Nanoclay-Mediated RNA Interference Targeting Insecticide Receptors Enhances Whitefly Mortality and Reduces Fecundity

The whitefly Bemisia tabaci is an invasive, polyphagous pest that transmits pathogenic plant viruses in several important crops worldwide. Whitefly management is challenging because of their rapid reproduction, polyphagy and development of resistance against conventional insecticides. RNA interference (RNAi) is a next-generation biopesticide technology with high species-specificity and environmentally friendly. Clay nanosheets are used in this study as a carrier for dsRNAs delivery targeting two B. tabaci insecticide receptors, ryanodine receptor (BtRyR) and nicotinic acetylcholine receptor subunit β1 (BtnAChR-β1), via foliar spray and root dip method. Clay nanoparticles are synthesised by the hydrothermal method and characterised to confirm an average diameter of 42 nm. Synthesised nanoclay loaded with dsRNA, and the complete loading ratio achieved was 1:10 (dsRNA: Nanoclay). Three different concentrations of dsRNA-nanoclay complex were taken (20 µg/mL, 40 µg/mL, and 60 µg/mL). A Real-Time qPCR analysis indicated a significant reduction in the expression of both targeted genes (~ 30-70%). Silencing of both target genes led to decreased survival (60-100% for different treatments), reduced egg laying (48.19-10.81% as compared to control) and delayed adult emergence (34.88-7.26% as compared to control). Gene silencing using the root dip method shows higher efficiency than the foliar spray method. LC₅₀ for the dsRNA-nanoclay complex of BtRyR and BtnAChR-β1 for the root dip method was 16.08 µg/mL and 14.13 µg/mL, respectively, lower than those of dsRNA alone for both target genes. These findings emphasize the practical applicability of clay nanosheet-based RNAi as an eco-friendly and scalable strategy for effective management of B. tabaci sustainable alternative to chemical insecticides.