Transcriptomic resources and functional validation of RNAi in the cabbage seedpod weevil, Ceutorhynchus obstrictus

Area of Science:

• Entomology
• Molecular Biology
• Pest Management

Background:

• Cabbage seedpod weevil (CSW) is a significant pest of oilseed rape, managed primarily with broad-spectrum insecticides.
• Insecticide resistance and regulatory actions necessitate sustainable, selective pest control alternatives.
• RNA interference (RNAi) presents a promising strategy, but requires molecular resources for non-model pests like CSW.

Purpose of the Study:

• To develop molecular resources for CSW by constructing its transcriptome.
• To identify and characterize core RNAi pathway genes and potential RNAi target genes in CSW.
• To evaluate the efficacy of RNAi in reducing target gene expression and inducing mortality in CSW.

Main Methods:

• Transcriptome sequencing of CSW to identify genes.
• Characterization of RNAi pathway genes and candidate target genes (αCOP, ncm, Rop, RpII140, dre4, Spt5, Spt6).
• Delivery of double-stranded RNA (dsRNA) targeting candidate genes via microinjection to assess transcript reduction and mortality.

Main Results:

• The CSW transcriptome provided a resource for identifying RNAi pathway and target genes.
• Microinjection of dsRNA targeting six candidate genes resulted in significant transcript reduction (>70%) in adult CSW.
• Silencing of αCOP and Rop led to the highest mortality rates (76.7% and 77.7% respectively) at 15 days post-injection.

Conclusions:

• This study provides the first transcriptomic resource for CSW and demonstrates the potential of RNAi technology for pest control.
• The identified RNAi machinery and successful gene silencing leading to mortality support RNAi as a viable strategy for CSW management.
• αCOP and Rop are identified as promising targets for developing future RNAi-based control strategies against the cabbage seedpod weevil.