Bacterial insecticides beyond Bacillus thuringiensis

Abstract Bacterial insecticides have emerged as a biotechnological strategy for controlling insect pests in crops, primarily due to the ineffectiveness of synthetic pesticides, which have led to resistance in insect populations due to their overuse. For many years, Bacillus thuringiensis has been recognized as the most promising microorganism for this purpose, while other entomopathogenic bacteria, which have demonstrated efficacy against various insect orders, have been largely overlooked. These entomopathogenic bacteria employ diverse mechanisms to control insect pests, including damage via contact or ingestion, disruption of intestinal cell integrity, interference with the insect's central nervous system, and alterations to reproductive processes. Among the insecticidal compounds produced by these bacteria are Cry homologous toxins, non-homologous toxins, biosurfactant-type compounds, macrocyclic lactones, lipopeptides, chitinases, and other metabolites that remain underexplored. This paper provides a comprehensive overview of the current state of lesser-known entomopathogenic bacteria utilized in the development of these biopesticides. It discusses the advantages and disadvantages of these biotechnological products, the mechanisms of action of entomopathogenic bacteria, genetic engineering strategies aimed at enhancing these biopesticides, and the application of these bacteria in commercial production. Additionally, the paper reviews patents related to this field and examines the role of insecticidal bacteria as inducers of systemic resistance (ISR) in plants, highlighting their potential for the development of commercial bioproducts.