A systemically applied nanoparticle-based dsRNA biopesticide reduces Tuta absoluta survival

RNA interference (RNAi) is an endogenous eukaryote viral defence mechanism representing a unique form of post-transcriptional gene silencing that can be induced via the exongenous application of dsRNA. Due to its high specificity, dsRNA-based biopesticides are being developed to control pest insects. Whilst many lepidopteran species are recalcitrant to RNAi, Tuta absoluta, a polyphagous insect responsible for extensive crop damage, is sensitive. Ryanodine receptors (RyRs) are intracellular calcium channels regulating Ca²⁺ release in the post-synaptic axon. Diamides function agonistically against lepidopteran RyR, resulting in uncontrolled Ca²⁺ release, feeding cessation and death. Resistance to Diamides has emerged in T. absoluta, derived from RyR point mutations. This study uses RNAi to target RyR transcripts of T. absoluta. Data presented here demonstrate the systemic use of exogenous T. absoluta RyR specific (TaRy) dsRNA protected in a chitosan based nanoformulation, in hydroponically grown tomato plants (Solanum lycopersicum). dsRNA treatments resulted in significantly downregulate expression of the target gene, resulting in significant insect mortality and reduced leaf damage. TaRy dsRNA was more stable in tomato leaves, T. absoluta gut extract and haemolymph when incorporated in a chitosan nanoformulation. Bioinformatic and in vitro biosafety studies demonstrate the compatibility of TaRy dsRNA with non-target arthropods. This work identifies TaRy dsRNA-CS-TPP molecules as effective and environmentally safe for RNAi-control of T. absoluta.