Potential role of the <i>TuCCE50</i> gene in abamectin resistance in field populations of <i>Tetranychus urticae</i> Koch

The two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) has developed resistance to various pesticides at different levels. While target-site resistance mechanisms are recognized, metabolic resistance plays a crucial role in this development. In this study, a carboxyl/choline esterase gene, TuCCE50, was found to be significantly overexpressed in all tested field populations of T. urticae that exhibited resistance to abamectin and profenofos. Notably, exposure to abamectin significantly upregulated the expression of the TuCCE50 gene, an effect that was also observed with profenofos but only at 1 of the 2 tested concentrations. RNA interference-mediated knockdown of the TuCCE50 gene significantly increased the susceptibility of adult female T. urticae to abamectin, but not to profenofos. Homology modeling and molecular docking analyses further revealed that the TuCCE50 protein can bind to abamectin via hydrogen bonds formed with 4 specific residues. The findings indicate that the overexpression of TuCCE50 gene likely plays an important role in the development of resistance to abamectin in T. urticae field populations. This study sheds light on the mechanisms driving the evolution of pesticide resistance, enhancing our understanding of this critical phenomenon.