| The test sample of Tetranychus cinnabarinus was collected from the field and maintained in the lab to study the resistance to pyridaben miticide. Following the tests of 12 generations, this mite population has gotten a resistance of 6-fold to pyridaben with a relatively slow increase of the resistance level. However, this implies T. cinnabarinus can have a potential resistance to pyridaben in the field application.Based on the method recommended by FAO, the resistance of the mites to pyridaben was evaluated via 12 generations in the lab. condition. The LC50 of T. cinnabarinus population to pyridaben was increased from 3.0409μg/ml at FO generation to 12.9150μg/ml at Fr generation which increased to 4.2 folds. After the incubation of 13 generations of these mite population, a single couple-clone mite was selected to generate young generation for the resistant test to pyridaben, the LC50 of this clone to pyridaben was 2.1445 μg/ml with 1.5 fold sensitivity, which showed a resistant level at 6.2 fold through this resistance screening study. The separate lab cultures for both the resistant and sensitive mite clones indicated that the the life cycle of both resistant and sensitive clones could be shorten at a high temperature conditions and the life cycle of the resistant clone can be shorter than that of the sensitive one. Moreover, the resistant clone can not complete its life cycle under the temperature of 34℃.The biological activities of some enzymes of those resistant and sensitive mite clones were tested, including CarE, GSTs, SOD, CAT, POD. The results indicated the activity of GSTs was similar in both resistant and sensitive clones, but CAT and CarE were higher in the resistant clone than that in the sensitive clone, while SOD and POD were higher in the sensitive clone than that in the resistant clone, which indicated the variation of these enzyme activities may be associated with the resistant mechanism of T. cinnabarinus to pyridaben.
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