Identification of lethal genes for RNAi-mediated control of Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae)

The western flower thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is a globally significant pest causing severe damage to a wide range of crops. Although RNA interference (RNAi) technology enables species-specific pest control through targeted gene silencing, the limited number of validated efficient RNAi target genes has hindered practical application of RNAi for WFT management. This study aims to screen and identify effective RNAi target genes in WFT using an optimized oral delivery system. We selected 15 candidate target genes based on homologous sequences from closely related insect species. DsRNAs targeting these genes were synthesized and fed to WFT nymphs and adults. Mortality and fecundity were monitored at 24, 48, and 72 h post feeding. Feeding on the dsRNAs of six genes (V-type proton ATPase catalytic subunit A, V-type proton ATPase catalytic subunit B, Neuropeptide F receptor, Maltase A1, sorting and assembly machinery component 50 homolog, toll-like receptor 6) significantly increased mortality in WFT nymphs and adults, with a higher lethal effects observed in nymphs. Notably, toll-like receptor 6 knock-down resulted in the highest mortality, and the daily fecundity of adult WFT fed with dsRNA targeting Neuropeptide F receptor for 72 h increased significantly. Expression analysis confirmed significant down-regulation of these 6 target genes by dsRNA. This study identified six high-efficacy target genes for RNAi-based WFT management, establishing a foundation for developing environmentally sustainable RNAi biopesticides.