Comparison of acute toxicity of two neonicotinoid insecticides, imidacloprid and clothianidin, to five cladoceran species

The authors examined the acute toxicity of clothianidin to the cladocerans (Ceriodaphnia dubia, C. reticulata, Daphnia magna, D. pulex, and Moina macrocopa) and compared them to results from imidacloprid toxicity testing. The tests were performed using the formulated products Dantotsu (clothianidin) and Admire (imidacloprid). Female neonates from each species were tested for acute 48-hour immobilization under static conditions to determine the EC50. The clothianidin EC50s were: C. dubia - 1,691.3 µg/L; C. reticulata - 29,474 µg/L; D. magna - 67,564 µg/L; D. pulex - 31,448 µg/L; and M. macrocopa - 61,106 µg/L. These compare to earlier testing by the authors that found imidacloprid EC50s of: C. dubia - 571.62 µg/L; C. reticulata - 5,552.9 µg/L; D. magna - 43,265 µg/L; D. pulex - 36,872 µg/L; and M. macrocopa - 45,271 µg/L. Their results showed that the variation in EC50 values between imidacloprid and clothianidin were between a factor of 80 and 40 for all but C. dubia, suggesting that the compounds have very different effects on the species. Their comparison of cladoceran testing with published results on other aquatic species suggested that other taxa are about 2,000 times more sensitive to the neonicotinoids.

Hayasaka, D., K. Suzuki, T. Nomura, M. Nishiyama, T. Nagai, F. Sanchez-Bayo, and K. Goka
Journal of Pesticide Science
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