Effects of Orally Delivered Double-Stranded RNA of Trehalose-6-Phosphate Synthase on the Population of Frankliniella occidentalis.

The invasive pest Frankliniella occidentalis (western flower thrip, WFT) severely impacts agricultural production. RNA interference (RNAi) has emerged as a viable alternative to chemical control methods. Trehalose-6-phosphate synthase (TPS) is an important enzyme for the synthesis of trehalose in insects. The TPS gene is a potential target for RNAi-based pest control; however, its efficacy against WFTs remains unclear. Feeding with the synthesized dsFoTPS to WFT significantly increased the mortalities of first- and second-instar nymphs and adults and significantly decreased the number of eggs laid by adults within 72 h; the expression of FoTPS was significantly down-regulated in 24, 48, and 72 h. Ingestion of WFTs on Escherichia coli expressing dsFoTPS led to a marked increase in the total pre-reproductive period; reductions in survival rate, adult longevity, oviposition days, fecundity, peak reproduction value, the intrinsic rate of increase, the finite rate of increase, and the net reproductive rate; and an extension of the mean generation time. TPS gene expression was significantly down-regulated on days 7 and 28. A population simulation of WFTs fed with E. coli expressing dsFoTPS indicated that the population suppression was reduced to 1/34 of the control in 100 d. Oral delivery of E. coli expressing dsFoTPS effectively inhibited the survival, fecundity, and population growth of WFTs, offering a novel approach and rationale for the prevention and control of WFTs.