Total antioxidative status and the activity of peroxidase and superoxide dismutase in the haemolymph of Lymnaea stagnalis (L.) naturally infected with digenean trematodes

Indicators in the antioxidative system of snails naturally infected with three species of trematodes (Plagiorchis elegans, Paryphostomum radiatum and Echinoparyphium aconiatum) were compared. The total antioxidative status (TAS) and activities of peroxidase (POX) and superoxide dismutase (SOD) in the haemolymph of sexually mature individuals of wild-caught Lymnaea stagnalis, maintained at 19 8 Ci n the laboratory, were tested. No significant differences were detected in TAS between P. radiatum snails uninfected and infected, with the exception of the 20th day. In the case of snails infected with P. elegans TAS was higher than in controls only at the beginning of the experiment, while in those infected with E. aconiatum it was always lower than in the control group. In all infected snails the activ- ity of POX was higher than in uninfected snails. The changes in activity of SOD in the infected snails differed depending on the species of trematodes. Among the tested host -parasite systems, the survival rate of snails infected with E. aconiatum was the lowest. We suggest that the TAS of snails can be used as an indicator of trematode virulence.