Biological and metabolism responses of earthworm (Eisenia fetida) exposed to metribuzin.

Abstract

Metribuzin, a widely used triazine herbicide, has been extensively studied for its toxic effects on aquatic organisms, but its impact on soil organisms, particularly earthworms, remains insufficiently understood. This study investigates the ecological toxicity of metribuzin on Eisenia fetida, with emphasis on growth inhibition, oxidative stress and metabolic alterations. Earthworms were exposed to metribuzin at concentrations of 0, 5, 10 and 20 mg·kg-1 in artificial soil for a 28-day period. The results demonstrated that metribuzin exposure significantly inhibited earthworm growth, with the most pronounced effects observed at the highest concentration (20 mg·kg-1). The induction of oxidative stress by metribuzin was evidenced by elevated ROS levels and reduced activities of SOD, CAT, and POD. Furthermore, metribuzin exposure increased the levels of MDA and 8-OHdG, suggesting enhanced lipid peroxidation and DNA damage. IBRv2 analysis indicated a dose-dependent escalation of oxidative stress, identifying ROS and 8-OHdG as the most sensitive biomarkers. Metabolomic analysis revealed marked disruptions in metabolic pathways, particularly those associated with the amino acid metabolism, TCA cycle and glutathione metabolism. These findings suggest potential toxicological risks of metribuzin to soil ecosystems and underscore the importance of incorporating soil organisms into herbicide risk assessments.