Proceedings of the National Academy of Sciences of the USA article on Biofuels and Biological Control Services

Landis, D.A., M.M. Gardiner, W. van der Werf, and S.M. Swinton. 2008. Increasing corn for biofuel production reduces biocontrol services in agricultural landscapes. PNAS. PNAS published online before print December 15, 2008, doi:10.1073/pnas.0804951106. View article.

1.  Natural predators cut pesticide use and boost farm profits

• Predators suppress soybean aphid outbreaks saving soybean farmers in four Midwestern states an average of $13–79 dollars per acre per year in reduced pesticide use and yield losses
• The value of this biological control service is due to both reduced pesticide use and increase crop yields.
• Lower values are for those farmers who already actively manage aphid populations with Integrated Pest Management (IPM) practices.
• Higher values are for those farmers who rely more exclusively on biological control e.g. some organic farmers.
• Previous studies show lady beetles are the predominant predators
• The presence of natural enemies reduced the need for pesticide applications.
• In 2005 (a high aphid year) 100% of fields studied reached aphid thresholds (i.e. required sprays) in the absence of natural enemies, and 75% in the presence of natural enemies.
• In 2006 (a low aphid year), 62% of fields reached aphid thresholds in the absence of natural enemies, but none did in the presence of natural enemies.
• We estimate a minimum benefit of soybean aphid biocontrol of $239 million per year across the four states we studied (using the IPM scenario).
• The 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.

2. More corn acreage to produce biofuels reduces the value of natural pest control

• In 2007 corn production increased to record levels in part due to the demand for corn grain to produce ethanol
• While corn acreage declined in 2008, it was still the second highest on record.
• Increased corn reduces biocontrol services in soybean by $58 million per year over the four state region.
• This likely occurs because corn supports fewer soybean aphid predators than other habitat types.

3. Growing a variety of biofuel crops can enhance landscape diversity and ecosystem services

• Biofuel crops including switchgrass and mixed prairie have the potential to diversify landscapes and enhance biodiversity.
• This could result in
• Increased biological control services
• Increased pollination services
• More wildlife habitat
• In developing policy regarding biofuels it is important to consider the impact of landscape change on ecosystem services.