Environmental impacts and social responses to genetically engineered crops

1. Environmental impacts and social responses to genetically engineered crops L. LaReesa Wolfenbarger University of Nebraska at Omaha

2. Potential benefits of transgenic organisms: environmental, health, social

3. Why so much potential? • Genetic engineering provides a greater range of possibilities for transferring desired traits into organisms.

4. The potential is biological novelty • Genetic engineering provides a greater range of possibilities for transferring desired traits into organisms. • A greater diversity of organisms may be modified • The quantity and quality of traits are limited by the identification of useful genes and are not constrained by existing variation among interbreeding relatives

5. Are they good or bad for the environment?

6. Yes, according to the plant biotechnology industry

7. No, according to environmental activist groups

8. Answer • Environmental impacts vary on a case by case basis • Environmental tradeoffs most likely • Values and not science determine whether outcome is good or bad

9. The role of science: what are the environmental consequences? x x L Effect on environment J Level of disturbance to environment

10. Social responses: what consequences are acceptable? x x L Effect on environment J Level of disturbance to environment

11. One point of agreement • Case-by-case environmental impacts

12. Overview • Possible environmental consequences • Environmental impacts of Bt corn and Round up Ready soybean • Social responses to these impacts • Predicting environmental impacts of future GE crops

13. Further degradation Improvement What are the possible environmental consequences of GE crops? No change

14. Using past experience to think of possible effects • Past experience with introductions of chemicals • Vary in toxicity, persistence • Lethal, Sublethal, No effect • Past introductions of species: intentional and unintentional • Unwanted spread of an organism or its genes

15. Chemicals and rat mortality

16. Persistence of chemicals varies

17. Using past experience to think of possible effects • Past experience with introductions of chemicals • Past introductions of species: intentional and unintentional

18. Intentional Landscaping Restoration/reintroductions Agricultural crops Biological control Unintentional Hitchhikers Past biological introductions

19. Possible outcomes of biological introductions Introduction of plants Survival or Death Reproduction or not Population dies out Self-sustaining population Spread and persistence Never really spreads

20. Kudzu spread and persists beyond its intended purpose

21. Can ecologists predict how species will spread • Can identify plants characteristics in common BUT • Lag times can occur. • Repeated introductions have different results. • Biological organisms can evolve.

22. Possible outcomes of biological introductions Pollen flows to wild relative Introduction of plant Hybrid formation or not Survival or Death Hybrid survival or death Reproduction Hybrid reproduction or not Self-sustaining population Self-sustaining hybrids Spread and persistence

23. Gene flow from crops to wild relatives is implicated in enhanced weediness in wild relatives of 7 of the world’s 13 most important crops. (Ellstrand, 1999)

24. Are current GE crops likely to spread? Self-sustaining populations Crop Outside of cultivation HT Oilseed rape Unlikely HT Corn Unlikely Bt and GNA Potato Unlikely HT Sugar beet Unlikely Crawley et al. 2001. Nature 409: 682-683.

25. Summary of possible environmental impacts • Improvements if less toxic and does not spread outside of cultivation • Degradation if more toxic or spreads uncontrollably

26. Less toxic to what?Spread where?

27. The environment: Biodiversity and interactions Bigger predators Predators Herbivores Plants

28. Ecological functions Bigger predators Predators Pollinators Herbivores Plants: primary producers Decomposers

29. Impacts on the environment occur through alterations of… • what species are present • how many individuals of each species • the ecological function(s) of a species in an ecosystem • the biological interactions affecting a species’ function in the environment

30. Humans are part of the environment • herbivores • predators • environmental engineers

31. Environments are a continuum Grassland environment Agricultural environment Forest environment

32. What general factors define the context? • The transgenic organism • Where it is introduced • environment • Baseline for comparison and evaluation • What GE crop will replace: regional agricultural practices

33. Presence of transgenic crop or its transgene plant above ground roots decomposing tissue pollen drift gene flow to wild relatives in natural ecosystem How a GE plant will interact with the environment

34. Changes in agricultural practices associated with adoption of a transgenic crop Pesticide use patterns Amount of agricultural land Tillage practices Crop diversity/rotation Other ways introducing a GE crop will affect the environment

35. Phytoremediation • Remove and sequester toxic heavy metals • Transform pollutants into less toxic forms

36. What do we know about environmental impacts of current GE crops?

37. Adoption of GE crops in U.S. Source: Biotechnology Industry Organization and USDA

38. Bt crops protect plants against specific insect pests

39. The story of Monarchs and Bt corn

40. We saw the findings as an illustration of how superficial risk assessment [for genetically modified foods] was...The question still remains, would this science have been done if the monarch wasn’t such a beautiful butterfly?” We saw an embargoed copy of a Cornell press release where we thought the risk seemed exaggerated,”

41. Components of risk assessment for monarch butterflies Monarch Occurrence and Distribution Behavior (oviposition preferences, phenology) • Monarch • Toxic effect • (lethal/sublethal) Environmental exposure Risk • Bt corn • Production and Distribution • Pollen characterization • Bt expression • Pollen shed (timing, duration, quantity) • Deposition and dispersal • Milkweed • Occurrence and Distribution • (Regional, landscape, habitat, abundance in corn) Adapted from Sears et al. 2001. PNAS 98: 11937-11942.

42. Monarch survival: 9 days after onset of pollen deposition • No differences among Bt and Non-Bt sweet corn treatments • Survival significantly decreased in presence of insecticide treatment Percent survival From Stanley-Horn et al. 2001. PNAS 98: 11931-11936

43. Studies with Bt corn underscore importance of context • Susceptibility of butterfly and moth species varies • Exposure varies geographically and locally • Susceptibility of lacewings (predatory insect) varies with prey species

44. Results of formal risk assessment • The six studies published in PNAS showed there was little risk to monarch larvae from the two most commonly grown types of Bt corn because the pollen isn’t toxic in the concentrations that monarch larvae would encounter in the fields.

45. Components of risk assessment for monarch butterflies Monarch Occurrence and Distribution Behavior (oviposition preferences, phenology) • Monarch • Toxic effect • (lethal/sublethal) Environmental exposure Risk • Bt corn • Production and Distribution • Pollen characterization • Bt expression • Pollen shed (timing, duration, quantity) • Deposition and dispersal • Milkweed • Occurrence and Distribution • (Regional, landscape, habitat, abundance in corn) Adapted from Sears et al. 2001. PNAS 98: 11937-11942.

46. “I felt that the conclusions made from a one year study that excluded anthers were premature,” Obrycki says. “That’s why we requested that EPA shorten the reauthorization period until we had data from subsequent studies.” the studies do not rule out very small effects, long-term or sublethal effects Responses to EPA’s decision

47. Epilogue • Concern about ingestion of other plant parts • Longer term studies occurring • Registration will expire in 2006

48. My response and questions • subtle effects seem likely • Should this change the registration? • no, minimize impacts on monarchs • What if a broader number of butterfly species are affected?

49. Reduced impacts from pesticides

50. Insecticide use in cotton Number of treatment/acres