The detoxification enzymes activities were investigated to Tetranychus urticae Koch using five acaricide-resistant strains. Activities of detoxification enzymes which are glutathione S-transferase (GST), general esterases (α-naphthyl acetate and β-naphthyl acetate), and cytochrome C oxidase were determined to each resistant strain mite. Acequinocyl-resistant strain and bifenazate-resistant strain of T. urticae were showed 2.1 folds and 1.6 folds higher relative activity (RA) level of GST than susceptible strain. Other three resistant strain mites were not significant different to susceptible strain mite. General esterases and cytochrome C oxidase were not significant to all the strain of T. urticae. Acaricidal activities of acequinocylresistant strain and bifenazate-resistant strain of T. urticae showed cross-resistant both acequinocyl and bifenazate. However, other strain mites were showed susceptible acaricidal activities to two acaricides.
In this result suggests that resistance of two acaricides (acequinocyl and bifenazate) might be influenced by glutathione S-tansferase activity.

• Seon-Woo Lee(Department of Plant medicine, Chungbuk National University)
• Seung-Hwan Yun(Department of Plant medicine, Chungbuk National University)
• Hyun-Na Koo(Department of Plant medicine, Chungbuk National University)
• Gil-Hah Kim(Department of Plant medicine, Chungbuk National University)