The document discusses transgenic maize (corn) that has been genetically modified to be resistant to herbicides and pests. It focuses on Bt corn, which contains a gene from Bacillus thuringiensis that produces a toxin lethal to the European corn borer. Bt corn provides effective control of this pest with little to no impact on other insects. While Bt corn reduces yield losses and costs of control, there are concerns about the evolution of pest resistance over time.

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.

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. 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