Histopathological effects of methomyl and crude extracts of Jatropha curcas against the terrestrial snail, Monacha obstructa (Gastropoda:Hygromiidae)

Background: The negative effect of over-reliance on the use of synthetic pesticides have led to the search for natural alternatives to pest control. This study was designed to evaluate the toxicity effect of the crude plant extracts of Jatropha (Jatropha curcas Linn.) seeds in comparison with methomyl on some histopathological changes of the terrestrial snail species Monacha obstructa (Pfeiffer, 1842). The toxicity effect of methomyl and crude extracts of ethanol and acetone extracts of Jatropha curcas seeds were determined on some histological changes of the land snail, Monacha obstructa at four concentrations using the contact technique under laboratory conditions. Results: The results revealed that the crude extracts of Jatropha exhibited obvious adequate effects compared with methomyl against M. obstructa land snails. The highest toxicity effects were obtained by methomyl followed by the ethanolic extract of Jatropha and hexane extract of Jatropha. The histopathological effect of LC50 of Jatropha crude extract and methomyl on the digestive gland and foot tissues were examined in the land snails M. obstructa. The treated snails showed several histological changes in the digestive gland and foot compared with the control group snails. The histological examinations of the digestive tubules included destroyed and detached in the outer layer covering digestive tubules. In addition, marked increase in the width most of the digestive tubules lumen. The intertubular connective tissue between the digestive tubules showed great destruction, while the foot of treated snails showed rupture of the epithelium covering the foot and desquamation of the epithelium. We also observed the presence of areas of connective tissue necrosis and destruction of the muscular tissue. Conclusions: It has been found that extracts of Jatropha seeds have a toxic activity that caused histopathological damage that led to the death of land snails, and thus it can be recommended as a source for the development of molluscicides.