Effect of the biopesticide Bacillus thuringiensis (Berliner, 1911), strain 344, on indicators organisms of the aquatic compartment

Bacillus thuringiensis (Berliner, 1911) (Bt) is a bacterium which contains endotoxins with insecticide action against several insect pests. Bt and other biopesticides are usually known as innocuous to non-target organisms, although some adverse effects have been described. In this work it was evaluated the effect on aquatic organisms of different trophic levels due to the exposure to the 344 strain of Bt (Bt344). The test-organisms were exposed to concentrations corresponding to more than 1,000 fold the application rate of biopesticide which is capable to control the corn worm Spodoptera frugiperda. Bt344 did not alter the growth patterns of the algae Pseudokirchneriella subcapitata. It was observed a significant mortality (8.9%) for the fish Hyphessobrycon scholzei, but it is lower than the allowed limit of mortality for the control (10%). Nevertheless, biopesticide exposure reduced the survival of Dapnhia similis (44.8% less than the control survival), which suggests a risk for aquatic invertebrate species.