Molecular target for sprayable double-stranded RNA-based biopesticide against Amphitetranychus viennensis (Acari, Tetranychidae)

Amphitetranychus viennensis, a destructive pest mite of fruit plants in Europe and Asia, poses a serious challenge due to its adaptability and resistance to multiple acaricides. RNA interference (RNAi)-based technologies offer a promising alternative to address this emerging issue. In this study, we screened for candidate genes that can be targeted for spray-induced gene silencing (SIGS). Suppression of AvSrp54k, AveIF4A-1, AvHel31B, AvCOPB2 and AvProsbeta5 led to a significantly higher mortality and caused minor damages to leaf discs in comparison to the controls. Among them, AvCOPB2 and AvProsbeta5 were the best candidates with the highest mortality (>95 %) and minimal leaf damages (<13 %). Given that LdProsbeta5 is the active ingredient of the first sprayable dsRNA-based biopesticide, Ledprona, against the Colorado Potato Beetle, Leptinotarsa decemlineata, we examined the suitability of AvProsbeta5 in managing A. viennensis. In comparison to the control, A. viennensis population was suppressed by >95 % at day-17, and the plant defoliation rate decreased to 0 at day-24. Our combined results not only provide two viable molecular targets for sprayable dsRNA-based biopesticides, but also confirm the practical implications of SIGS in managing A. viennensis, one of the most destructive arthropod pests in orchards and ornamental plants.