Integrated biomarker response in common carp fingerlings exposed to neonicotinoid insecticide imidacloprid

Imidacloprid (IMI) is a systemic insecticide classified as a neonicotinoid, which targets the central nervous system of insects. This insecticide is commonly used to protect crops from sucking pests like ticks, whiteflies, plant hoppers, and leafhoppers. There are reports of IMI having highly toxic consequences on non-targeted organisms like bees, humans, and aquatic animals. However, information regarding adverse effects of long-term exposure of different commercial products containing IMI as an active compound on non-targeted animals is very scanty. Therefore, current research effort aims to determine toxicity effects of commercial-grade Premise, 30.50%, Suspension Concentrate (SC) containing IMI as an active compound on freshwater experimental fish Cyprinus carpio using an integrated biomarker approach. Fish were semi-statically exposed to 17.36, 20.38, and 26.04 mg/L of IMI, which corresponds to 1/12, 1/10, and 1/8 of 96 h Lethal Concentration (LC₅₀ i.e. 208.3 mg/L) for 28 days. Results showed significant changes in haemato-immunological, serum biochemicals, and antioxidant enzymes upon 28 days of exposure. IMI exposure induced ROS (Reactive Oxygen Species) production, increased malonaldehyde (MDA) content in liver and gill tissues and subsequently reduced acetylcholinesterase (AChE) activity in brain tissue. Moreover, assessment through micronuclei (MNi) test was suggestive that the tested product is genotoxic, which was evident through the induction of significant numbers of micronuclei formation in erythrocyte cells of the test organisms. From the present study, it is obvious that the commercial formulation of IMI, Premise, can also act as a potential immunosuppressor and oxidative stress enhancer and can trigger probable neurotoxic and genotoxic effects that may result in physiological imbalances. Thus, it might become imperative to focus the toxicity studies not only on analytical grade but also on commercial products containing IMI as an active compound in non-targeted organisms. The study also underscores the importance of sustainable pest management practices to protect non-target species and maintain ecosystem balance, ultimately safeguarding public health and promoting environmental conservation.