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 (Zn(2+)), lead (Pb(2+)), and OTC in soil. The results showed a clear avoidance response within 48h of exposure to the highest concentrations of pollutants. Moreover, E. fetida was shown to be more sensitive to Zn(2+) than to Pb(2+) and OTC. Compared with OTC alone, the net response of earthworms increased in the OTC-Zn(2+) and OTC-Pb(2+) combined treatments, indicating a synergistic effect. Moreover, the net response (NR) of the earthworms was higher for OTC-Zn(2+) than it was for OTC-Pb(2+), possibly reflecting the differences in essential characteristics of Zn and Pb.