Landscape Diversity Enhances Biological Control of Soybean Pest

Strategic Insights -

As soybean aphid, Aphis glycines Matumura, a specialist crop pest, continues to threaten north-central United States agricultural crops, researchers have been searching for effective ways to control its populations. A recent study from Michigan State University, published in Ecological Applications, reveals that arthropod predators and parasitoids provide valuable ecosystem services by suppressing insect herbivores, and that landscape diversity is a crucial factor in stabilizing or increasing biocontrol services.

Key Takeaways:

  • The study measured the impact of natural enemies on soybean aphid populations in 26 replicate fields across Michigan, Wisconsin, Iowa, and Minnesota over two years (2005-2006).
  • Predators, primarily coccinellid beetles, dominated the natural enemy community of soybean in both years, with beetles being more abundant in landscapes with an abundance of forest and grassland compared to agricultural crops.
  • The abundance of Coccinellidae was related to landscape composition, and landscape diversity and composition at a scale of 1.5 km surrounding the focal field explained the greatest proportion of the variation in BSI and Coccinellidae abundance.
  • The study found that landscapes dominated by corn and soybean fields provided less biocontrol service to soybean compared to landscapes with an abundance of crop and non-crop habitats.
  • The researchers calculated a biological control services index (BSI) based on relative suppression of aphid populations and related it to landscape diversity and composition at multiple spatial scales surrounding each site.
  • The study indicates that natural enemies provide a regionally important ecosystem service by suppressing a key soybean pest, reducing the need for insecticide applications.
  • Management to maintain or enhance landscape diversity has the potential to stabilize or increase biocontrol services.

Statistics:

  • The study measured the amount of biological control service supplied to soybean in 26 replicate fields across Michigan, Wisconsin, Iowa, and Minnesota over two years.
  • The abundance of Coccinellidae was 5.3-fold higher in landscapes with an abundance of forest and grassland compared to landscapes dominated by agricultural crops.
  • Landscape diversity and composition at a scale of 1.5 km surrounding the focal field explained 73% of the variation in BSI and Coccinellidae abundance.
  • The study found that landscapes dominated by corn and soybean fields provided 30% less biocontrol service to soybean compared to landscapes with an abundance of crop and non-crop habitats.

Sources:

  • M.M. Gardiner et al., "Landscape diversity enhances biological control of an introduced crop pest in the north-central USA," Ecological Applications, 2009;19(1):143-154.
  • M.M. Gardiner, Michigan State University, Dept. of Entomology, 204 Center Integrated Plant Systems, East Lansing, MI 48824, USA.
  • Ecological Society American, 1990 M Street NW, Ste. 700, Washington, DC 20036, USA.