Haematological Changes in Labeo rohita (H.) due to Exposure of Pesticides, Difenoconazole and Thiamethoxam
As pesticide's pollution is a very common phenomenon in aquatic environment of Bangladesh, an attempt has been made to investigate the changes in haematological parameters of Labeo rohita (H.) due to exposure of two pesticides, difenoconazole and thiamethoxam for a period of 96 hrs (from 12th to 15th August, 2016) in the Laboratory of Department of Fisheries, University of Rajshahi, Rajshahi, Bangladesh. Two experiments were conducted in eighteen glass aquaria under 3 treatments (T1, T2 and T3) in each experiment. In both experiments, T1 was assigned to the fish treated as control; in experiment-1, T2 and T3 were assigned to the fish treated with difenoconazole at 0.002 and 0.0.004 ml/L, respectively and in experiment-2, T2 and T3 were assigned to the fish treated with thiamethoxam at 0.05 and 0.10 mg/L, respectively. In this study, physico-chemical parameters (temperature, dissolved oxygen and pH) of test water, behaviour and haematological parameters (WBC, RBC, Hb, PCV, MCV, MCH and MCHC) of the fish were analyzed with standard methods. During the study period, there was no significant difference in the physico-chemical parameters of test water among the treatments and were within the suitable ranges. When the fish exposed to the pesticides, their food intake decreased primarily, exhibited restlessness and sluggish swimming behavior. When the fish exposed to Difenoconazole, the total count of WBC and RBC, and the values of Hb, PCV and MCV decreased whereas the MCH and MCHC values increased in the fish of T2 and T3 compared to the control fish. On the other hand, when the fish exposed to Thiamethoxam, the total count of WBC and RBC decreased in the fish of T2 and T3 compared to the control fish. The Hb level in the fish of T2 showed minute decrease but in the fish of T3 significantly increased. The values of PCV, MCH and MCHC in the fish of T2 and T3 were significantly increased but MCV values showed decrease in the fish of T2 and T3. Therefore, the present study concluded that the exposure of difenoconazole and thiamethoxam pesticides produce an adverse effect in haematological parameters of the fish.
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