Improving RNAi in the fall armyworm, Spodoptera frugiperda

Area of Science:

• Agricultural Entomology
• Molecular Entomology
• Pest Management

Background:

• Insecticide resistance necessitates sustainable pest control alternatives.
• RNA interference (RNAi) shows promise but faces challenges in lepidopteran pests, including dsRNA degradation and inefficient delivery.
• Nanoformulations can improve dsRNA delivery, but consistent high mortality is not guaranteed.

Purpose of the Study:

• To evaluate PLL/EGCG/dsRNA nanoformulations for enhanced RNAi efficacy in *S. frugiperda*.
• To validate nanoparticle-mediated RNAi by targeting the inhibitor of apoptosis (IAP) gene.
• To assess the efficacy of targeting additional candidate genes identified from genome-wide screens.

Main Methods:

• Development and application of PLL/EGCG/dsRNA nanoformulations for RNAi delivery.
• Targeting the inhibitor of apoptosis (IAP) gene in *S. frugiperda* larvae.
• Evaluating gene silencing and larval mortality after dsRNA treatment.
• Testing 14 additional candidate genes, including proteasome subunit β-type 4 (BT4) and 60S ribosomal protein L11 (RPL11), using nanoformulations.

Main Results:

• Nanoformulated dsRNA targeting IAP achieved 80% mRNA reduction and 63% larval mortality in *S. frugiperda*.
• This confirms that improved dsRNA delivery significantly enhances RNAi efficacy in lepidopteran pests.
• While other tested genes showed moderate mortality, IAP proved to be the most effective RNAi target among those evaluated.

Conclusions:

• PLL/EGCG/dsRNA nanoformulations significantly improve RNAi efficacy against *S. frugiperda*.
• Targeting the IAP gene is a highly effective strategy for RNAi-based pest control in this species.
• Further research into optimal target gene selection is crucial for maximizing RNAi effectiveness in pest management.