【目的】 测定截形叶螨Tetranychus truncatus敏感品系（SS）、抗哒螨灵品系（Py-R）体内的自由基和保护酶的变化，探究截形叶螨在药剂和高温的双重胁迫下的应激反应，为叶螨的综合治理提供一定的理论基础。【方法】 经哒螨灵和38 ℃高温处理后，测定截形叶螨不同品系体内的可溶性蛋白含量、超氧自由基（∙O₂^－）和超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性，并分析自由基和3种保护酶的变化与药剂和高温双重胁迫的相关性。【结果】 截形叶螨敏感品系和抗性品系经哒螨灵和高温处理后体内∙O₂^－含量分别是对照的5.519 2倍和1.346 2倍，SOD活性分别是对照的5.344 7倍和7.105 2倍，CAT和POD活性也均高于对照。【结论】 截形叶螨体内的∙O₂^－、SOD、CAT和POD与哒螨灵药物和高温胁迫有关，Py-R在长期哒螨灵胁迫作用下对保护酶活性的诱导能力加强。

[Objectives]  To investigate changes in free radical and protective enzyme levels induced by exposure to pyridaben and a high temperature, in a sensitive (SS) and pyryl-R resistant (Py-R) strain of Tetranychus truncatus. [Methods]  Soluble protein content and activity of the superoxide radical (∙O₂^－), superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), in the SS and Py-R strains were determined after treatment with pyridaben and exposure to 38 ℃. The interaction between free radicals and three protective enzymes was also analyzed. [Results]  The ∙O₂^－ content of the SS and Py-R strains were 5.5192 and 1.3462 times higher than that of the control group after exposure to pyridaben and the high temperature, and SOD activity was 5.344 7 and 7.105 2 times higher. CAT and POD activity were also higher than in the control group. [Conclusion]  ∙O₂^－, SOD, CAT and POD levels in T. truncatus are affected by pyridaben and high temperature stress, and the Py-R strain has higher protective enzyme activity under long-term pyridaben stress.