Silencing Chitinase Genes Increases Susceptibility of (Boisduval) to Scopoletin.

The carmine spider mite is a major pest of crop and vegetable plants worldwide. Previous studies have shown that scopoletin is a promising acaricidal compound against However, the acaricidal mechanism of scopoletin remains unclear. In the present study, 12 full-length cDNAs of chitinase (CHIT) genes from (designated ) were cloned and characterized. Although were expressed throughout all life stages, their expression levels were significantly upregulated during the larval and nymphal stages. were downregulated 24 h after treatment with scopoletin and upregulated 24 h after treatment with diflubenzuron (DFB, a chitin synthesis inhibitor). Feeding double-stranded RNA effectively silenced transcription in , thus increasing its susceptibility to scopoletin but reducing that to DFB. Meanwhile, silencing in larvae and adult resulted in an extremely low molting rate (7.3%) and high mortality rate (53.3%), respectively, compared with those in the control group. CHIT genes are closely related to arthropod survival, molting, and development in , suggesting that acaricidal mechanisms of scopoletin and DFB may occur by inhibition and activation of CHIT gene expression, respectively. constitutes a possible target of scopoletin and DFB in .