Encapsulation of the Biocontrol Agent Beauveria bassiana in Cellulose Nanomaterial-Stabilized Pickering Emulsion for Foliar Application

Encapsulation of living cells is a structural enhancement method by providing a viable environment to tolerate various environmental stresses such as ultraviolet (UV) radiation. The shells provided by encapsulation are constructed of additional protective layers to extend the in vitro cell lifespan. Here, we present a cellulose nanomaterial (CNM)-stabilized Pickering emulsion to encapsulate Beauveria bassiana spores. B. bassiana is a widely used biocontrol agent against agricultural insect pests but is unable to survive under sunlight when applied to crop plants in the field. We synthesized Pickering emulsions stabilized by cellulose nanocrystals and cellulose nanofibrils at various ratios and analyzed the phase stability, emulsion size distribution, colloidal stability, and rheological properties. The most stable Pickering emulsion composition was then selected to encapsulate B. bassiana conidia. The encapsulated conidia maintained their viability to germinate and grow and showed excellent insecticidal activity, even after UV radiation exposure. This work demonstrated that CNM-stabilized Pickering emulsions could be utilized to encapsulate microbial cells to maintain cell viability under unfavorable environmental conditions. This finding showed the increased efficacy of B. bassiana for foliar application; this research could lead to significant advances in sustainable agriculture regarding eco-friendly pest control.