Discovery and Characterization of Chitin Synthase Inhibitors with Novel Mechanism for Control of <i>Tetranychus urticae</i>

<i>Tetranychus urticae</i>, a highly destructive global pest, infests a wide range of plant species, including crucial food crops and ornamental plants. Effective control methods for this pest remain limited. Chitin synthase (CHS) is a key enzyme in the biosynthesis of chitin, which is essential for the growth and development of arthropods. However, the lack of detailed research on arthropod CHS proteins has hindered the development of targeted pesticides. In this study, we successfully expressed and purified the full-length <i>Tu</i>CHS protein, which exhibited significant enzymatic activity <i>in vitro</i>. Utilizing this protein, we developed a reliable screening method to identify inhibitors targeting <i>Tu</i>CHS. Two inhibitors, ZHZ-ZI-11 and SUY-SC-15, were identified. These compounds interfere with chitin translocation within the cell rather than inhibiting CHS enzyme activity. Both inhibitors demonstrated significant acaricidal efficacy, with improved performance when formulated as nanoemulsions. This study presents the first use of arthropod CHS protein for screening potential insecticides targeting chitin biosynthesis during mite development. Our findings provide a solid foundation for the development of novel, environmentally friendly pesticides aimed at CHS.