Target gene selection for RNAi‐based biopesticides against the hawthorn spider mite, Amphitetranychus viennensis (Acari: Tetranychidae)

Abstract

BACKGROUND Recently, RNA interference (RNAi)‐based biopesticide, a species‐specific pest control alternative, has been deregulated and commercialized in the US and Canada. The hawthorn spider mite, Amphitetranychus viennensis Zacher, is a major pest for rosaceous plants, which has been controlled primarily by synthetic pesticides. To address the emerging resistance issues in A. viennensis, we initiated a project to develop RNAi‐based biopesticides. RESULTS In this study, we (i) developed a dietary RNAi system for A. viennensis using leaf disc, (ii) assessed the suitability of multiple control genes to distinguish sequence‐specific silencing from non‐specific effects within this RNAi system, and (iii) screened for the target gene candidates. As a result, β‐Glucuronidase (GUS), an enzyme derived from E. coli and a broadly used reporter for plants is the appropriate control for A. viennensis RNAi, while green fluorescent protein (GFP), is not suitable due to its significantly higher mortality than the other controls. For target gene screening, suppression was confirmed for all the candidates, including two housekeeping genes (Vacuolar‐type H + ‐ATPase subunit A (V‐ATPase A) and Glyceraldehyde 3‐phosphate dehydrogenase, (GAPDH)), and three genes associated with development (ATP‐dependent RNA Helicase DDX3Y (Belle), CREB‐binding protein (CBP), and Farnesoic acid O‐methyltransferase (FaMet)). Knocking down of V‐ATPase A resulted in the highest mortality (~ 90%) and reduced fecundity (over 90%) than other candidates. As for the genes associated with development, suppression of Belle and CBP, led to approximately 65% mortality, as well as 86% and 40% reduction in fecundity, respectively. Silencing of FaMet, however, had negligible biological impacts on A. viennensis. CONCLUSION The combined efforts not only establish an effective dsRNA delivery method, but also provide potential target genes for RNAi‐based biopesticides against A. viennensis, a devastating invasive pest for fruit trees and woody ornamental plants throughout Asia and Europe. © 2023 Society of Chemical Industry.

Differential Antioxidant Enzyme Gene Expression and Functional Analysis of Pyridaben-Susceptible and -Resistant Strains of Tetranychus truncatus (Acari: Tetranychidae) under High Temperature Stress

“…According to the research method by Yang et al [ 34 ], the specific operation of feeding the gene of T. truncatus was as follows: bean leaves were cut into squares of 1.5 × 1.5 cm in size, dried in an oven at 60 °C for 3 min, and treated with 50 μL dsRNA solution at a concentration of 1000 ng/μL for 1–2 h; then, the dsRNA solution was fully absorbed and the leaves were placed in a Petri dish (9 cm in diameter). Fifty female adult mites that were starved for 24 h at room temperature were selected, and the leaves were treated with water as the blank control and GFP as the negative control.…”

RNAi silencing CHS1 gene shortens the mortality time of Plutella xylostella feeding Bt‐transgenic Brassica napus

“…11 RNA interference (RNAi) is considered to have considerable potential for insect pest control as an alternative or supplement to Bt-based methods. [12][13][14] With RNAi, small double-stranded RNA (dsRNA) causes sequence-specific suppression of target gene expression and ultimately leads to mortality or severe sublethal effects. 15,16 RNAi-based silencing of vital insect genes has been used against the resistance evolution of target insects to Bttransgenic plants.…”