In a blind and randomised study, early postlarval stages of the tadpole shrimp Triops cancriformis, the fairy shrimp Branchipus schaefferi, and the clam shrimp Leptestheria dahalacensis were exposed to different concentrations of a commonly available Bti suspension, equivalent to 0, 4.5 (recommended treatment concentration), 45, 450, and 4500 AA/l. No statistically significant correlations were found between Bti concentration and mortality or longevity of the examined organisms.