Response types in Collembola towards copper in the microenvironment.

Laboratory studies were carried out to cast light on differences in density responses among collembolan species to copper (Cu)-polluted environments. In a recolonisation experiment, mesofauna originating from a copper (Cupolluted arable field were allowed to colonise defaunated Cu-contaminated and uncontaminated soil cores for 3 months. The abundances of Pseudosinella alba and gamasid mites were higher in the uncontaminated soil, whereas the majority of other collembolans tended to be more abundant in the Cu-enriched soil. Behavioural experiments were conducted to test the ability of single Collembola species to distinguish between filter paper and food soaked in water, Cu, and calcium (Ca) solutions. Onychiurus armatus avoided both Cu and Ca, whereas Folsomia quadrioculata and Folsomia manolachei showed a significant preference for Cu. Isotomurus palustris was not able to distinguish between Cu and water. The results are compared and discussed with regard to other studies on the occurrence and behaviour of Collembola in Cu-contaminated environments. We suggest that microsite selection according to preference or avoidance of high salinity of pore water may partly explain the community structure of Collembola in Cu-polluted soils which are characterised by an increase of euedaphic species. More studies have to be carried out to generalise this concept and to explore to what extent reduced predation by gamasid mites contribute to the success of certain Collembola in Cu-contaminated sites.