Doris Fovwe Ogeleka, Duke Okoro, Onome Oghenefejiro Udubrae
In this study Tympanotonus fuscatus and Lumbricus Terrestris were exposed to Cotchlor® and Gobara®, a selective and non-selective commonly used herbicides in order to determine the toxicological and biochemical effects. The acute toxicity of Cotchlor® and Gobara® were determined using the Organization for Economic Development and Cooperation (OECD) #218 and 207 protocol respectively. Similarly, the anti-defensive mechanisms [superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)] as well as oxidant activity – lipid peroxidation indicated as malondialdehyde were used to assess the herbicides' harmful effects. The effective concentration (EC50) of Cotchlor® for periwinkle (Tympanotonus fuscatus) was 25 ± 1.44 mg/L while Gobara® was 250 ± 1.5 mg/L. Similarly, the EC50 for earthworm for Cotchlor® and Gobara® was 25 ± 1.55 mg/L and 50 ± 1.72 mg/L respectively. As the concentrations of exposure in Tympanotonus fuscatus increased, the antioxidant activity namely SOD, CAT and GPx decreased significantly at a level of PË‚0.05. The study concluded that the test herbicides produced reactive oxygen species (ROS) resulting in increasing levels of lipid peroxidation, which may have altered the activities of SOD, CAT and GPx causing oxidative stress in Tympanotonus fuscatus. Due to their hazardous potentials, the release of the test chemicals and other similar herbicides into the environment may result in a significant loss and biochemical alterations of the non-target test species - periwinkles and earthworms.
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