Ecotoxicological assessment of ammonium glufosinate using standardized earthworm bioassays

Abstract

With the increasing use of pesticides, particularly glufosinate ammonium (Finale®), and the herbicide-resistant weeds, specifically those resistant to glyphosate, alongside the development of transgenic crops tolerant to glufosinate ammonium, it has become crucial to better understand the effects of herbicides on terrestrial ecosystems. This study aimed to assess the ecotoxicological effects of glufosinate ammonium on earthworms (Eisenia andrei), with a focus on acute and chronic toxicity, as well as avoidance behavior. The tests were conducted under controlled laboratory conditions. The trials included five concentrations of glufosinate ammonium and an untreated control (acute: 0, 175, 340, 505, 670, and 835 mg ai kg−1; chronic and avoidance: 0.0, 3.3, 5.0, 6.7, 8.3, and 10.0 mg ai kg−1), with four replicates for the acute and chronic tests, and five replicates for the avoidance test. The results revealed significant impacts on the survival, biomass, reproduction, and avoidance behaviors of earthworms at certain concentrations. The LC50-14d was determined to be 611.68 mg ai kg−1, indicating moderate herbicide toxicity. The EC50 for reproductive effects at 56 days and avoidance behavior within 48 h were 4.49 mg ai kg−1 and 3.30 mg ai kg−1, respectively. Concentrations of 8.3 and 10 mg ai kg−1 triggered the highest escape responses. This study demonstrates that even sublethal levels of glufosinate ammonium can significantly impair the reproductive capacity and avoidance behavior of E. andrei.