ABSTRACT
The indiscriminate use of chemical insecticides has been causing serious problems related to environmental damage and problems to human health. In addition to these damages, chemical insecticides have been decreasing their efficiency and causing the emergence of resistant insect populations. Because of these problems, it is of utmost importance to use alternative control measures that provide less environmental impact. This has been encouraging the use of biological control with entomopathogenic microorganisms. Among the most used entomopathogenic microorganisms is the bacterium Bacillus thuringiensis (Bt), characterized by the ability to form protein crystals during the stationary or sporulation phase. These crystals are degraded by proteolytic enzymes that release proteins called delta-endotoxins, which are restricted to the digestive tract of insects. Some biopesticides based on Bt have been marketed for having high specificity, lower environmental risk and human health, and lower frequency of resistance in target insects (Maagd et al., 2001).
