A bioassay on tissue cholinesterase activity of Rutilus kutum (Kamensky, ‎‎1901) exposed to some common pesticides in Iran

The toxicological effects of three commonly used pesticides in Iran on the fries of Caspian kutum (Rutilus kutum, Kamensky, 1901) were investigated through determining 50% lethal concentration (LC50) 96‑hr and cholinesterase (ChE) inhibition. The LC50 96-hr of carbaryl, glyphosate, and malathion were equal to 11.69, 6.64, and 0.97 mg L-1, respectively, that were considered as harmful (10.00-100 mg L-1), toxic (1.00-10.00 mg L-1) and very toxic (-1) compounds for this species. The exposure of fries to sub-lethal concentrations of the pesticides over 15 days indicated that the average of ChE activity in the head and trunk were 1086.89 ± 124.34 and 627.36 ± 99.60 mU min-1 per mg protein, respectively, with a significant difference relative to each other. There was a significant difference between fry exposed to all three pesticides and the control group in cholinesterase inhibition. The fries exposed to carbaryl (890.12 ± 28.08 mU min-1 per mg protein) and glyphosate (891.77 ± 31.61 mU min-1 per mg protein) showed lower ChE inhibition than those exposed to malathion (790.00 ± 58.14 mU min-1 per mg protein).