LAUSR

BACKGROUND The two-spotted spider mite Tetranychus urticae is a polyphagous and cosmopolitan pest that has developed high resistance to abamectin, making it difficult to control. Although "target resistance" related to GluCl mutations was found in T. urticae field populations in China, other resistance mechanisms appear to be involved. Here, we conducted genome-wide transcriptome profiling using RNA-seq of two abamectin-resistant populations (NB-ZJ and SY-BJ) and one susceptible strain (Lab-SS) to identify differentially expressed genes that might contribute to the resistance of T. urticae to abamectin in China. RESULTS Our experiments showed that abamectin resistance was synergized by PBO and TPP, with synergistic ratios (SR) of 2.95-fold and 2.21-fold for PBO and 3.55-fold and 2.84-fold for TPP in NB-ZJ and SY-BJ populations, respectively. Transcriptome data and qRT-PCR revealed that 7 detoxification enzyme genes were overexpressed in the two resistant populations. Furthermore, functional analysis by RNAi indicated that the mortality caused by abamectin was significantly increased by the separate silencing of the P450 genes CYP389C10, CYP392D8, CYP392A11, and CYP392A12. CONCLUSION qRT-PCR expression and RNAi data suggested that the overexpression of P450 genes CYP389C10, CYP392D8, CYP392A11, and CYP392A12 may be involved in the abamectin-resistance of field populations of T. urticae in China. This knowledge would facilitate the elucidation of resistance mechanisms and the development of resistance management of T. urticae field populations.