The use of chemical insecticides for the control of insect pests has proven very effective at increasing today’s productivity in agriculture and forestry.  The heavy use of chemical insecticides, however, has not been without severe drawbacks.  These have prompted the development of alternative methods for the control of insect pests.  Bacillus thuringiensis (Bt) is a bacterium that expresses some specific insecticidal activities.  Several Bt-based commercial formulations have been developed and they now account for 95% of the world market of microbial pest control agents.

After an Introduction to Bacillus thuringiensis, the δ-endotoxins, the mode of action, and the development of the commercial use of Bt products, this document will focus on the ecological impacts of the use of conventional Bt-based commercial formulations.  These are: the environmental fate of Bt on foliage, in soil, and in water; the effects of Bt on soil, water, plants, and non-target microorganisms, and on invertebrates (non-target lepidopterans, honey bees and other invertebrates) and vertebrates (fishes, amphibians, reptiles, birds, and mammals), including human beings.