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Marquie, E., Moran, J.,Marquie, E., Moran, J.,Riepl, E., & Schorling, J.Riepl, E., & Schorling, J.

Transgenic MaizeTransgenic Maize

• Transgenic maize is corn that has Transgenic maize is corn that has been genetically modified to have been genetically modified to have agriculturally desirable traits; e.g. agriculturally desirable traits; e.g. herbicide and pest resistance.herbicide and pest resistance.

• Some of the most popular types of Some of the most popular types of transgenic crops are transgenic crops are Roundup Roundup Ready Ready plants.plants.

Roundup ReadyRoundup Ready Plants Plants

• RoundupRoundup contains glyphosate, the contains glyphosate, theactive ingredient is isopropylamineactive ingredient is isopropylaminesalt which inhibits an enzyme involved salt which inhibits an enzyme involved in the synthesis of tryosine, tryptophan, in the synthesis of tryosine, tryptophan, and phenylalanine.and phenylalanine.

• Roundup ReadyRoundup Ready plants are produced by plants are produced by Monsanto and are toleralnt to Monsanto and are toleralnt to glyphosate.glyphosate.

• Types of Types of Roundup ReadyRoundup Ready plants include plants include corn, sorghum, cotton, soy, canola, and corn, sorghum, cotton, soy, canola, and alfalfa.alfalfa.

What Is What Is BtBt??

• BtBt stands for stands for BacillusBacillusthuringiensis.thuringiensis.

• BtBt is a soil-dwelling microorganism is a soil-dwelling microorganism which contains the which contains the BtBt toxin. toxin.

• BtBt Corn is genetically engineered Corn is genetically engineered to produce the a certain type of to produce the a certain type of protein which in turn becomes the protein which in turn becomes the BtBt toxin. toxin.

Why Why BtBt??

• Control costs of EuropeanControl costs of European

Corn Borers and yield lossCorn Borers and yield loss

combined exceed $1 billioncombined exceed $1 billion

annually.annually.• European Corn Borer damage can cause European Corn Borer damage can cause

up to 25 bushels of corn lost per acre.up to 25 bushels of corn lost per acre.• Texas, Nebraska, west Kansas, and east Texas, Nebraska, west Kansas, and east

Colorado aggressively manage their Colorado aggressively manage their crops against Corn Borers.crops against Corn Borers.

European Corn European Corn BorerBorer

• Ostrinia nubilalis firstidentified 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 How Does BtBt Work? Work?

• Creating Creating BtBt Corn is Corn is

accomplished throughaccomplished through

inserting a gene from inserting a gene from Bt.Bt.• This allows the plant to produce Cry This allows the plant to produce Cry

proteins all by itself.proteins all by itself.• When ingested by an insect, its own When ingested by an insect, its own

digestive enzymes activate the toxic digestive enzymes activate the toxic form of the crystal protein.form of the crystal protein.

• The digestive system of the insect The digestive system of the insect crystallizes and it starves to death.crystallizes and it starves to death.

Benefits Of Benefits Of BtBt Corn Corn

• Protection by Protection by BtBt corn is as corn is asgood, if not better, thangood, if not better, thanthat provided typicalthat provided typicalcommercial insecticides.commercial insecticides.

• Normal spray-on Normal spray-on BtBt insecticide is insecticide is subject to inconsistency due to subject to inconsistency due to degradation from UV radiation, degradation from UV radiation, heat, desiccation sensitivity, heat, desiccation sensitivity, incomplete coverage of fields, and incomplete coverage of fields, and a diminished effect on older larva.a diminished effect on older larva.

Drawbacks Of Drawbacks Of BtBt

• It can be nearly $14 more perIt can be nearly $14 more perbushel than normally grown corn.bushel than normally grown corn.

• Does not have an effect onDoes not have an effect onaphids, spider mites, blackaphids, spider mites, blackcutworm, western bean cutworm, cutworm, western bean cutworm, rootworms, wireworms, white grubs, rootworms, wireworms, white grubs, seedcorn maggots, and seedcorn seedcorn maggots, and seedcorn beetles.beetles.

• StarLink Bt CornStarLink Bt Corn was prohibited for was prohibited for human consumption by the federal human consumption by the federal government because of the possibility of government because of the possibility of allergic reactions.allergic reactions.

Effectiveness Of Bt CornEffectiveness 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 Managing the Evolution of Insect Resistance to Transgenic PlantsResistance to Transgenic Plants

Andow, D.A., & Alstad, D.N.Andow, D.A., & Alstad, D.N.

Populus

• X:X: Population size and Population size and population density of population density of ECB in the toxic unitECB in the toxic unit

• Y:Y: Population size of Population size of ECB in the nontoxic ECB in the nontoxic unitunit

• Y/G:Y/G: Nontoxic density Nontoxic density• P:P: Resistance allele Resistance allele

frequency in the toxic frequency in the toxic unitunit

• W:W: Resistance allele Resistance allele frequency in the frequency in the nontoxic unitnontoxic unit

More PopulusMore Populus

ReferencesReferences

• Alstad, D.N., et al. 1995. Managing the Evolution of Alstad, D.N., et al. 1995. Managing the Evolution of Insect Resistance to Transgenic Plants. Insect Resistance to Transgenic Plants. ScienceScience. 268: . 268: 1894-1896.1894-1896.

• Ives, A.R., et al. 1996. Evolution of Insect Resistance to Ives, A.R., et al. 1996. Evolution of Insect Resistance to Bacillus thuringiensisBacillus thuringiensis. . Science.Science. 273: 1412-1413. 273: 1412-1413.

• Goldberger, J., et al. 2005. Goldberger, J., et al. 2005. BtBt Corn Farer Compliance Corn Farer Compliance with Insect Resistance Management Requirements in with Insect Resistance Management Requirements in Minnesota and Wisconsin. Minnesota and Wisconsin. AgBioForumAgBioForum. 8(2): 151-160.. 8(2): 151-160.

• Gesell, S. 9/9/2006. European Corn Borer Fact Sheet. Gesell, S. 9/9/2006. European Corn Borer Fact Sheet. 11/28/2006. 11/28/2006. ento.psu.edu/extension/factsheets/european_corn_borerento.psu.edu/extension/factsheets/european_corn_borer.htm.htm

• Witkowski, J.F., et al. 2002. Witkowski, J.F., et al. 2002. BtBt Corn and European Corn Corn and European Corn Borer. 11/28/2006. Borer. 11/28/2006. extension.umn.edu/distribution/cropsystems/bc7055.htextension.umn.edu/distribution/cropsystems/bc7055.html#ch6ml#ch6