The present study was conducted on cattle egret(Bubulcus ibis)as it was noticed a high incidence of mortality of it in a residential agricultural area, due to exposure to pesticide application (monocrotophos, thiobencarb,fluroxypyr and butachlor) in Kafr El-Sheikh Governorate. Thisworkwasschemed to emphasize the main cause of toxicity induced by pesticides as well as some heavy metals as predisposing causes.
In this study 32 adult (o.3-o.5kg)alive cattle egrets exposed to these pesticides and 8 birds from pastures non-exposed to pesticides acted as controls for comparison, were caught and examined for blood pictures and blood biochemistry. Also, pesticide residues and some heavy metals were determined in mud or soil, internal organs (liver, kidney, brain, ovaries, testes)and tissues of muscles, skin and feathers of contaminated birds. Birds exposed to pesticides showed anemia which manifested by a marked drop in RBCs, Hb content and PCV% as a result of a disturbance in the hemopoietic system. Meanwhile, leucocytosis, neutrophilia, monocytosis and lymphopenia were recorded in polluted birds which reflect a disturbance in the immune system in response to intoxication.However, basophils, eosinophils showed non-significant variation compared to controls. Elevation levels of AST, ALP, and uric acid were observed in the serum of polluted birds in comparison to control values, indicating the hepatorenal dysfunction. Nevertheless, serum values of ALT and creatinine did not alter.
Considerablepesticideresiduesweremeasured in mud and examined organs and tissues of contaminated birds. For exception, thiobencarb and butachlor could not be detected in the testes. The concentration levels of some heavy metals (pb, Cd,Cu,Zn,Mn,Ni) were determined in mud,organsandtissuesof pollutedbirds.Pb,ZnandNishowed theoverall concentrations followed by Cu and Mn. Whereas, Cd levels could be detected only in kidney and brain, while Mn was found in liver only.
It isconcluded from the current study that pesticides exhibited rapid deleterious effects on exposured cattle egrets which implicated signifi-cantlyimpairing function of liver and kidney as well as overt disorders in hsaemopoietic system as compared to respective controls.Despite of some heavy metals as well as bioconcentration of pesticide residues in organs and tissues reflect continuous toxicity.
It's inferred that the mortality of wild cattle egret is a biomarker of environmental pollution by pesticides.