Bt Corn


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bacillus thuringiensis

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Bt Corn

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