Ground beetle (Coleoptera: Carabidae) abundance and diversity in five Wisconsin agroecosystem trials

Ground beetles were sampled from five agroecosytem trials in southern Wisconsin as a satellite project of the Wisconsin Integrated Cropping System Trials.  Pitfall traps were placed in four replications of continuous corn, two organic corn systems, and pasture, as well as three replications of prairie restoration plots.  Traps were placed for one week sampling periods three times during the summer of 2012 and will be repeated in 2013.  Contrary to our hypothesis that decreases in both physical and chemical disturbances will yield an increase in ground beetle abundance and diversity, fewer numbers and species of carabids were collected from the pasture and prairie plots than from the three corn treatments.  Comparing 2012 samples to those collected from the same plots in 1995-96 revealed that the abundance of the two most common species, Pterostichus melanarius and Bembidion quadrimaculatum oppositum, was temporally reversed.  Pterostichus melanarius was 7.4 times more prevalent in 1995-1996 while B. oppositum was 4.8 times less abundant than in 2012.  A canonical variates analysis (CVA) comparing data collected from the current sampling period to results from 1995-96 should provide insights into the impact of time as well as the effect of disturbance associated with the cropping systems and pasture/prairie treatments on ground beetle abundance and diversity.