Application of a dual-loop double-stranded RNA to control small brown planthopper.

Abstract

RNA interference, induced by double-stranded RNA (dsRNA), has emerged as a biopesticide for pest control. However, the stability of dsRNA remains a challenge in topical delivery, preventing widespread agricultural application. Here, we tested a dsRNA variant, called loop-ended dsRNA or LedRNA, for controlling a notorious vector insect, the small brown planthopper (SBPH). LedRNA is characterized by having a loop at both ends of the dsRNA stem, resembling a close-circled RNA. Three SBPH target genes, including Flotillin2, which is vital for viral transmission, and trehalose-6-phosphate synthase (TPS) and malate dehydrogenases (MDH), which are essential for insect survival, were tested for gene silencing efficiencies through microinjection, soaking, or oral delivery of the conventional dsRNA, hairpin dsRNA, and LedRNA. All 3 molecules induced effective gene silencing using microinjection, but did not suppress target gene expression through soaking. Notably, LedRNA demonstrated superior efficacy in inducing gene silencing in SBPH through oral feeding compared to the other 2 molecules. Silencing efficiencies ranged from 26% to 39% for Flotillin2, 39% to 51% for TPS, and 45% to 64% for MDH. When SBPH were fed Escherichia coli-synthesized LedRNA targeting these 3 genes, silencing efficiencies ultimately reached 28% to 74%, leading to reduced insect survival and decreased viral transmission in host plant rice. This study highlights the potential of LedRNA as a biopesticide for insect pest control.