Locomotor activity and respiration rate of the ground beetle, Pterostichus oblongopunctatus (Coleoptera: Carabidae), exposed to elevated nickel concentration at different temperatures: novel application of Multispecies Freshwater Biomonitor.

The aim of the work was to study effects of suboptimal temperature on nickel toxicity under chronic exposure and to apply the Multispecies Freshwater Biomonitor (MFB) for the first time to soil organisms in order to link behavioral to physiological endpoints. Ground beetles Pterostichus oblongopunctatus were reared at 10 or 20 degrees C on control or Ni-contaminated (2500 mg Ni kg(-1)) food. After 64 days half of the Ni-exposed beetles were transferred to uncontaminated food (elimination phase). The remaining Ni-exposed beetles were left on the contaminated food to the end of the experiment (96 days). After completing the experiment, respiration rate and locomotor activity were measured in Ni-contaminated beetles (Ni), Ni-contaminated ones after elimination (E), and controls (C). Then, the beetles were analyzed for Ni body loads. The respiration rate, which was always measured at 20 degrees C for all experimental groups, was highest in Ni beetles reared at 10 degrees C and did not differ between groups C and E. Similarly, locomotor activity was highest in Ni beetles, and marginally significant temperature effect was found. The study indicated thus that exposure to elevated Ni concentrations increased the maintenance costs in P. oblongopunctatus and that rearing the beetles at suboptimal temperature increased the respiration rate even further. However, the effects observed in both respiration rate and locomotor activity were reversible after decontamination. The study demonstrated also the potential of MFB for assessing the behavior of soil-dwelling organism in environmental toxicology.