Legacy effects of agricultural management on ground beetle (Coleoptera: Carabidae) communities

Annual crop agriculture in the Midwest, USA is intensive, requiring large areas of land and chemical inputs to derive high productivity from monocultures of corn, soybean, and wheat. Intensive agriculture is not sustainable given its negative impacts on biodiversity, soil loss, nutrient pollution, and climate. However, conservation-oriented agricultural management has the potential to improve local biodiversity while enhancing ecosystem services to maintain crop yield. Ground beetles (Coleoptera: Carabidae) are abundant generalist predators in row crops that feed on a variety of pests (insects, weed seeds) and serve as important indicators of biodiversity. As such, the study of ground beetle communities and their population trends are important for understanding the long-term effects of agricultural landscapes on arthropod biodiversity.

I collected information on the communities of ground beetles at the Kellogg Biological Station Long-term Ecological Research (LTER) main site in 2019 in two conservation-oriented treatments, termed Reduced Input and Biologically Based. I then compared the results of this study to a similar study 25 years prior to determine the potential effects of long-term agricultural management, or legacy effects. Overall, I found a shift in the locally dominant community of ground beetles to species tolerant to agricultural disturbance, and a higher prevalence of granivorous species. Importantly, I found a 6-fold decrease in the activity-density of the locally dominant community after 25 years. Multiple factors may contribute to this decline and shift, including agricultural disturbance and pesticide use, as well as landscape factors attributed to agricultural intensification and expansion.