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Bt Corn


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bacillus thuringiensis

bacillus thuringiensis

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  • 1. B.T. PHONE HOME Marquie, E., Moran, J., Riepl, E., & Schorling, J.
  • 2. 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.
  • 3. 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.
  • 4. 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.
  • 5.  
  • 6. 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.
  • 7. 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.
  • 8. Some Boring Pictures
  • 9. 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.
  • 10. 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.
  • 11. 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.
  • 12. 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.
  • 13. Managing the Evolution of Insect Resistance to Transgenic Plants Andow, D.A., & Alstad, D.N.
  • 14. 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
  • 15. More Populus
  • 16. 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.
    • Witkowski, J.F., et al. 2002. Bt Corn and European Corn Borer. 11/28/2006.