Toxicological and Functional Assessment of Minicell-Encapsulated dsRNA on Biocontrol Agents in Agriculture

Double-stranded RNA (dsRNA)-based biopesticides represent promising tools for target-oriented pest and pathogen control. However, their compatibility with beneficial organisms used in biological control programs is not clear. In this study, the potential interactions between two dsRNA formulations─naked and minicell-encapsulated (ME-dsRNA)─and different commercialized bacterial, fungal, and insect biocontrol agents (BCAs) were examined. There was no toxicity of either of the two dsRNA formulations toward Bacillus amyloliquefaciens, Trichoderma harzianum, or Ulocladium oudemansii, based on growth assays. ME-dsRNA significantly enhanced fungal BCA growth, likely due to improved uptake or protection. Coapplication trials on strawberry fruit and foliage showed that coapplication of dsRNA and BCAs was efficacious with no evidence of synergistic or antagonistic effects. Insect bioassays demonstrated that dsRNA sprays had no adverse effects on predatory mite populations (Amblyseius swirskii and Phytoseiulus persimilis). Additionally, in silico off-target analysis detected minimal potential matches in T. harzianum and Tetranychus urticae, none of which corresponded to in vivo toxicity. Markedly, greenhouse and in vitro assays confirmed that neither dsRNA formulation interfered with the biocontrol efficacy of BCAs on Botrytis cinerea in strawberry. Overall, this study provides strong evidence that dsRNA-based products, including ME-dsRNA, are compatible with key BCAs and pose minimal ecological risk.