Ecological Safety of RNAi Biofungicides: Assessing the Impact of Spray-Induced Gene Silencing on the Indigenous Phyllosphere Microbiome of Tropical Staples

The recent epidemic of ginger blight disease in Nigeria has resulted in unprecedented yield losses, with economic damages exceeding ₦12 billion in 2023 alone. A complex of soil-borne fungal diseases, mainly Fusarium and Aspergillus species, which have demonstrated a high level of developing resistance to traditional synthetic fungicides, is most likely responsible for this enormous economic loss
. Spray-Induced Gene Silencing (SIGS), a non-transgenic application of RNA interference (RNAi), has emerged as a high-precision, eco-friendly alternative for managing such aggressive pathogens by topically applying double-stranded RNA (dsRNA) to silence essential virulence genes. However, the ecological safety of deploying SIGS in the high-biodiversity, high-stress tropical environments of Sub-Saharan Africa remains poorly understood. This review critically evaluates the potential impact of exogenous dsRNA applications on the indigenous phyllosphere microbiome, the diverse community of epiphytic bacteria and fungi that form a vital biological shield on the leaf surfaces of tropical staples like ginger. We examine the stability of SIGS formulations under tropical stressors, such as extreme UV radiation and humidity, and analyze the bioinformatics-based risks of non-target silencing within the local microbial niche. Furthermore, the role of bio-based nanocarriers, such as chitosan, in modulating these microbial interactions is discussed. By synthesizing current molecular findings with tropical ecological imperatives, this paper provides a framework for the safe integration of RNAi-based biopesticides into Nigerian integrated pest management (IPM) systems, ensuring that innovation does not come at the cost of microbial equilibrium.