Effects of cypermethrin on rainbow trout (Oncorhynchus mykiss)

Abstract

The aim of this study was to assess the effect of cypermethrin [(R,S)-α-cyano-3-phenoxybenzyl (1RS)-cis,tra-3-(2,2-dichlorovinyl)-2,2-dimethyl cyclopropane carboxylate] on rainbow trout (Oncorhynchus mykiss). The effect was assessed on the basis of the results of acute toxicity tests and on the comparison of results of haematological, biochemical and histopathological tissue examinations of a control and experimental group exposed to Alimetrine 10 EM pesticide preparation (active substance 100 g/l of cypermethrin). The acute semistatical toxicity test lasting 96 h was performed on rainbow trout juveniles. The 96hLC50 value of Alimethrine 10 EM was 31.4 µg/l. Examination of erythrocyte, leukocyte and biochemical profile and histopathological tissue examination was performed on 15 control and 15 experimental specimens of one-to-two-year-old rainbow trout after 96 h of exposure to Alimetrine 10 EM in the concentration of 31.4 µg/l. The experimental group showed significantly higher values (P < 0.01) of plasma ammonia (NH<sub>3</sub>), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), creatine kinase (CK), lactate (LACT) and significantly lower (P < 0.01) values of alkaline phosphatase (ALP) compared to the control group. Also, a significant decrease in count of developmental forms of myeloid sequence, and segmented neutrophile granulocytes in the experimental group were found. Teleangioectasiae of secondary gill lamellae and degeneration of hepatocytes were observed with histopathological examination. No histopathological changes were demonstrated in tissues (skin, spleen, cranial and caudal kidney) of rainbow trout following exposure to cypermethrine. The cypermethrine-based Alimethrinee 10 EM pesticide preparation was classified among substances strongly toxic for fish.