Tetranychus urticae is extremely hard to control by conventional acaricides due to its rapid development of resistance to nearly all arrays of acaricide. As an alternative control measure of acaricide-resistant mites, RNA interference (RNAi)-based method has recently been suggested. A double-stranded RNA (dsRNA) delivery method using multi-unit chambers was established and employed to screen the RNAi toxicity of 42 T. urticae genes. Among them, the dsRNA treatment of coatomer I (COPI) genes, such as coatomer subunit epsilon (COPE) and beta 2 (COPB2), resulted in high mortality [median lethal time (LT50) = 89.7 and 120.3 h, respectively]. The transcript level of the COPE gene was significantly (F3,9 = 16.2, P = 0.001) reduced up to 24% following dsRNA treatment, suggesting that the toxicity was likely mediated by the RNAi of the target gene. To identify the deferentially expressed gene upon dsRNA ingestion, RNA-seq was employed to compare the transcriptional profiles between mites fed dsEGFP and dsCOPB2. Approximately 928 of genes were up- or down-regulated significantly (P < 0.05) compared to control and 182 genes were commonly responded to the treatment of both dsRNAs. Those dsRNA-responsible genes were mainly categorized into metabolic enzymes, transporters and secretory proteins. Further study would be necessary to elucidate the roles of dsRNA-responsible genes in mite’s dsRNA uptake and defense.

• Deok Ho Kwon(Research Institute of Agriculture and Life Sciences, Seoul National University)
• Ji Hyun Park(Department of Agricultural Biotechnology, Seoul National University)
• Patil Anandrao Ashok(Department of Agricultural Biotechnology, Seoul National University)
• Unggyu Lee(Department of Agricultural Biotechnology, Seoul National University)
• Si Hyeock Lee(Research Institute of Agriculture and Life Sciences, Seoul National University, Department of Agricultural Biotechnology, Seoul National University)