Individual and interactive biochemical profile damages in Labeo rohita (Cyprinidae) by imidacloprid and clothianidin

Abstract

Neonicotinoid insecticide residues are found frequently in different water resources, but the knowledge of their ecological consequences is scanty. The present research focused on one-third of the LC50 concentration of the two neonicotinoids imidacloprid (66.6 mg/L) and clothianidin (30 mg/L) individually and a mixture (range of 33.3 + 15 mg/L) were exposed to Labeo rohita for 42 days. The investigation evaluated the single and combined insecticidal antagonistic effects on fish cholinesterases (AChE and BChE), oxidative stress activities, and DNA damage (8-OHdG) after intoxication. The imidacloprid (IMI), clothianidin (CLO), and combination intoxication significantly reduced AChE and BChE enzyme activities in the brain, muscle, and serum. The highest levels of AChE inhibition were found in the muscle and brain, whereas the highest levels of BChE were seen in the serum and muscle in the mixed group. The enzymatic and non-enzymatic oxidative activities in the brain and liver varied, with significant increases in superoxide dismutase, catalase activities, lipid peroxidation levels, glutathione S-transferase activity, and a decreasing trend in reduced glutathione levels compared to controls. The 8-OHdG activity increased significantly in proportion to exposure time, while the liver showed the highest increase, followed by the brain in the mixture group. Long-period exposure to neonicotinoids can cause severe neurotoxicity by inhibiting cholinesterase, altering antioxidant activities, and inducing DNA damage (increasing 8-OHdG). The results showed that clothianidin is more toxic than imidacloprid as a single active ingredient, whereas the mixture of two insecticides is more toxic than the single active ingredients.