Hidden pesticidal diversity within the Bacillus cereus group: expanding the concept beyond Bacillus thuringiensis

For over a century, Bacillus thuringiensis has been regarded as the primary microbial source of pesticidal proteins used in agriculture and vector control. Its defining phenotype, the production of parasporal crystals composed mainly of Cry and Cyt proteins, has shaped both scientific understanding and regulatory frameworks. However, advances in whole genome sequencing reveal that pesticidal traits are not restricted to a single species but are distributed across members of the Bacillus cereus group. This distribution is largely driven by the mobility of toxin-associated genetic elements across closely related genomic backgrounds. Here, we propose that this observation reflects a broader, dynamic, and largely unexplored functional diversity. Using the emerging case of Bacillus toyonensis biovar Thuringiensis, we argue that the current species centered paradigm may be limiting the discovery of novel pesticidal diversity and propose a shift toward a function centered framework in microbial biocontrol. We suggest that embracing this perspective will not only refine our understanding of microbial evolution but also open new avenues for the development of sustainable, next generation biopesticides. Furthermore, it may facilitate the systematic discovery of previously overlooked pesticidal diversity hidden within historical microbial collections.