A TOXICITY TEST IN ARTIFICIAL SOIL BASED ON THE LIFE-HISTORY STRATEGYOF THE NEMATODE PLECTUS-ACUMINATUS

The ecological risk assessment of toxicants in soil requires reproduci ble and relevant test systems using a wide range of species. To supple ment present test methods from the Organisation of Economic Cooperatio n and Development (OECD) in artificial soil with earthworms and spring tails, a toxicity test in OECD artificial soil has been developed usin g the bacterivorous nematode Plectus acuminatus (Bastian, 1865) (Nemat oda; Plectidae). The juvenile to adult ratio was used as a test parame ter since previous life-cycle studies pointed out that fitness of P. a cuminatus was strongly determined by changes in both reproduction and juvenile survival. Optimal conditions for the performance of nematodes in OECD artificial soil were determined (pH(KCl) = 5.5, temperature = 20 degrees C, and a moisture content of 70% dry wt. artificial soil), and tests were conducted with cadmium, copper, and pentachlorophenol. After an exposure period pf 3 weeks the EC50 for cadmium was 321.0 +/ - 1.7 mg/kg dry wt., and the no-observed-effect concentration (NOEC) w as 32 mg/kg dry wt. The EC50 for pentachlorophenol was 47.9 +/- 1.2 mg /kg dry wt., and the NOEC was <10 mg/kg dry wt. For copper the EC50 wa s 162 +/- 0.2 mg/kg dry wt., and the NOEC was 32 mg/kg dry wt. It is c oncluded that the nematode rest may well supplement current soil test systems using earthworms and springtails.