Identification of novel target genes for RNAi mediated management of the pest, Fall Armyworm (Spodoptera frugiperda, J. E. Smith)

Abstract

RNA interference (RNAi) of vital insect genes is a potential tool for targeted pest management. However, the selection of the right target genes and its dsRNA delivery method is also a challenge because the RNAi efficacy is known to vary among insect species. Fall Armyworm (FAW; Spodoptera frugiperda) is a polyphagous generalist insect pest that can feed on more than 100 plant species, with a strong preference for maize. In the present study, we evaluated the RNAi efficiency of three vital genes coding for Coatomer Subunit alpha (COPIα), Coatomer Subunit beta (COPIβ) and Glutathione-S-transferase U1 (GSTU1) as potential targets for managing FAW. Real-time PCR analysis showed that the target genes' expression level reduced to 75–80% in FAW larvae, after their continuous oral delivery through diet for 8 days. It also caused significant mortality in larvae (40–50%) and pupae (40–62%), and resulted in deformed intermediates (28–38%) and adults (25–40%). It also affected reproduction as evidenced by an approximately 50% reduction in oviposition. Moreover, exogenous application of dsRNA in maize leaves resulted in significant feeding deterrence by FAW larvae, which enhanced the frequency of cannibalism. The impact of target genes’ dsRNA on the biology and behaviour of FAW suggests their insecticidal potential. Thus, the current study reveals the novel target genes and their utility in RNA based pesticides for sustainable management of FAW.