Safety and ecotoxicology of entomopathogenic bacteria

Bacillus entomopathogens, especially Bacillus thuringiensis, have been used extensively for control of insect pests in crops, forests, and the aquatic environment. Their safety for vertebrates and nontarget invertebrates has been thoroughly documented in a myriad of studies. Their short term effects on nontarget organisms that are unrelated to target insects is negligible. However, the effect of repeated applications on most ecosystems is relatively unknown. It is highly probable that any regular disruption of large insect communities, due to chemical or microbial insecticides or natural disaster, could have long term deleterious effects on higher trophic levels and ecosystem structure. The more diversified the food web, the less likely that complete or partial removal of a single species will result in catastrophic consequences. The more species a given intervention affects, the greater the likelihood of altering ecosystem structure. The safety and environmental impact of entomopathogenic bacteria should be evaluated in light of the risk for nontarget organisms in comparison with other interventions and the effect no treatment at all will have on an ecosystem.