Abstract
Cyhalofop-butyl (CyB) is a widely used selective aryloxyphenoxypropionate (AOPPs) herbicide that is primarily applied in paddy fields to control barnyard grass. Despite its extensive use, concerns regarding its ecotoxicological effects on non-target invertebrate organisms, such as earthworm, remain largely unexplored. This study examined the chronic toxicity of CyB on Eisenia fetida within the soil. Over a period of 28 days exposure, various biochemical indicators, such as reactive oxygen species (ROS) and associated antioxidant enzymes (SOD, CAT, POD, GST, MDA), were assessed at different exposure concentrations (0-5.0 mg kg(-1)) of CyB. The results demonstrated that CyB exposure could induce significant oxidative stress in earthworms, leading to altered antioxidant enzyme activity and increased lipid peroxidation. Additionally, transcriptomic analysis revealed differential expression genes related to the oxidative stress response and detoxification mechanisms, suggesting potential metabolic disruptions in Eisenia fetida. These results would fill the gaps in the toxicity of CyB to earthworm and emphasize the need for further environmental risk assessments to ensure soil ecosystem sustainability.