Diabrotica virgifera virgifera or western corn rootworm is a serious threat to corn farming causing widespread destruction to the roots of plants from feeding larvae. Transgenic strains of corn were developed to leverage toxin producing genes from Bacillus thuringiensis (Bt) as an insecticide.
Bt delta endotoxin has been in use since the 1960’s as a direct application insecticide and saw it’s first large-scale deployments as a transgenic GMO in 2003. By 2010, over 143 million acres (58 million hectares) were planted in the United States. Bt corn posses Bt delta endotoxin in varying concentrations throughout the plant body. When an insect comes into contact with Bt delta endotoxin the protein bonds with internal organs (gut) causing a structural breakdown there by releasing bacteria into the bloodstream causing septicemia and death.
The promise of Bt corn among other things is a reduction to the level of insecticide required during growing seasons which in turn modify the cost and operating expenditures of agribusinesses across the United States. Many health and environmental advocates target insecticide use as a major problem and a reduction in use may be seen as a welcome change in the corn industry’s methodology.
Proper management of Bt corn planting is essential in ensuring that this resource remains a viable deterrent to the western corn rootworm and other pests for as long a period of time as possible. A high-dose/refuge method for maintaining the efficacy of Bt corn involves setting aside ‘refuge’ plantings of non-Bt corn preventing selective pressure from building, keeping genetic populations dilute in terms of resistance. The high-dose/refuge practice which was highly effective until the 1990’s saw a dramatic loss of efficacy.
Recent investigations have shown that fields infested with Bt-resistant strains of D. virgifera virgifera were associated with insufficient or non-compliant refuge plantings of non-Bt corn. Recent surveys throughout the Midwest have estimated that merely 50-70% of farming operations are compliant.
More emphasis on proper management of Bt corn is needed to ensure that this advanced bioinsecticide realizes it’s full potential not only for business concerns but to also ensure that agribusiness is able to keep pace with an exploding global population in the decades to come. It is hard to ignore the fact that the campaign against the western rootworm is simply one of many battles fought waged by agriculture in the modern age and discipline and strict adherence to proscribed polices for management
Reference & Citations:
- James C (2010) Global Status of Commercialized Biotech/GM Crops: 2010. ISAAA Brief No. 42. Ithaca, New York: ISAAA.
- Bt Corn: Health and the Environment
- Journal of Animal and Feed Sciences, 2002. Vol.11, pages 1-18
Environmental Benefits of Genetically Modified Crops: Global and European Perspectives on Their Ability to Reduce Pesticide Use
- Adaptation and invasiveness of western corn rootworm: intensifying research on a worsening pest.
- AgBioForum: The Journal of Agrobiotechnology Management and Economics
- Ag Biosafety, University of Nebraska, Lincoln
- R. J. Wright, T. E. Hunt, J. F. Witkowski, B. D. Siegfried, and J. E. Foster. 2000. Choosing a Bt Transgenic Corn Hybrid. Nebraska Cooperative Extension NF00-409
- Agricultural Biotechnology, The Pew Charitable Trusts. This site hosts information developed through 2007 by the The Pew Initiative on Food and Biotechnology.
- GM Crop Database. Center for Environmental Risk Assessment (CERA)
- Information Systems for Biotechnology (ISB): A National Resource for Agbiotech Information, Virginia Tech.
- Regulating Biopesticides, United States Environmental Protection Agency
- The International Service for the Acquisition of Agribiotech Applications
- USDA, National Agricultural Library, Biotechnology information page.