Environmental stability and persistence of Bacillus thuringiensis-based biopesticides: A comprehensive review of mechanisms and advancements.

Bacillus thuringiensis (Bt) is currently the most successful microbial biopesticide globally. Despite this, its potential to mitigate the devastating effects of chemical pesticides and its widespread adoption in large-scale field applications have not yet been fully realized due to its sensitivity to various environmental stressors. Among these stressors are ultraviolet radiation, temperature, precipitation, pH fluctuations, soil properties, and leaf surface morphology. Previous studies have assessed the individual impact of these factors on the degradation of Bt spores and Cry proteins. This review provides critical insight into the major environmental stressors that influence the persistence, stability, and efficacy of Bt-based biopesticides in field applications. Particularly, we address the mechanisms by which these stressors degrade Bt biopesticides and contribute to their poor success in field applications. Moreover, various formulation strategies, including microencapsulation, nanotechnology and Pickering emulsions, drying, hydrogels, and cell-encapsulation, that have been adopted over the past decades to overcome the environmental challenges associated with Bt-based pesticides are discussed. The strengths and limitations of these techniques in improving the stability and persistence of Bt biopesticides are evaluated. This study serves as a guide for researchers, farmers, engineers, and Bt biopesticide manufacturers regarding the use of formulation strategies to improve the environmental shelf-life, stability, and efficacy of Bt products.