Bioavailability of Agricultural Pesticides on the Land Snails in the Commune of Kérou in the North of Benin

Abstract

The present study was conducted in the commune of Kérou in North Benin to measure the bioavailability of agricultural pesticides heavily used in the production of cotton on snails. The test was conducted in peasant environment in two villages of the commune. In each site, there are three cages containing 6 snails each. The snails are exposed to soil and plants without special protection and are therefore exposed to environmental conditions. Firstly it’s to evaluate the presence or absence of agricultural pesticides in the viscera of snails after exposure. Secondly it consists to compare the different doses found in the viscera of snails in the different sites. And finally it’s to evaluate the effect of the toxicity of the pesticides on the reproduction of snails. The tests consisted of placing steel cages in the two experimental sites. In each site, there are three cages containing 6 snails each. Snails are exposed to soil and plants without special protection and are therefore exposed to environmental conditions. The observations were made in order to establish a study of transfer kinetics. After the analysis of the data, it appears generally that the accumulation of mineral elements highlighted is not proportional to the mineralogical composition of the soil in which the snail is exposed. Total nitrogen and nitrate were significantly accumulated in the flesh of site 2 snails compared to site 1 snails. These different measures show the bioavailability of soil minerals for living organisms. Accumulations are not necessarily accompanied by toxic effects in terms of survival for snails after 28 days of exposure. However, the absence of immediate toxic effect on snails does not imply a lack of effect in food chains due to the trophic availability of contaminants. The use of snails as bio-indicator of soil quality has therefore proved relevant in the context of soils polluted by minerals.