Antioxidant enzyme activities of Folsomia candida and avoidance of soil metal contamination.

Induction of the antioxidant enzymes catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) and the avoidance of potentially toxic metals in soil by Folsomia candida were investigated. Both laboratory-spiked and field-polluted agricultural soils were used. Cadmium (Cd) concentrations in body tissues, animal avoidance behaviour and physico-chemical properties of the field soils were also determined. In laboratory Cd-spiked soils, the CAT and SOD activities in the Cd treatments were 71.1-94.7 and 1.31-4.55 times higher than in the control, respectively. In field-polluted agricultural soils, the CAT and POD activities generally increased with increasing pollution index (PI Nemerow ) of soil Cd, Cu, Pb and Zn. The CAT, POD and SOD activities at different PI Nemerow were 65.7-128, 30.1-180 and 36.5-95.8% higher than in the control, respectively. In line with the enzyme activities, Cd concentrations in the animal bodies were 8.31-15.1 and 3.21-10.0 times higher than in the control in spiked and field-polluted soils, respectively. Avoidance behaviour also increased with increasing metal concentrations in both soils. The effects of metals on CAT, POD or SOD activity were influenced by soil properties such as soil texture and pH. These results indicate that the antioxidant enzymes activities of F. candida can be induced by heavy metals and potentially used to assess the toxicity, and also that soil properties must be considered in the analysis of enzyme activities in different types of field soils.