BINDU VIJAYAKUMARI SUDHAKARAN AND SREEJA S.
Abstract
Chlorpyrifos is classified as an organophosphorus pesticide that exhibits properties of being a broad-spectrum insecticide, acaricide, and nematicide. It is characterized by its ability to degrade quickly and its non-persistent nature. The current investigation involved the determination of the LC50 value of chlorpyrifos on A. testudineus. The computed LC50 values were found to be 11.59, 8.82, 6.30, and 3.82 ppm for exposure durations of 24, 48, 72, and 96 hours, respectively. The levels of protein and glycogen in the stomach, gut, and muscle of A. testudineus, which were subjected to a concentration of 3.82 ppm (LC50 96 hours) chlorpyrifos for a duration of 96 hours, exhibited a notable reduction when compared to the control group. The stomach sections of A. testudineus, when subjected to a concentration of 3.82 ppm chlorpyrifos for a duration of 96 hours, exhibited degeneration of the mucosa layer and necrosis of the mucosa epithelium. The histopathological examination of the intestine revealed several notable findings, including the presence of a disintegrating serosa, a significantly enlarged muscularis layer, and observable damage to both the circular muscle layer and submucosa. Additionally, evidence of necrosis was observed within the mucosa layer. The muscle tissue exhibited degeneration inside the muscle bundles, characterized by the presence of discrete regions of necrosis and the development of vacuoles within the muscle bundles. The results of this study demonstrate that chlorpyrifos exhibits a significant level of toxicity towards A. testudineus, and it is important to note that the absence of mortality does not guarantee the maintenance of physiological well-being in this particular fish species.