Impact of Varying Herbicide Contaminated Soil on Biomarkers of <I>Achatina achatina</I>

Soil microrganisms or faunas play vital roles in biogeochemical cycles which maintain the state of equilibrium of mineral elements in soil ecosystem as well as impacting on its texture and structure in otherward productivity. The impact of herbicides on biological population of soil samples spiked with various herbicides such as: dragon (paraquat) dichloride, Action 40 (Dimethoate), Vanish (Glyphosate). Buta force (Butachlor) and Amino force (2, 4-D amine 720G/L) were investigated. The soils were spiked with 10% of the herbicides, incubated for 4weeks and the oxidative stress as well as the acetylcholinesterase activity of soil faunas used as biomonitors. There was a progressive increase of lipid peroxidation in achatina achatina with vanish having the highest level of malondialdehyde (5.12 mg.dl) and dragon herbicides with the lowest levels on the second week (2.67 mg/dl). The sample contaminated with amino force herbicide had the least impact on glutathione levels (1.66 mg/dl) while the dragon herbicide depleted more of the glutathione levels (1.31 mg/dl). The Achatina achatina incubated with the soil sample spiked with vanish registered the highest catalase activity (6.2 1U/L) while action 40 recorded 3.9 IU/L as the least activity. Acetylcholineesterase activity seen in Achatina achatina incubated with soil sample 4(vanish) was inhibited beyond all other samples with 0.169 IU g protein-1 as the least value with the exception of amino force that  depreciated to 0.108 IU g protein-1on the third week. This study reveals how detrimental these herbicides can be to achatina achatina which counsels the farmers on their selectivity for agricultural purposes. Keywords: oxidative stress, acetylcholinesterase, herbicides, biomarkers, activity.