Resistance of Tetranychus uraticae Koch to Some Compounds in Cotton Fields and Biochemical Resistance Mechanisms

The field populations of the two-spotted spider mite, Tetranychus uraticae Koch were collected from cotton fields at Sakha Agric. Res. Station Farm Kafr El-Sheikh, Egypt in 2017 season. Five compounds belonged to different groups were assayed by the leaf disc dip technique to determine levels of resistance to these compounds in addition to the activity of some detoxification enzymes. The field populations of T. uraticae showed variation in susceptibility to tested compounds, abamectin was the most toxic one, while chlorpyrifos and deltamethrin were the least toxic against laboratory and field populations. Moreover, the resistance ratios of fenpyroximate exhibited the high resistance level, while abamectin exhibited moderate resistance. Lower resistance levels were observed for Chlorfenapyr, deltamethrin and chlorpyrifos. Based on the susceptibility factor values, the tested compounds showed variation in susceptibility factor values, it’s were exhibited low effective which susceptibility factor values were more than 0.5.  On the other hand, the specific activity of mixed function oxidase and carboxylesterase were higher in field populations than that in laboratory strain. In contrast, there is an insignificant difference in glutathione-s-transferase activity between field and laboratory strain. The obtained results could be used as a basis for future resistance T. uraticae monitoring program in cotton fields