The edge of agriculture: Crop configuration and pest suppression

In agricultural landscapes, predatory insects provide an essential ecosystem service -- valued at billions of dollars annually -- by suppressing pests that damage crops. A new study published in Agriculture, Ecosystems & Environment that includes data from the U.S. National Science Foundation-funded Kellogg Biological Station Long-Term Ecological Research site found that natural pest suppression gains a big boost when agricultural landscapes are patchy and include a high ratio of natural 'edge habitat' between fields.

Better understanding of how pest suppression works can help researchers and growers to maintain productive crop yields. Past studies have focused on the types of habitat patches surrounding crop fields, but sometimes those types don't tell the whole story. This study, which draws on Kellogg Biological Station LTER data along with data from Southern Wisconsin, focuses instead on the spatial arrangement of habitat patches.

The researchers found that pest suppression at Michigan sites was consistently higher in landscapes with smaller, patches that interlaced agricultural and non-agricultural habitats, or different crops. In addition, crop production at the Michigan sites benefited from a high edge-contrast between annual crops and surrounding habitat. Grasslands appeared to be particularly beneficial as habitats for natural pest enemies and most effective when they are directly adjacent to annual crops.

The type of configuration that provides optimal pest suppression varied depending on the crop or geographic region. At the Wisconsin sites, pest suppression increased in conjunction with large core areas of grasslands and smaller fields, a configuration that increased within-field biodiversity along with pest suppression.

The team concluded that, in many cases, the benefit of increased pest suppression leading to increased yields would make it worthwhile to reconfigure landscapes. By helping maximize biodiversity and ecosystem services, such research studies offer a win-win for both nature and economy, the scientists believe.

"This study reminds us that all ecosystems are intricately connected, regardless of their human footprint," says Doug Levey, a program director in NSF's Division of Environmental Biology. "The more we understand those connections, the more we can benefit and protect them."