How Synthetic Pyrethroid 1-Trans Phenothrin Affects Freshwater Mussel, Unio delicatus: Biochemical and Histological Responses.

Abstract

1-Trans phenothrin (CAS no: 26046-85-5;3-phenoxybenzyl (1R,3R)-2,2-dimethyl-3-(2-methylprop-1-enyl)) cyclopropanecarboxylate, a synthetic pyrethroid insecticide, is widely used in agriculture for crop protection, household insects, and human louse infestation. Freshwater mussels (Unio delicatus Lea, 1863) were exposed to 1-trans phenothrin at concentrations of 1/10 (814 μ/L) and 1/100 (81.4 μ/L) of the 96-h LC₅₀ value for 96 h and 21 days. Total hemocyte counts (THCs), total antioxidant status (TAS), total oxidant status (TOS), sodium-potassium adenosine triphosphatase (Na⁺/K⁺-ATPase), and acetylcholinesterase (AChE) activities of the gill and digestive gland tissues of freshwater mussels were measured. Biochemical responses did not show any significant change in the solvent control group relative to the control (p > 0.05). Na⁺/K⁺-ATPase activity of the gills decreased at both low and high concentrations of 1-trans phenothrin at the end of both experimental periods compared to the control group. Additionally, AChE activity decreased in the gills and digestive glands at all experimental concentrations by the end of the trial periods compared to the control group (p < 0.05). Under the effect of 1-trans phenothrin, TAS levels decreased in the gills, while they increased in the digestive glands during both exposure periods (p < 0.05). In both tissues, TOS levels increased at 814 μg/L 1-trans phenothrin on the 21st day compared to the control group (p < 0.05). The gill and digestive gland tissues were affected histopathologically. THCs increased at 96 h under exposure to 81.4 μg/L and 814 μg/L 1-trans phenothrin compared to the control group, whereas they decreased on the 21st day. This study demonstrated that 1-trans phenothrin causes toxicity by affecting the biochemical parameters of freshwater mussels (U. delicatus).