Avoidance behavior of Eisenia fetida in oxytetracycline- and heavy metal-contaminated soils

To determine the behavior of oxytetracycline (OTC) and heavy metals in soil, this study assessed the pollutant-induced avoidance behavior of earthworms (E. fetida) exposed to zinc (Zn2+), lead (Pb2+), and OTC in soil. The results showed a clear avoidance response within 48 h of exposure to the highest concentrations of pollutants. Moreover, E. fetida was shown to be more sensitive to Zn2+ than to Pb2+ and OTC. Compared with OTC alone, the net response of earthworms increased in the OTC-Zn2+ and OTC-Pb2+ combined treatments, indicating a synergistic effect. Moreover, the net response (NR) of the earthworms was higher for OTC-Zn2+ than it was for OTC-Pb2+, possibly reflecting the differences in essential characteristics of Zn and Pb.