Chlorpyrifos-induced Histopathological Alterations in Duttaphrynus melanostictus (Schneider 1799) Tadpoles: Evidence from Empirical Trials

Abstract

This paper reports the histopathological responses of the gill, liver and tail muscle tissues in tadpoles of the Asian Common Toad Duttaphrynus melanostictus (Schneider, 1799) exposed to chlorpyrifos a common organophosphorus pesticide. Tadpoles of Gosner stages 24-26 were continuously exposed to low, mid and high (500, 1000 and 1500 µgl -1 ) concentrations of chlorpyrifos for two weeks. Histological alterations in the tissues of the surviving larvae were microscopically examined both at the end of the exposure period and after a week following the final exposure. Several histological alterations were noted in the gills, liver and tail muscles of the larvae exposed to 1500 µgl -1 of chlorpyrifos. The gills of exposed larvae showed architectural distortion resulting from reduced primary and secondary gill lamellae and blood vessels, and alterations in the gill epithelium. In the liver sinusoidal congestion and dilation, cytoplasmic vacuolation and changes in hepatocytes such as hyperchromatic nuclei and nuclear fragmentation were observed. The tail muscle tissue suffered from severe atrophy and myotomal disintegration. Although histological alterations in the gill and liver tissues were noted only at the high concentration, changes in the muscle tissue i.e. muscle degeneration and atrophy, were apparent at both low and mid concentrations. The degree of damage in surviving larvae in a week following the final exposure was lower than that observed during the exposure, probably indicating recovery or resistance. The findings of the present study emphasize the need to investigate possible sublethal damage induced by pesticides in amphibians inhabiting agricultural habitats.

Chronic exposures to fungicide pyrimethanil: multi-organ effects on Italian tree frog (Hyla intermedia)

“…The dilation and congestion of blood vessels and sinusoid were one of the most evident results of pyrimethanil application. Similar findings were reported in several amphibian species after exposure to both pesticides and heavy metals 34 , 53 , 54 . Some authors suggested that endothelial cells alterations may affect the blood flow from the hepatic artery and veins to the central vein thus resulting in extravasations of red blood cell and sinusoids dilation 53 , 55 .…”

“…Similar findings were reported in several amphibian species after exposure to both pesticides and heavy metals 34 , 53 , 54 . Some authors suggested that endothelial cells alterations may affect the blood flow from the hepatic artery and veins to the central vein thus resulting in extravasations of red blood cell and sinusoids dilation 53 , 55 . We also showed a remarkable liver tissue dyschromia highlighting the establishment of different pathologic response in the same tissue.…”

Cytotoxicity Evaluation of the East Asian Bullfrog (<i>Hoplobatrachus rugulosus</i>) in an Agricultural Area Affected by Chlorpyrifos

“…Exposure to chlorpyrifos led to smaller body sizes and delayed maturation in Rana boylii tadpoles (Sparling and Fellers 2009). Moreover, it induces histopathological changes in the gills, liver, and tail of tadpoles of the Duttaphrynus melanostictus species (Bandara et al 2012). Chlorpyrifos is usually found in agricultural areas and may directly affect aquatic ecosystems.…”

Cocktail effect of Profenophos and Abamectin on tadpoles of Asian Common Toad (<i>Duttaphrynus</i> <i>melanostictus</i>)

“…In Sri Lanka, it is found all over the country and occurs up to elevations of about 1700 m (Manamendra-Arachchi and Pethiyagoda, 2006). It is more abundant in human altered habitats such as agricultural landscapes and urban settings (Bandara et al, 2012). Duttaphrynus melanostictus is distinguished from all the other Sri Lankan Duttaphrynus species because of the absence of parietal ridges and the presence of two longitudinal rows of large warts which distributed all length of inter parotid area.…”