Imidacloprid impacts oxidative stress and neurotoxic biomarkers in different marine organisms (fish, mysid and clamworm)

Abstract

Imidacloprid (IMI) is the most widely used neonicotinoid insecticide worldwide and it has been detected in various aquatic ecosystems, including marine ecosystems. Although much information is available about the effects of IMI on organisms, studies of IMI sublethal effects on marine fish, mysids and clamworms are lacking. Thus, three marine model organisms (Oryzias melastigma, Neomysis awatschensis, and Perinereis aibuhitensis) were used to evaluate the activities of acetylcholinesterase (AChE), superoxide dismutase (SOD), glutathione S-transferase (GST), catalase (CAT) and the content of malonaldehyde (MDA) as biomarkers after 21 days of exposure to IMI. The activities of biomarkers were measured using an enzyme-labeled instrument, and the degree of biological hazard was analyzed using the integrated biomarker response (IBR) index method. Results demonstrated that oxidative stress and neurotoxic biomarkers of different organisms had different trends with increasing IMI concentration but MDA content was consistently induced by IMI. The no observed effect concentrations (NOECs) of AChE, SOD, CAT, GST and MDA were 1.2, 2.3, < 1.2, 2.3 and 1.2 mg/L for O. melastigma, 0.7, < 0.3, < 0.3, 0.3 and < 0.3 μg/L for N. awatschensis, and 0.7, 0.7, 0.7, < 0.7 and 1.5 μg/L for P. aibuhitensis. The IBR results indicated that 18.5 mg/L, 5.3 μg/L and 11.6 μg/L of IMI were the most toxic for O. melastigma, N. awatschensis and P. aibuhitensis, respectively. Changes in these biomarkers provide early warning of fish, mysids and clamworms stress, suggesting that investigating the hazards of neonicotinoid pesticides to marine organisms is worthwhile.