Acute exposure to chlorpyrifos and glyphosate induces changes in hemolymph biochemical parameters in the crayfish, Astacus leptodactylus (Eschscholtz, 1823)

Abstract

Acute and subacute toxicity tests for chlorpyrifos and glyphosate were performed on the crayfish, Astacus leptodactylus. The crayfish were divided into a control group and four experimental groups with exposure from 50.18 to 301.11 μg L^-1 of chlorpyrifos for 96 h under semi-static test conditions. In the same experiment, the crayfish were exposed to different concentrations of glyphosate (from 0.0, 8.14 to 13.05 mg L^-1) for 96 h. Mortality was recorded, and the median lethal concentrations (LC₅₀) were calculated using probit analysis. The 96 h LC₅₀ values of chlorpyrifos and glyphosate to A. leptodactylus were 49.55 ± 4.66 μg L^-1 and 7.83 ± 0.50 mg L^-1, respectively. The results showed that chlorpyrifos was a few hundred times more toxic than glyphosate for the crayfish. Then, the crayfish were exposed to different subacute concentrations of chlorpyrifos (12.5 and 25 μg L^-1) and glyphosate (2 mg L^-1 and 4 mg L^-1) for seven days, and their toxicity was evaluated through several hemolymph biochemical parameters. Chlorpyrifos and glyphosate exposure caused a significant (P < 0.01) increase in the activity of lactate dehydrogenase (LDH), and gamma-glutamyl transferase (GGT). The results showed a significant (P < 0.01) decrease in acetylcholinesterase (AChE), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and phenoloxidase (PO) activities in the hemolymph of the crayfish exposed to chlorpyrifos and glyphosate. The total protein and cholesterol levels showed a significant decrease (P < 0.01) in the hemolymph of the crayfish after seven days of exposure to chlorpyrifos and glyphosate. There was a significant increase in triglycerides and glucose levels in treated crayfish. These results show that chlorpyrifos is highly toxic, while glyphosate is moderately toxic to A. leptodactylus. According to the results, subacute concentrations of chlorpyrifos and glyphosate could lead to a collapse of cellular homeostasis and changes in the hemolymph biochemical parameters in the crayfish. Physiological changes caused by exposure to chlorpyrifos and glyphosate in A. leptodactylus may have direct effects on the survival of these organisms.

Keywords: Acute toxicity; Biochemical parameters; Crayfish; Herbicide; Pesticide.