Comparative toxicity of four insecticides, including imidacloprid and tebufenozide, to four aquatic arthropods
1997
Song, M.Y. | Stark, J.D. | Brown, J.J.
The tolerance of four aquatic organisms to four chemicals (aldicarb, dimethoate, imidacloprid, and tebufenozide) was determined using 48-h acute toxicity tests at 27 degrees C. Species included two saline (Artemia sp. and Aedes taeniorhynchus (Wiedemann)) and two freshwater (Daphnia magna Straus and Aedes aegypti (L.)) organisms. Temperature was also evaluated as a toxicity modifying factor for the freshwater species. Two selective insecticides (imidacloprid and tebufenozide) were compared with two broad-spectrum insecticides, aldicarb and dimethoate. In general, A. taeniorhynchus was the most susceptible, and Artemia sp. was the most tolerant to insecticides used under our experimental conditions. Both aldicarb and dimethoate caused neurotoxicity in all organisms tested. Mortality associated with molting suggested that tebufenozide affected the molting process of all organisms, causing the formation of an incompletely sclerotized head capsule and the failure of ecdysis in the mosquito species. These responses resulted in lethal larval molts. Imidacloprid, on the other hand, caused delayed symptoms of general nerve poisoning compared with the two acetylcholine esterase inhibitors. Our results suggest that both tebufenozide and imidacloprid would be selective insecticides that can be used with reasonable environmental safety toward nontarget aquatic crustaceans. There was a greater correlation of susceptibility to test chemicals within taxonomically close organisms than between organisms that share habitats.
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