COMPARATIVE TOXICITY OF 4 INSECTICIDES, INCLUDING IMIDACLOPRID AND TEBUFENOZIDE, TO 4 AQUATIC ARTHROPODS

The tolerance of four aquatic organisms to four chemicals (aldicarb, d imethoate, imidacloprid, and tebufenozide) was determined using 48-h a cute toxicity tests at 27 degrees C. Species included two saline (Arte mia sp. and Aedes taeniorhynchus (Wiedemann)) and two freshwater (Daph nia magna Straus and Aedes aegypti (L.)) organisms. Temperature was al so evaluated as a toxicity modifying factor for the freshwater species . Two selective insecticides (imidacloprid and tebufenozide) were comp ared 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 cond itions. Both aldicarb and dimethoate caused neurotoxicity in all organ isms tested. Mortality associated with molting suggested that tebufeno zide affected the molting process of all organisms, causing the format ion of an incompletely sclerotized head capsule and the failure of ecd ysis in the mosquito species. These responses resulted in lethal larva l molts. Imidacloprid, on the other hand, caused delayed symptoms of g eneral nerve poisoning compared with the two acetylcholine esterase in hibitors. Our results suggest that both tebufenozide and imidacloprid would be selective insecticides that can be used with reasonable envir onmental safety toward nontarget aquatic crustaceans. There was a grea ter correlation of susceptibility to test chemicals within taxonomical ly close organisms than between organisms that share habitats.