Effect of acute toxicity of Dimethoate on some organs of mosquito fish, Gambusia affinis hollobrokii

Abstract

This study aimed to calculate the LC50 of Dimethoate in case of G. affinis hollobrokii as a result of exposure to different concentrations of Dimethoate (DM). The exposure was continued to 96h. with concentrations of 30, 60, 90 mg/L and control group. The results showed that the calculated LC50 of Dimethoate in case of G. affinis hollobrokii equal to 63.33 mg/L. The mortality increases with the increasing of concentrations.From investigate the histopathological alterations induced in some organs (gills, liver and Kidney) of Gambusia affinis hollobrokii as a result of exposure to 90 mg/L of Dimethoate (DM) and control group for 96h.. The microscopic examination of gill tissue of the fish exposed to 90 mg/L of Dimethoate pesticide showed hyperplasia and hypertrophy of the epithelial cells in secondary gill lamellae with partial oedema, lifting up epithelial layer, atrophy of the secondary lamella and congested blood vessels. Liver tissue of the same group of fish showed that, the liver architecture was destroyed, congestion of blood vessels, fatty degeneration in hepatocytes and appearance of some necrotic areas. Kidney tissue showed degenerated renal tubules, severe congestion of the blood vessels, fluid stagnation in renal tubules, oedema, necrotic of renal tubular cells and macrophage leucocytes were also detected. A total of 40 specimens of mosquito fish, Gambusia affinis hollobrokii with a good condition were obtained from El-Saidah Eisha at Cairo Governorate during April, 2015. Fish were transported to the fish laboratory at Animal House of Zoology Department, Faculty of Science, Al-Azhar University; in large plastic bag containing approximately 20 L of water and a lot of oxygen. In the laboratory, fish were acclimatized for one week in well aerated large glass tank (100x 50x 50 cm) and fed daily on a commercial fish diet ad libitum, before the beginning of the experiment.