Issues surrounding GM foods:

1. Development of insecticide-resistant insects
In any group of organism that are given a poison (like bacteria and antibiotics), there are bound to be a few who somehow survive the poison due to a natural genetic variation. What happens when the ECB population develops resistance to Bt ???

EPA's Refuge strategy.

On October 16, 2001, the EPA announced that it had approved the use of Bt corn for another 7 years. However, As a condition of EPA's approval of the renewed registrations of Bt corn and cotton, EPA included numerous provisions :

• Additional field research on pest biology;
• Monitoring for the development of resistance or increased tolerance to the Bt protein;
• Grower education;
• Development of a remedial action plan in case resistance is identified;
• Increased communication among growers, producers, researchers, and the public; and an
• Insect Resistance Management (IRM) program.

From the EPA's Regulation of Biotechnology for Use in Pest Management:

• Farmers who plant Bacillus thuringiensis (Bt) corn are obligated to plant a 20% non-Bt corn refuge as part of an Insect Resistance Management (IRM) program.

IRM is the term used to describe practices aimed at reducing the potential for insect pests to become resistant to a pesticide.

• Bt IRM is of great importance ==> the threat insect resistance poses a big Question Mark on the future use of Bt plant-pesticides!.
• A structured High-Dose / refuge strategy is a non-Bt block or portion of a grower’s fields that provides for the production of susceptible insects that may randomly mate with resistant insects that may emerge from Bt fields and dilute resistance.
• The refuge supplies a source of moths that are not exposed to Bt corn to mate with those that have resistance to Bt, slowing the onset of resistance in corn borers.
• The High Dose refers to the lethal dose of Bt that is also necessary to kill off hybrid offspring with 1 resistance & 1 susceptable allele. Way cool!
• The size, placement, and management of the refuge is critical to the success of the high dose/structured refuge strategy. (The Economics of Within-Field Bt Corn Refuges)
• The EPA mandates specific IRM requirements for Bt crops under the Food, Fungicide, Insecticide and Rodenticide Act. "

The EPA requirement is 20% refuges in corn-growing areas and 50% in cotton areas. Refuges can be planted in blocks, as borders or in strips of multiple rows. see The Economics of Within-Field Bt Corn Refuges, AgBio Forum, 2000)

• A refuge should be planted within 1/4 mile of Bt corn. It is required within a half-mile.
  
• Spraying is an option in refuges, but no Bt sprays can be used.
  
  
• To protect nontarget insects, the EPA asks producers to place the refuge where possible between Bt corn and habitats, such as prairies, forests, conservation areas and roadsides.
  
  
• Both refuge and Bt blocks should be treated the same in terms of planting date, tillage and fertilization.
  
  
• Growers are required to mark their Bt fields to avoid confusion and to report to their seed salesman any sign that resistant borers exist in their Bt fields.
  
  
• Testing Bt refuge strategies in the field Fred Gould Nature Biotechnology 18, 266 - 267 (2000)
  
  
• Resistance to Bt toxin surprisingly absent from pests Jeffrey L Fox September 2003 Nature Biotechnology pp 958 - 959. Good news: ECB resistance to Bt is much slower that expected! "Defying the expectations of scientists monitoring transgenic crops, target insect pests have developed little or no resistance to Bt crops thus far, according to the USDA. These findings suggest that transgenic Bt crops could enjoy more extended, more profitable commercial life cycles and that the measures established to mitigate resistance before the crops were introduced are paying off."
  
  
• Things tend to get WICKED:
  • Insect resistance to Bt crops: evidence versus theory; Bruce E Tabashnik , Aaron J Gassmann , David W Crowder & Yves Carrière Nature Biotechnology Feb2008
    • Global monitoring of resistance of six major pests to the Bt toxins in transgenic crops indicated that in at least 1 species, Helicoverpa zea, "document the first case of field-evolved resistance to a Bt toxin produced by a transgenic crop"
  • No Field-evolved resistance to Bt toxins Oct 2008 Nature Biotechnology
    • "We emphatically disagree with the conclusions of Tabashnik et al. that the data published in these two articles demonstrate field-evolved resistance in H. zea for four reasons...

2. Non-target insect damage (The Dark Side of Bt) for background see EPAs regulation of Bt Crops

A chilling development for Bt crops: A Cornell University study (J.E. Losey et al., "Transgenic pollen harms monarch larvae," Nature, 399:214, 1999) found that Bt pollen was toxic to Monarch caterpillars in the laboratory. [Image] Since monarch caterpillars feed on milkweed, which often grows around corn fields, it was possible that our little non-target insect friends were being killed in high numbers around Bt corn fields.

 

HOWEVER, Losey's study was highly artificial - the caterpillars were kept in petri dishes, with only one thing to eat: leaves covered with lots of Bt pollen. They had to eat, or they were going to die - and the only thing they had to eat (Bt-covered leaves) WOULD make them die, because they are lepidopterans!

Nevertheless, the EPA started a major investigation of Bt crops.

Report: 9/20/00: Little Danger in Biotech Crops: "The US EPA issued a report stating that Bt crops that have been genetically engineered to kill insects pose 'no unreasonable adverse effects' to Monarch butterflies or to any other animal.

• Although pollen from GM corn can kill Monarchs in large doses, there is little risk to them around corn fields. Evidence indicates that the corn may even turn out to be beneficial to the butterflies because farmers are using less chemical pesticides, EPA said.
• In the study, the risk to butterflies ranges from low to very little depending on whether they are feeding inside or around the perimeter of corn fields.
• EPA also considered the impact of the crop on lady bugs, rodents and other animals.
• The crops provide significant benefits both to farmers and the environment, the study aid, estimating that direct benefits to farmers likely exceeded $100 million last year, the peak year for production of the crops. The study also affirmed that the crops approved for human consumption are safe to eat."

Several articles in 2001 aand 2002 confirmed this report Impact of Bt corn pollen on monarch butterfly populations: A risk assessment Mark K. Sears, Galen P. Dively, et al, PNAS October 9, 2001, 98: 11937-11942 [PDF] (Go to this paper in class)

 

 

3. Food safety, Food labeling, and Public Perception

• The FDA says that GM foods are safe. [Are GM Foods Safe? ]
• The EPA says that GM crops are safe [Are Bt crops safe?]
• The GAO says that GM foods are safe [Biotech Foods 'As Safe as Conventional Foods'] (In fact, they may be safer! They may be as Safe as Baby Shampoo!)
• The Society for Toxicology says that GM foods are safe [Toxicologists Label GM Foods Safe]

  Do people in the US think that GM food is safe? [ABC news poll says no]

• Do people know that they are eating GM foods everyday? [Most don't]
• Are there many GM foods on the market today? [Oh mais oui] Check out the Greenpeace True Foods list to see if your M'n'Ms are really GM'n'Ms and your daily Frosted Flakes are enhanced with more than just 10 vitamins and minerals!

Why isn't GM food LABELED AS SUCH? The Federal Food, Drug, and Cosmetic Act requires labeling - under section 201(n) - ONLY

1. "if a bioengineered food is significantly different from its traditional counterpart ..".
2. "if an issue exists for regarding how the food is used or consequences of its use from its traditional counterpart .."
3. "if a bioengineered food has a significantly different nutritional property from its traditional counterpart ..".
4. "if a new food includes an allergen that consumers would not expect to be present based on the name of the food.."

• Zambia rejects US GM grain: New York Times: August 29, 2002: "Almost 2.5 million Zambians are reportedly in danger of starvation, but the government is worried that the food might be a health risk. Zambia also fears that farmers may try to plant the biotech grains, contaminating the country's crops and possibly threatening exports to countries with restrictions on genetically modified crops."

4. Controlling the spread of transgenes:

• Will be be able to control where every GM seed or pollen grain ends up? [No]
  • Grass Created in Lab Is Found in the Wild Aug 2006 That's why they call it creeping bentgrass, I guess.
  • August 9, 2006: Escaped golf-course grass frees gene genie in the US: The first time a GM plant has escaped into the wild in the US, and it has managed to do so before securing USDA approval ...ouch!!!!
  • New York Times, Sept 30, 2004, The Travels of a Bioengineered Gene,
  • New York Times, Sept 26, 2004, Can Biotech Crops Be Good Neighbors? By Andrew Pollack
  • Scientific American, Sept 21, 2004, GM Pollen Spreads Much Farther Than Previously Thought
    
    
• Will we be able to prevent the cross-pollination of GM crops and wild relatives? [ No]
  • In fact, gene flow is standard whether or not the plants in question are transgenic:, "In a literature review of the world's 13 most important food crops, 12 of these crops naturally hybridize with wild relatives in some part of their agricultural distribution". Gene flow and introgression from domesticated plants into their wild relatives. Annu. Rev. Ecol. Syst. Vol. 30: 539-563 (1999)
    
    
• However, scientists have shown that another factor that governs whether these genes will spread widely throughout the wild population = fitness. Burke & Rieseberg. (Sept 5, 2003) Fitness effects of transgenic disease resistance in sunflowers. Science 300: 1250. (Rieseberg is an IU Biology Prof.) If the transgene confers a reproductive advantage (better seed set) to the plant that obtains it, it is more likely to spread. If not, well then why worry ...
• "It's time to move beyond all the hand-wringing about whether and how often transgenes are going to escape and start attacking the real root of the problem, which is what impact will specific transgenes have if they get out," Burke says.
  
  
• Would it be wise to use seed-sterilization Terminator Technology (or GURTs - Genetic Use Restriction Technologies OR Technology Protection System, TPS...) to control spread of genes or unauthorized replanting? [BIG TIME NO] Click here for a good explanation of the Cre/Lox system used in terminator seeds

Stories we don't need...

• Taco Shells (StarLink, Aventis) were pulled from the shelves in October 2000 because they contained a crystal protein cry gene (cry9) that had been tested and approved by the EPA as safe for cattle feed, but had not yet approved it for human consumption. Baaad mooove, Aventis....
• Prodigene (November 2002) allowed a few 'volunteer' corn plants that were being field tested for production of a pharmaceutical to germinate and grow in the following year's soybean field. As a precaution, thousands of pounds of soybean seeds were destroyed, and as a punishment (and for compensation to the soybean farmers) Prodigene payed a $3.2 M fine..
• RoundUp PRO (think Tiger Woods...and its tale of regulatory approval) = we will read this in class!

Objectives:

1. Bt and bugs: What is IRM? What is a refuge and why does the EPA require its use with Bt Corn and cotton? Are refuges working in practice?
2. Bt and Monarchs: What is the effect of Bt crops on Non-target insects? Compare the findings of the Losey et al Nature paper (now retracted) with the EPS's 2000 report and Sears et al. 2001 PNAS paper
3. Why isn't GM food labeled as such by the FDA? - Explain the reasons!
4. Explain the major findings of the developing discovery (8/06) of the escape of RoundUp Pro Creeping Bentgrass: Grass Created in Lab Is Found in the Wild . How does this finding relate to the StarLink Taco Shells, and the Prodigene story?
5. 10AgBioSafety2k6ans.html; 10agbioquestions2k5.html