BT Corn Bacillus thuringiesisa

1. BT CornBacillus thuringiesisa Better Technology Or Beyond Trust

2. Outline • What is Bt Crops / Bt Corn • Different Kinds of Bt Corn • Food Securities • Environmental Impacts • Soil Micro Organisms • Conclusion

3. What is Bacillus thuringiensis? • It is an aerobic, motile, gram positive, endospore forming bacillus bacteria. • It is a relative to the anthrax bacteria that is used for biochemical weapons. • It produces a parasporal crystal during stationary phase of its growth cycle. • This crystal control insect species of Lepidoptera, Diptera and Coleopetera that had worm or caterpillar stage in their life cycle.

4. Creating Genetically Modified Corn Brown Kathryn. Seeds of Concern. Scientific American. April 2001, page 52 - 57

5. What are Bt Crystals? • These crystal proteins are toxic to very specific species of insects yet harmless to humans and other beneficial insects. • There are about 150 insects that are known to be susceptible in a form or other to Bt toxin. • The crystal proteins bind specifically to certain receptors in the insect’s intestine. • Human and other vertabrates do not have these receptors in our bodies, so toxin is unable to affect us.

6. Cry Protein Toxin • There are three domains in this delta endotoxin. • Domain I and Domain II are very conservative. • Domain III is highly variable to attach to different receptors. • There are over 200 known variants for this cry or cryt protein • Common variants application to agriculture are: Cry1Ab, Cry1Ac, Cry1F, Cry3Bb, Cry2Ab that target to different insects and their larvae.

7. Currently Registered Plant Incorporated Protectants: • Monsanto’s have Bt corn YieldGard (MON810) Cry1Ab and BT GollGard Cotton (531) Cry 1Ac that represents about 85% of the Bt crops worldwide. • They are used to control European corn borer, for cotton bollworm, and tobacco budworm. • In 2003, EPA had approved the commericialization of corn with Cry3Bb gene for the control of corn rootworm (Diabrotica).

8. Why do we need Genetic Modified Crops? • According to United Nations Food and Agriculture Organization, there were 842 million people that we undernourished. • 10 million of those are living in the industrialized countries including United States. • The world population is expected to increase by 2.6 billion during the next 40 years. • The world gain production will need to increase 55 % over today’s level in order to meet the world food demand in the next quarter of century. • Where do we find enough arable land? How much fertilizer can be added in order to boost the yield? How much pesticides, herbicides, and other chemicals needed to protect our crops? • One way to increase the yield is to protect our crops by maintaining the potential yield at a high level. • IPM

9. The Challenge • The root exudates trans gene products in the rhizosphere • Tillage can mix these trans gene products throughout the soil. • Symbiotic micro organisms living in the soil can be affected, including earthworms, nematodes, other protozoa, bacteria, and fungi. • Nutrients cycling may be affected, nitrogen fixation, decomposition of foliage. • Microbial diversity may be affected. • Horizontal gene transfer into soil and genetic material uptake by other organisms, including other bacteria and protozoa. • Although there are extensive study of Bt crops’ environmental impact above ground, it is extremely difficult to study the organisms underground since there are a lot of confounding factors affecting the composition of soil and the micro organisms living in it.

10. The Major Findings from Experiments: • Crop decomposition, plant roots exudates, and sloughed and damaged root cells can release the transgenic products, and toxins into the soil. • Free DNA plasmid sequence can be released into the soil, bound to clays and accumulated. • The bound toxin to the clay and acid fraction can persisted in soil for more than 234 days which is the longest and end of the observational periods of the experiments conducted. • Rhizosphere micro organisms can benefit plants by suppressing or competing with pathogens. • Legumes required nitrogen fixing bacteria to grow in the nodules of the plants and interestingly, most of the corn farmers prefer to rotate the crops production with soybeans.

11. Keystone Paper: Effect of Cry3Bb Transgenic Corn and Tefluthrin on the Soil Microbial Community: Biomass, Activity and Diversity By: H.H. Devare, C.M. Jones, and J.E. Thies

12. Key Findings: • Neither Bt corn nor the application of insecticide had any significant effect on microbial biomass. • There was no significant effect of Bt corn or insecticide on Nitrogen mineralization potential • Neither Bt crops nor insecticide tefluthrin affected the short term nitrification rate. • Insecticide appeared to depress microbial respiration in rhizoshpere soil, but there is no difference in soil respiration activity between Bt and non Bt plots.

13. Effects of corn rootworm resistant transgenic corn engineered to express Bt toxin and tefluthrin on microbial biomass C, Nitrogen mineralization potential and short term nitrification rate in rhizosphere and bulk soil sampled from field trails Devare, M.H., Jones, C.M., and Thies, J.E. Effect of Cry3Bb Transgenic Corn and Tefluthrin on the Soil Microbial Community: Biomass, Activity, and Diversity. Journal of Environmental Quality. 33: 837 – 843, 2004

14. Effect of corn rootworm resistant transgenic corn engineered to express Bt toxin and the insecticide tefluthrin (I) on microbial respiration in bulk (open symbols) and rhizosphere (closed symbols) soil sampled from field trials. Devare, M.H., Jones, C.M., and Thies, J.E. Effect of Cry3Bb Transgenic Corn and Tefluthrin on the Soil Microbial Community: Biomass, Activity, and Diversity. Journal of Environmental Quality. 33: 837 – 843, 2004

15. Discussion • Minor alternations in the diversity of the microbial community could affect soil health and ecosystem functioning. • Plant variety may have an impact on the dynamics of the rhizoshpere microbial populations and in turn plant growth and health that could affect the ecosystem sustainability.

16. Future Prospectus • Although, the experiment did not show any significant effects on the microbial biomass, micro organisms activities or bacterial community structure, further study with longer term investigations are necessary to understand the impact of the endotoxin and the genetic materials effects on the soil microbial communities.

17. Integrated Pest ManagementIPM • IPM is the coordinated use of pest and environmental information with available pest control methods to prevent uncontrollable levels of pest damage by most economical means and with least possible hazard to people, property, and the environment. • It is a series of pest management evaluations, decisions and controls. • There are four tiered approach: Set Action Thresholds, Monitor and Identify Pests, Prevention and Control • Some simple practices include trapping devices, natural predators, insect growth regulators, mating disruption substances pheromones. • For home use example: adult lady beetles and their larvae are an excellent non chemical way control aphids, beetles and other larvae.

18. Conclusion • Neither risks nor benefits of transgenic crops are certain or universal. • There are limits in our capacity to make acceptable prediction on how our ecosystem works and how it in turns affects ourselves. • There are always additional or unpredictable or unidentified risks that we may not notice or understand. • We need to think outside of the paradigm that we had learned and bear an open minded scheme in providing solutions to the food security crisis and at the same time in protecting our fragile environment.