截形叶螨抗哒螨灵品系和敏感品系体内解毒酶活性的变化

【目的】通过对截形叶螨 Tetranychus truncatus Ehara抗哒螨灵品系体内解毒酶活性分析和增效剂与哒螨灵混用的增效作用测定，明确截形叶螨对哒螨灵的抗性动态及抗性机理，获得抗性治理的途径。【方法】采用室内生测法培育截形叶螨抗哒螨灵品系，微量滴度酶标板测定抗性和敏感品系体内解毒酶比活性、米氏常数（K_m）及最大反应速度（V_max），再用增效醚（PBO）、顺丁烯二酸二乙酯（DEM）和磷酸三甲苯酯（TPP）进行增效作用测定。【结果】室内筛选的截形叶螨对哒螨灵产生了抗性，筛选至49代，抗性倍数达到955.25；PBO，TPP和DEM对哒螨灵药剂有不同程度的增效作用，相对增效系数分别为95.97%, 85.14%和97.37%；抗哒螨灵品系体内的羧酸酯酶（CarE）、谷胱甘肽转移酶（GSTs）、多功能氧化酶（MFO）活性较敏感品系显著性提高（P＜0.05），酸性磷酸酯酶（ACP）和碱性磷酸酯酶（ALP）的活性与敏感品系差异不大(P>0.05)；抗性品系中的CarE，GSTs和MFO 3种解毒酶的米氏常数（K_m）下降，最大反应速度（V_max）高于敏感品系。【结论】截形叶螨对哒螨灵产生抗性可能与其体内CarE，GSTs和MFO 3种解毒酶与底物的亲和力提高和代谢能力增强有关；3种增效剂(PBO， TPP和 DEM)与哒螨灵混用能提高对截形叶螨的毒杀效果。

Change of detoxification enzyme activities in the pyridaben-resistant and susceptible strains of Tetranychus truncatus (Acarina: Tetranychidae)

【Aim】 To clarify the resistance mechanisms of Tetranychus truncatus Ehara to pyridaben by detecting the change of detoxification enzyme activities and the synergism of synergists to pyridaben. 【Methods】 The experiment was carried out in laboratory by biological assay. The specific activity, the Michaelis constant (K_m) and the maximum reaction velocity (V_max) of several detoxification enzymes in pyridaben resistant strain (Py-R) and susceptible strain (SS) were detected by microplate reader. Then the synergistic effects of piperonyl butoxide (PBO), diethyl maleate (DEM) and icresyl phosphate (TPP) to pyridaben were detected in Py-R and SS.【Results】 The resistance of Py-R at the 49th generation selected with pyridaben increased to 955.25-fold as high as that of SS. The piperonyl butoxide(PBO), triphenyl phosphate (TPP) and diethylmaleate (DEM) enhanced the toxicity of pyridaben, and the relative synergistic coefficients of 3 synergists to pyridaben were 95.97%, 85.14% and 97.37%, respectively. The activities of carboxylesterases (CarE), glutathione-S transferase (GSTs) and mixed function oxidase (MFO) in Py-R significantly increased compared with those in SS (P<0.05), while the activities of acid phosphatase (ACP) and alkaline phosphatase (ALP) had no significant difference between Py-R and SS (P>0.05). The Km values of CarE, GSTs and MFO in Py-R were lower than those in SS, while their V_max values in Py-R were higher than those in SS. 【Conclusion】 The increased activity of CarE, GSTs and MFO, and higher affinity with substrate might be the main resistance mechanisms to Py-R of T. truncatus. When 3 synergists (PBO, TPP and DEM) and pyridaben are mixed, a higher level of virulence to T. truncatus would be exhibited.