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Bt Corn

Bt Corn



bacillus thuringiensis

bacillus thuringiensis



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    Bt Corn Bt Corn Presentation Transcript

    • B.T. PHONE HOME Marquie, E., Moran, J., Riepl, E., & Schorling, J.
    • Transgenic Maize
      • Transgenic maize is corn that has been genetically modified to have agriculturally desirable traits; e.g. herbicide and pest resistance.
      • Some of the most popular types of transgenic crops are Roundup Ready plants.
    • Roundup Ready Plants
      • Roundup contains glyphosate, the
      • active ingredient is isopropylamine
      • salt which inhibits an enzyme involved in the synthesis of tryosine, tryptophan, and phenylalanine.
      • Roundup Ready plants are produced by Monsanto and are toleralnt to glyphosate.
      • Types of Roundup Ready plants include corn, sorghum, cotton, soy, canola, and alfalfa.
    • What Is Bt ?
      • Bt stands for Bacillus
      • thuringiensis.
      • Bt is a soil-dwelling microorganism which contains the Bt toxin.
      • Bt Corn is genetically engineered to produce the a certain type of protein which in turn becomes the Bt toxin.
    • Why Bt ?
      • Control costs of European
      • Corn Borers and yield loss
      • combined exceed $1 billion
      • annually.
      • European Corn Borer damage can cause up to 25 bushels of corn lost per acre.
      • Texas, Nebraska, west Kansas, and east Colorado aggressively manage their crops against Corn Borers.
    • European Corn Borer
      • Ostrinia nubilalis first
      • identified in Boston in 1917.
      • Introduced from Hungary and Italy by way of broom corn plants.
      • Feeds on over 250 different kinds of plants.
      • First generation bores into the stalk and causes the plant to fall over.
      • Second generation bores into the tassles and causes the ears to fall out.
    • Some Boring Pictures
    • How Does Bt Work?
      • Creating Bt Corn is
      • accomplished through
      • inserting a gene from Bt.
      • This allows the plant to produce Cry proteins all by itself.
      • When ingested by an insect, its own digestive enzymes activate the toxic form of the crystal protein.
      • The digestive system of the insect crystallizes and it starves to death.
    • Benefits Of Bt Corn
      • Protection by Bt corn is as
      • good, if not better, than
      • that provided typical
      • commercial insecticides.
      • Normal spray-on Bt insecticide is subject to inconsistency due to degradation from UV radiation, heat, desiccation sensitivity, incomplete coverage of fields, and a diminished effect on older larva.
    • Drawbacks Of Bt
      • It can be nearly $14 more per
      • bushel than normally grown corn.
      • Does not have an effect on
      • aphids, spider mites, black
      • cutworm, western bean cutworm, rootworms, wireworms, white grubs, seedcorn maggots, and seedcorn beetles.
      • StarLink Bt Corn was prohibited for human consumption by the federal government because of the possibility of allergic reactions.
    • Effectiveness Of Bt Corn
      • Spray-on Bt insecticide controls roughly 60-95% of the first generation and 40-80% of the second generation.
      • Bt Corn species control more than 99% of the first generation.
    • Managing the Evolution of Insect Resistance to Transgenic Plants Andow, D.A., & Alstad, D.N.
    • Populus
      • X: Population size and population density of ECB in the toxic unit
      • Y: Population size of ECB in the nontoxic unit
      • Y/G: Nontoxic density
      • P: Resistance allele frequency in the toxic unit
      • W: Resistance allele frequency in the nontoxic unit
    • More Populus
    • References
      • Alstad, D.N., et al. 1995. Managing the Evolution of Insect Resistance to Transgenic Plants. Science . 268: 1894-1896.
      • Ives, A.R., et al. 1996. Evolution of Insect Resistance to Bacillus thuringiensis . Science. 273: 1412-1413.
      • Goldberger, J., et al. 2005. Bt Corn Farer Compliance with Insect Resistance Management Requirements in Minnesota and Wisconsin. AgBioForum . 8(2): 151-160.
      • Gesell, S. 9/9/2006. European Corn Borer Fact Sheet. 11/28/2006. ento.psu.edu/extension/factsheets/european_corn_borer.htm
      • Witkowski, J.F., et al. 2002. Bt Corn and European Corn Borer. 11/28/2006. extension.umn.edu/distribution/cropsystems/bc7055.html#ch6