin had dropped to 455.70 and 255.05. Although this decrease was statistically significant, resistance remained high. There was no significant drop in spinosad resistance in either population in 2015, resistance ratios remained a moderate 35.56 and 75.28, respectively, in that year. There was, however, a significant difference in resistance between years; the LC₅₀ increasing from 0.885 to 19.830 mg/L. Both populations remained sensitive to Bt; with resistance ratios in 2015 of 5.41 and 1.73, respectively. [Conclusion]  The resistance of the Tonghai and Midu populations of P. xylostella to the three biopesticides were similar from 2008 to 2015. Although resistance to abamectin and spinosad declined over time, it remained relatively high. Both populations currently only display low resistance to Bt and consequently we recommend using Bt in rotation with other insecticides to improve control of the diamondback moth in Yunnan.