Assessment of ammonium hydroxide effect on Eisenia fetida (Savigny, 1826): acute toxicity and avoidance tests

In this study, acute toxicity and avoidance tests were conducted to assess the effect of ammonium hydroxide 'AH' on the brandling worm Eisenia fetida (Annelida: Lumbricidae). Adults' earthworms were exposed to an increasing concentration of AH (0.0001, 0.001, 0.01, 0.1, 1 and 10 mg.cm −2) for contact filter paper test and (0, 0.05, 0.1, 0.5, 1 and 5 mg.g 1 of soil) for soil and avoidance tests. Our results show that AH caused a high mortality rate and a decrease in biomass according to the increase of concentrations and exposure time, causing some physiological symptoms (bleeding and burns) and behavioural responses. The LC 50 calculated for contact filter paper test after 48 h was 1.01 mg.cm −2 and 1.05 mg.g −1 for soil test after 14th days. Moreover, the EC 50 obtained in avoidance test was 0.05 mg.g −1, this means that the earthworms were able to immediately detect low concentration of AH in soils, avoiding it.