The Effect of Diazinon on Haematological Indices of Common Carp (Cyprinus carpio L.)

The goal was to assess an effect of diazinon [0,0-diethyl 0-(2-isopropyl-6-methylpyrimidin-4yl) phosphorothioate] on common carp (Cyprinus carpio L.).The effect was assessed based on results of acute toxicity tests and on a comparison of results of haematological examination of a control and an experimental group exposed to Basudin 600 EW pesticide preparation (active substance 600 g.l -1 of diazinon).The acute toxicity test lasting 96 h was performed semistatically on common carp juveniles.Examination of erythrocyte and leukocyte profile was performed on 15 control and 25 experimental specimens of one-to-two-year-old common carp after 96 h of exposure to Basudin 600 EW in concentration of 32.5 mg .l -1 .The 96hLC50 value of Basudin 600 EW for common carp juveniles was 26.7 mg .l -1 .The experimental group of one-to two-year-old common carp showed significantly lower values (p < 0.01) of erythrocyte count (RBC), haemoglobin content (Hb) and haematocrit (PCV) compared to the control group.Values of MCV, MCH and MCHC were comparable in both groups during the study.In contrary, there was a significant decrease in leukocyte count (Leuko) (p < 0.01), as well as in both the relative and absolute lymphocyte count (p < 0.01) and a significant increase in both the relative and absolute count of developmental forms of neutrophile granulocytes: myelocytes (p < 0.01) and metamyelocytes (p < 0.05) in the experimental group.Relative and absolute count of monocytes and both the band-and segmented neutrophile granulocytes was comparable in both groups during the study.The diazinon-based Basudin 600 EW pesticide preparation was classified among harmful substances for fish.Changes in values of both the erythrocyte and leukocyte profile after exposure to diazinon-based preparation may be refered to disruption of haematopoiesis as well as to a decrease on non-specific immunity of the fish. Organophosphorous pesticide, acute toxicity, erythrocyte profile, leukocyte profileOrganophosphorous pesticides have fully replaced the persistant chlorinated pesticides in the 1970's and on the beginning of 1980's.The main advantage of the organophosphorous pesticides was their low cummulative ability and short-term persistance in the environment.Although the organophosphorous pesticides have been replacing by pyrethroid-based pesticides within the last 10-15 years, there is still a very intensive utilization of organophosphates.Organophosphorous pesticides are also utilized in fish culture (mainly those based on dichlorvos and trichlorfon) in order to suppress some parasitary diseases such as monogeneoses and arthropodoses (Noga 1995;Schlotfeldt and Alderman 1995; â í t e k et al. 1998;Navrátil et al. 2000).Nevertheless, the pesticide preparations are considered harmful for fish in most cases (Svobodová et al. 1998).Diazinon is a common active substance of organophosphorous pesticides (Roberts and Hutson 1998).Scholz et al. (2000) reported that not all of its effects to fish organism are known, despite of its very intensive use.Although the aquatic environment is not the main target and the aquatic invertebrates are not the target organisms, presence of diazinon in water was reported and its negative effect to aquatic organisms is proven.The ELISA assay