Soil surface Coleoptera include both pests and potential biological control agents. Some beetle species typically considered foliar can be trapped on the soil surface. Coleoptera trappable on the ground form a potentially interacting community because of their shared habitat. We trapped Coleoptera on the soil within experimental plots to compare conventional (CT) and direct seed (DS) operations in a typical winter wheat/spring cereal/legume (pea) rotation for 2 years. In each year, 6 treatments were compared (3 crops x 2 tillage methods) with 4 replications. Replicate plots were 15.2 by 19.4 m. Our data include over 75 species and morphospecies, predominantly in the families Carabidae, Staphylinidae, Anthicidae, Chrysomelidae, and Coccinellidae. Among Carabidae, the most abundant species, Poecilus scitulus, was substantially and significantly more abundant in CT treatments, and this effect was most pronounced in peas. In contrast, Pterostichus melanarius tended to be more abundant in DS plots than in other treatments, with the strongest effect in cereals. In addition, the on-station data is compared to an on-farm arthropod study carried out in Latah and Nez Pierce counties during the summer of 2002. In this study, 4 treatments were compared (2 crops x 2 tillage) with 3 replicates. The dominant species found in the study and community structure are compared to that found on-station. The mechanisms producing these patterns and implications for community function have not been determined. Hypotheses will be discussed.
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