Biogenic synthesis of silver nanoparticles using Bacillus thuringiensis and its secondary metabolites; New generation bioinsecticides, current trends and future perspectives

Abstract

The growing demand for sustainable pest control solutions has propelled the development of biologically derived nanobiopesticides, with Bacillus thuringiensis (Bt)-mediated silver nanoparticles (AgNPs) emerging as a promising innovation. Silver NPs are silver oxide dominated. This review addresses the green synthesis of Ag₂ONPs utilizing Bt and its chitinase enzyme. Here we are emphasizing the unique physicochemical and bioactive characteristics that position these nanoparticles at the forefront of next-generation biopesticides. Bt-Ag₂ONPs combine the entomopathogenic potency of Bt with the oxidative and antimicrobial properties of silver, yielding dual-action nanoconjugates that demonstrate enhanced insecticidal activity, reduced pupal emergence, and broad-spectrum efficacy against agricultural pest insects. Bt-Ag₂ONPs demonstrated significantly higher insecticidal efficacy against Tribolium castaneum compared to Bt alone or commercial Ag₂ONPs. These nanoparticles also markedly suppressed pupal emergence, underscoring their potent developmental inhibition effects. Furthermore, the biosynthesis process is environmentally benign, cost-effective, and highly tunable, allowing for control over nanoparticle size, dispersity, and stability. There are several limitations about their ecotoxicology and regulations that are discussed in this review. The review also addresses current trends in formulation science, including smart delivery systems and precision-targeted applications as well as future research directions in synthetic biology and ecotoxicological assessment. Bt-derived Ag₂ONPs represent a powerful, multifaceted tool for integrated pest management strategies, offering a compelling alternative to conventional chemical pesticides and laying the groundwork for more resilient and sustainable agroecosystems.