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Source: Wageningen University

Large amounts of maize stimulate aphid plague

To become less dependent on oil imports, the American government plans to blend ten percent of bio-ethanol in petrol. Government funding for the bio-ethanol production has led to a sharp increase in US maize cultivation over recent years, with a 19 percent growth in maize acreage in 2007 alone. A field study by Michigan State University and Wageningen University showed that increases in the maize cultivation acreage can have a negative influence on natural plague suppression in other crops. Growing large amounts of maize for bio-ethanol is not a sustainable option is the conclusion published by the scientists in the Proceedings of the National Academy of Sciences (23/12/2008).

The article was co-written by Wopke van der Werf of the Crop and Weed Ecology science group.

With a field study in four states, the scientists show that there is a reduction in natural plague suppression in soy beans in areas with a large amount of maize than in those with less maize crops. Ladybirds limit the aphid population in landscapes with diverse land use. Over the past decade aphids have become a major problem for soy farms.

Increasing corn for biofuel production reduces biocontrol services in agricultural landscapes
Douglas A. Landisa, Mary M. Gardinera, Wopke van der Werfb, and Scott M. Swintonc
Edited by May R. Berenbaum, University of Illinois, Urbana, IL, and approved November 5, 2008 (received for review May 22, 2008)
Proceedings of the National Academy of Sciences of the United States

Abstract

Increased demand for corn grain as an ethanol feedstock is altering U.S. agricultural landscapes and the ecosystem services they provide. From 2006 to 2007, corn acreage increased 19% nationally, resulting in reduced crop diversity in many areas. Biological control of insects is an ecosystem service that is strongly influenced by local landscape structure. Here, we estimate the value of natural biological control of the soybean aphid, a major pest in agricultural landscapes, and the economic impacts of reduced biocontrol caused by increased corn production in 4 U.S. states (Iowa, Michigan, Minnesota, and Wisconsin). For producers who use an integrated pest management strategy including insecticides as needed, natural suppression of soybean aphid in soybean is worth an average of $33 ha−1. At 2007–2008 prices these services are worth at least $239 million y−1 in these 4 states. Recent biofuel-driven growth in corn planting results in lower landscape diversity, altering the supply of aphid natural enemies to soybean fields and reducing biocontrol services by 24%. This loss of biocontrol services cost soybean producers in these states an estimated $58 million y−1 in reduced yield and increased pesticide use. For producers who rely solely on biological control, the value of lost services is much greater. These findings from a single pest in 1 crop suggest that the value of biocontrol services to the U.S. economy may be underestimated. Furthermore, we suggest that development of cellulosic ethanol production processes that use a variety of feedstocks could foster increased diversity in agricultural landscapes and enhance arthropod-mediated ecosystem services.

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