Adoption of Bacillus thuringiensis-based biopesticides in agricultural systems and new approaches to improve their use in Brazil

Biopesticides based on the entomopathogenic bacteria Bacillus thuringiensis (Bt) are used worldwide on broad-extensions of different crops and vegetables, mainly against lepidopteran and coleopteran pests. The first attempts to use this microbial control agent as biopesticide date from 1938, but it was until 1970s that some quality constraints on the formulations were solved, and right now, multiple formulations are available in the market and are used in the field. The high selectivity of Bt pesticidal proteins, without harming natural enemies and non-target organisms, is the main factor involved in their reduced environmental risk, in contrast with the broad-spectrum chemical pesticides. Moreover, the high efficacy of Bt biopesticides has already played a significant role in suppressing some pests' outbreaks. Nevertheless, despite the improvements of Bt formulations over the past 50 years, abiotic factors such as temperature, ultraviolet radiation, rainfall, and other factors such as farmer practices are still considered the main obstacles to the broader adoption of Bt biopesticides. Here, we discuss the challenges of Bt biopesticides and the perspectives to improve their adoption, including tank mixtures, technology application, formulations, and insect resistance.