More Corn = $58 Million in Lost Ecosystem Services, More Aphids, Fewer Ladybugs

ladybug photo

photo: jhoc via flickr

Because the US encouraged increased planting of corn by 19% in 2006 and 2007 the number of insect pests that plague the soybean crop increased as well, causing lost yield to farmers or forcing them to apply more insecticide to deal with the problem. The pest in question is the soybean aphid and the cause of its increase is declines in ladybug populations. Here's how this is happening:
Though New Scientist frames it in the context of increased support for biofuels, it's just as much a further example of the problems of mono-crop agriculture in general, rather than biofuel crops specifically.

Lower Crop Diversity Means Lower Insect Diversity
When you lower crop diversity you also lower the diversity of the types on insects inhabiting the landscape. How this applies to the rise of soybean aphid and the decline of the ladybug was detailed by researchers at Michigan State University, who found that "the more the local landscape was dominated by maize, the less impact natural predators had on soybean aphids." As corn does not support large populations of aphids, it also tends to not have large amounts of that insect's natural predator, the ladybug.

Lower Crops Yields & More Insecticide
The researchers found,

...that just in four states—Michigan, Iowa, Minnesota and Wisconsin—the increased maize plantings of 2007 cost farmers $58 million in lost biological services from aphid-munching bugs, and reduced normal biological control services for aphids by 24%.

via: New Scientist
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