Sublethal effects of selected herbicides and pesticides on selected members of subfamily Schizothoracine

Abstract

Agrochemicals are used in the agricultural field to control the pest and unwanted herbs to increase the crop productivity but they pose adverse affects beyond the pest and herbs eradication. In this study the sub-lethal effects of four different agrochemicals (Atrazine, Pendimethalin, Chlorpyrifos and Cypermethrin) on three members of subfamily schizothoracine (Schizothorax plagiostomus, Schizothorax labiatus and Schizothorax esocinus) on hematological, biochemical, histological profiles and genotoxicity was assessed. Fishes were treated with different sub-lethal concentrations of Atrazine and Pendimethalin (1 ppm, 2 ppm, 3 ppm and 4 ppm) and Chlorpyrifos and Cypermethrin (1 ppb, 2 ppb, 3 ppb and 4 ppb) for 96 hours. Results showed that these agrochemicals cause alterations in hematology in such order; Atrazine> Pendimethalin> Cypermethrin> Chlorpyrifos. Alterations in biochemical profile were also observed. The toxicity order for electrolytes is Chlorpyrifos> Pendimethalin> Cypermethrin> Atrazine, whereas the toxicity order for metabolites exposed to herbicides and pesticide is Atrazine> Pendimethalin> Cypermethrin> Chlorpyrifos and the toxicity order for enzymes is Atrazine> Pendimethalin> Cypermethrin> Chlorpyrifos. In histopathological analysis, gills exhibited pyknosis, accumulation of mucus, lamellar destruction, fusion, curling, disruption and shortening of lamellae. Brain histology showed pyknosis, degenerative changes, necrosis, hemorrhage, mild degenerative changes, structural degeneration and vacuolar changes. Intestine histology showed necrosis, blood congestion, ulceration of mucosa, destructive changes, shrinkage of columnar epithelial and damage of columnar epithelial cells. Kidney histology exhibited vacuolation, vacuolization of epithelial lining, interstitial hemorrhage, increased interstitial space, interstitial hemorrhage, multifocal granulomas and interstitial edema. Liver histology showed pyknosis, densely packed hepatocytes, necrosis, blood congestion, bile pigment, disappearance of hepatic cell wall, vacuolization, hepatocellular infiltration and perivascular edema. Muscles histology show muscles necrosis, fragmentation of xxi sarcoplasm and calcified muscles. Increase in genotoxicity was observed in all species exposed to selected agrochemicals. The toxicity order of agrochemicals causing DNA damage was Atrazine> Chlorpyrifos> Cypermethrin> Pendimethalin. It could be concluded from this study that Atrazine, Pendimethalin, Chlorpyrifos and Cypermethrin are very toxic and pose life threatening impacts on the quality of fish. Therefore, it is recommended that the use of Atrazine, Pendimethalin, Chlorpyrifos and Cypermethrin should be minimized by making use of less toxic chemicals or biological control for pests and insects.