Foliar and root absorption of LDH nanosheets loaded with dsRNAs efficiently silenced the expression of whitefly Bemisia tabaci Laccase 1 and Vitellogenin Receptor genes for their effective control.

内容摘要

Whitefly Bemisia tabaci, a most damaging sap-sucking pest, has threatened food and nutrition security globally. Its management is quite challenging due to its short life cycle, rapid reproduction rate, and ability to evolve resistance to synthetic pesticides. The purpose of this study is to evaluate the efficacy of exogenously supplied, non-transgenic RNAi-based biopesticides by synthesizing double-stranded RNAs (dsRNAs) targeting two essential genes Laccase 1 and Vitellogenin receptor, in whitefly. dsRNA of B. tabaci Laccase 1 (BtLac 1) and Vitellogenin Receptor (BtVgR) genes are synthesized by in-vitro transcription and conjugated with Layered Double Hydroxide (LDH) nanosheets delivered via plant foliar spray or root absorption to silence the B. tabaci complementary target genes. Downregulation of genes was confirmed by the quantitative real-time PCR (RT-qPCR) and confocal microscopy. Silencing of the target genes BtLac1 or BtVgR has caused significant mortality, reduced egg laying, and reduced adult emergence. Uptake of blue dye by whitefly nymphs was confirmed by visual observation under a stereomicroscope, where the presence of dye in their bodies indicated the movement of dsRNA/dsRNA-LDH from plants and subsequent gene silencing. BtLac1 dsRNA-LDH more efficiently induced maximum whitefly mortality (92%), reductions in egg-laying (66%) and adult emergence (79%), than BtVgR dsRNA-LDH; however, the latter triggered the greatest decrease in gene expression (79.3%). Root absorption with dsRNA-LDH was more efficient than foliar spray. The nanosheets-loaded dsRNA remained stable for more than seven days post-treatment. Furthermore, this technique is safer and more environmentally sustainable than traditional chemical control methods, as it enables gene-specific silencing across the whitefly's life cycle stages.