Transcriptome Analysis of the Carmine Spider Mite, Tetranychus cinnabarinus (Boisduval, 1867) (Acari: Tetranychidae), and Its Response to β-Sitosterol.

Tetranychus cinnabarinus (Acari: Tetranychidae) is a worldwide polyphagous agricultural pest that has the title of resistance champion among arthropods. We reported previously the identification of the acaricidal compound β-sitosterol from Mentha piperita and Inula japonica. However, the acaricidal mechanism of β-sitosterol is unclear. Due to the limited genetic research carried out, we de novo assembled the transcriptome of T. cinnabarinus using Illumina sequencing and conducted a differential expression analysis of control and β-sitosterol-treated mites. In total, we obtained >5.4 G high-quality bases for each sample with unprecedented sequencing depth and assembled them into 22,941 unigenes. We identified 617 xenobiotic metabolism-related genes involved in detoxification, binding, and transporting of xenobiotics. A highly expanded xenobiotic metabolic system was found in mites. T. cinnabarinus detoxification genes-including carboxyl/cholinesterase and ABC transporter class C-were upregulated after β-sitosterol treatment. Defense-related proteins, such as Toll-like receptor, legumain, and serine proteases, were also activated. Furthermore, other important genes-such as the chloride channel protein, cytochrome b, carboxypeptidase, peritrophic membrane chitin binding protein, and calphostin-may also play important roles in mites' response to β-sitosterol. Our results demonstrate that high-throughput-omics tool facilitates identification of xenobiotic metabolism-related genes and illustration of the acaricidal mechanisms of β-sitosterol.