Silencing of Rieske iron–sulfur protein using chemically synthesised siRNA as a potential biopesticide against Plutella xylostella

Abstract

Extensive applications and frequent long-term use of pesticides can affect behavioural mechanisms and physiological and biochemical aspects of insects, leading to resistance. However, insect control strategies involving a different mode of action would be valuable for managing the emergence of insect resistance. In this context, the development of RNA interference technology has brought a turning point in the creation of new biopesticides. Full-length cDNA of Rieske iron-sulfur protein (RISP) was cloned and characterised from Plutella xylostella L. Three siRNAs specific to RISP sequences were designed and chemically synthesised, and fed to P. xylostella larvae by coating cabbage leaves. This resulted in specific gene silencing of RISP, and consequently brought significant mortality of P. xylostella larvae compared with the control treatment. Silencing of RISP leads to significantly lower transcript levels of RISP compared with the control. In addition, the amount of ATP in the surviving larvae was lower than in the control. However, surviving larvae gradually recovered to normal transcript and protein levels. This is the first demonstration of the potential use of chemically synthesised siRNA in the development of new biopesticides as a mitochondrial electron transport inhibitor.