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Acute and (sub)chronic toxicity of the neonicotinoid imidacloprid on Chironomus riparius

Njattuvetty Chandran, Naveen, Fojtova, Dana, Blahova, Lucie, Rozmankova, Eliska, Blaha, Ludek
Chemosphere 2018 v.209 pp. 568-577
Chironomus riparius, aquatic organisms, chronic toxicity, ecosystems, glutathione, imidacloprid, insect development, insects, larvae, lethal concentration 50, lipid peroxidation, malondialdehyde, models, oxidative stress
Impacts of neonicotinoids on non-target insects, including aquatic species, may significantly influence ecosystem structure and functioning. The present study investigated the sensitivity of Chironomus riparius to imidacloprid exposures during 24-h, 10- and 28-days by assessing larval survival, growth, emergence and oxidative stress-related parameters. C. riparius exhibited high sensitivity compared to other model aquatic species with acute 24-h LC50 being 31.5 μg/L and 10-days LOEC (growth) 0.625 μg/L. A 28-days partial life cycle test demonstrated imidacloprid effects on the emergence of C. riparius. Exposure to sublethal concentrations during 10-days caused an imbalance in the reduced and oxidized glutathione (GSH and GSSG), and slightly induced lipid peroxidation (increased malondialdehyde, MDA). Our results indicate that oxidative stress may be a relevant mechanism in the neonicotinoid toxicity, reflected in the insect development and life cycle parameters.