The combined pollution of imidacloprid and glufosinate-ammonium aggravates toxicity on Hydrilla verticillata and epiphytic microbial community

The combined effects of imidacloprid (ICD) and glufosinate-ammonium (GLAM) on submerged plants and epiphytic microbial community remains unclear, despite the frequent co-occurrence of these pesticides in aquatic environments. In this study, a 24-day experiment was conducted to examine changes in water quality, plant physiology, and epiphytic microbial communities in Hydrilla verticillate -dominated wetlands under ICD alone or together with GLAM. Results showed that GLAM+ICD induced greater oxidative stress and a stronger antioxidant response in H. verticillata compared ICD alone, demonstrating that the mixtures exacerbated ecotoxicological effects on plant. Compared to ICD, many micro-biomarkers were obtained in ICD+GLAM, including Bacteroidota, Comamonadaceae, Proteobacteria and Cocconeis . Redundancy analysis indicated that the ICD concentration was correlated positively to Stigeoclonium, Closterium and Cocconeis , but negatively related with Oedogonium and Chloromonas , GLAM is opposite to ICD. More complex interkingdom interactions among bacteria and eukaryotes were observed in high concentration MIX treatment group compared to others. Co-occurrence networks analysis further demonstrated that GLAM and ICD changed microbial interactions within epiphytic biofilm, and impaired the stability and function of the microbial communities . These results underscore that the combined presence of ICD and GLAM poses a significant ecological risk to Hydrilla verticillate- biofilm system in agricultural regions.