Physiological and biochemical responses of Labeo rohita to neonicotinoids imidacloprid, clothianidin, and their mixture.

Abstract

Neonicotinoids, widely used insecticides, pose severe environmental risks due to their persistence in soil and water, adversely affecting non-target organisms and ecosystem integrity. The present study examined the 56 days effects of imidacloprid (66.6 mg/l), clothianidin (30 mg/l), and their combination (33.3 mg/l and 15 mg/l) on Labeo rohita, using one-third of the LC₅₀ sub-lethal concentrations. Survival, weight gain, and the hepatosomatic index decreased insignificantly in the IMI group and significantly in the CLO and Mix groups. Haematological indicators, including erythrocyte counts, haemoglobin, and haematocrit values, were also significantly reduced. Blood glucose and serum creatinine levels increased, while serum albumin, globulin, and plasma total proteins decreased. White blood cell counts elevated, while immunoglobulin (IgM), respiratory burst, and lysozyme activities were significantly inhibited. Liver, brain and muscle lactate and malate dehydrogenases were elevated, whereas succinate and glutamate dehydrogenases were decreased. Liver aspartate aminotransferase activity was substantially higher than that of brain and muscle, which had considerably higher levels of alanine aminotransferase in muscle than in the brain and liver. Additionally, muscle alkaline phosphatase activity was significantly higher than in the liver and brain, whereas liver acid phosphatase showed a greater elevation than in the muscle and brain. The physiological, haematological, and biochemical indices peaked on day 28 and slight recovery was observed on day 56 (IMI > CLO > Mix). The study highlights that the mixture of insecticides poses greater hazards compared to a single active compound, and the indiscriminate use of these insecticides jeopardizes non-target organisms, ecosystems, and public health.