Unintended effects of Bacillus thuringiensis spores and Cry toxins used as microbial insecticides on non-target organisms

Bacillus thuringiensis (Bt) microbial insecticides owe their effectiveness mostly to Cry toxins that target specific insects. Bt products are made of spores of Bt and crystals of toxins, Cry toxins being also used in genetically modified crops. Although widely used in agriculture, data on their long-term effects are scarce. Because microbial insecticides are essential to the development of sustainable agriculture, more research is needed to understand the unintended effects of Bt products and to improve Bt products and applications, ultimately leading to safer agricultural practices. In this review, we focus on recent studies dealing with the persistence and unintended effects of the main components of Bt insecticidal products, namely Cry toxins, spores and vegetative cells.