PNAS recently published a really interesting paper that estimated what the cost was, in terms of ecosystem services, of planting all that corn for ethanol production. Basically, when you plant just one crop, you reduce the amount natural control of pest insects by beneficial insects.
I’ve mentioned corn and ethanol before here–the change in the US landscape is dramatic, and will continue, unless legislation is changed. We are threatened by what one writer calls “The Corn-Ethanol Juggernaut”–in order to meet Congressionally mandated production goals, we must plant more corn. 8 BILLION gallons of ethanol are to be in use by 2012. This paper quantifies some of what that will cost us. From the 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)……
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.”
So, more pesticides, less profit for the farmer. Not good. Is congress likely to repeal or change the ethanol mandate? Um. Probably not, alas.
Full Citation:
D. A. Landis, M. M. Gardiner, W. van der Werf, S. M. Swinton (2008). Increasing corn for biofuel production reduces biocontrol services in agricultural landscapes Proceedings of the National Academy of Sciences, 105 (51), 20552-20557 DOI: 10.1073/pnas.0804951106
Bug Gwen 
It’s nice to see papers like this moving towards quantifications of ecosystem services. Thanks for pointing it out. :-)
On a smaller scale per site but possibly close in ultimate cost is the benefit or potential service of biocontrol in ornamental gardens. In my experience letting landscapes be more diverse and allowing predator/parasite populations balance saves the property owner $$ in application fees. But I have not quantified it; this study did and that’s great.
wow! that’s alot of corn. My first thought was – “Why doesn’t Congress have to do the NEPA process on their new production requirements?!!” Surely there would be some serious environmental consequences of all that corn.