- Home
- > About
- > Vignettes
- > Biocontrol Services
Diverse landscapes promote biocontrol services
The soybean aphid, an invasive insect pest, is the greatest threat to soybean production in the United States. It is consumed by a number of natural insect enemies that can provide control of its populations, resulting in increased crop yields and reduced pesticide use.
KBS LTER researchers have estimated the value of this natural biological control of the soybean aphid in four states (Iowa, Michigan, Minnesota, and Wisconsin). A report on this research published in the Proceedings of the National Academies of Science in 2008 showed insect predators suppress soybean aphid outbreaks saving soybean farmers an average of $13–79 dollars per acre per year in reduced pesticide use and averted yield loss. For the four states studied, this is at least a $239 million per year value for this biological pest control service in soybeans.
Researchers also found biological control was maximized when the surrounding landscape contained a diversity of crop and non-crop habitats within 1 mile of the focal soybean field. The presence of corn within 1 mile was negatively associated with biocontrol services. Corn is a less favorable habitat for many lady beetles—the predominant predator of soybean aphids—and other beneficial insects that feed on pests such as the soybean aphid. However, corn grain and stover are increasingly looked to as feedstocks for ethanol production. From 2006 to 2007, corn acreage increased by 19% in the United States, reducing landscape diversity in many areas. As farmers plant more corn—creating less diverse landscapes—the ability of that landscape to supply beneficial predators to control pests in soybeans and other crops is reduced, a loss valued at about $58 million per year in the four states studied.
Achieving the biofuel production levels mandated by Congress will take millions of acres to provide the necessary raw materials and will change agricultural landscapes. In developing policy regarding biofuels, it is important to consider the impact of landscape change on ecosystem services such as biocontrol. Increased corn prices and production may provide an immediate profitability benefit to corn farmers; however, many of these same farmers incur hidden costs because of the accompanying landscape change. For example, for farmers who grow only corn and soybeans, increasing corn acreage and reducing soybean acreage probably means higher costs for soybean pest control. These impacts extend to neighboring farmers and society as a whole through an overall reduction in biocontrol services from these landscapes.
These findings should help policymakers think about which and how much of any biofuel crop, as well as the location of the crop, makes sense for a particular landscape. Policy could either support monocultures of a single biofuel crop or, ideally, support diverse mixtures of many biomass sources, including perennial trees and grasses as well as corn. Diversifying landscapes with biofuel crops such as switchgrass and mixed prairie could result in greater biological control and pollination services, more wildlife habitat, and enhancement of other ecosystem services, including climate change mitigation and improved water quality.