Diversity of carabids (Coleoptera: Carabidae) within two Dutch cereal fields and their boundaries

In this paper, the diversity and species richness of carabid beetles (Coleoptera: Carabidae) is reported for the two fields of winter wheat and their boundaries. Active carabid beetles were recorded in Wageningen, the Netherlands, using pitfall traps during the spring and early summer, and overwintering carabids were sampled by the soil cores in winter of 2004. 75 carabid species in adult stage and 12 carabid taxa as larvae were found in the pitfall traps. In addition, 11 taxa were found in the soil cores. Rarefaction curves indicated that species richness was identical in both fields and that observed differences were due to higher activity-density of carabids in field 1. Both fields hosted identical assemblages, although species in field 2 were more evenly distributed among ranks. The pre-requisites for high diversity of carabids in the study fields are discussed and the causes for the differences in overwintering densities and activity-densities between fields are hypothesized.