ACUTE TOXICITY OF SELECTED PESTICIDES TO THE ESTUARINE SHRIMP LEANDERTENUICORNIS (DECAPODA, PALAEMONIDAE)

The shrimp Leander tenuicornis is abundant in southeastern Queensland intertidal marsh pools and was chosen as an indicator species for toxi cological studies with pesticides. Acute toxicity to this crustacean o f temephos and 3 pesticide compounds under evaluation for registration in Australia (Bacillus thuringiensis var. israelensis, s-methoprene, and pyriproxyfen) was tested in 96-h laboratory trials. Temephos was t he most toxic compound, with a median lethal concentration (LC(50)) of 0.01 ppm (0.33 times the estimated field concentration [EFC] for a 15 -cm-deep pool). s-Methoprene was the least toxic compound, with an LC( 50) of 14.32 ppm (1,790 times the EFC). Bacillus thuringiensis var. is raelensis and pyriproxyfen produced LC(50) values of 60.9 x 10(6) ITU (176 times the EFC) and 0.098 ppm (12.25 times the EFC), respectively.