Toxicity of glufosinate-ammonium in soil to earthworm (Eisenia fetida)

Purpose Glufosinate-ammonium (GLA) is commonly used in tropical agriculture. The frequency and dosage of GLA applications far exceeded the recommended amounts, causing a substantial portion to leach into the soil, becoming a pseudo-persistent pollutant. The earthworm (Eisenia fetida) is a critical bio-indicator of soil health. The effects of pesticides on earthworms are significant to analyzing pesticides' harm to the soil. Therefore, it is urgent to study the toxicity of GLA to earthworms. Materials and methods The artificial soil method was adopted to test the toxicity of GLA on earthworms from the aspects of acute toxicity, growth, reproductive toxicity, the activity of antioxidant and detoxification enzymes, and DNA damage. Results GLA exhibited low toxicity (LC50 > 2000 mg/kg) to earthworms in 7-day and 14-day soil tests. But at the individual level, exposure to GLA could decrease the earthworms' weight, cocoons, and larvae, even under low-concentration stress. The effect of GLA on the individual level of earthworm may be due to the impact on the microscopic level, so the enzyme activity and DNA damage were determined. At the protein level, exposure to GLA could change the activity of superoxide dismutase (SOD), catalase (CAT), glutathione s-transferase (GST), guaiacol peroxidase (POD), and acetylcholine esterase (AChE) of earthworms. Furthermore, at the molecular level, the comet assay suggests that the olive tail moment (OTM) increased dramatically under the GLA treatments. Conclusions The results will be helpful for further understanding the negative influence of GLA on the earthworm and provide a foundation for the rational use of GLA and eco-environmental risks of soil pesticide contamination.