Community response to transgenic plant release: using mathematical theory to predict effects of transgenic plants

Authors


  • D. A. Andow is an insect ecologist with general interests in sustainable agriculture and conservation biology. He has served as a consultant to the US-EPA on ecological issues related to release of genetically engineered organisms into the environment and has served on the USDA-ABRAC (Agricultural Biotechnology Research Advisory Committee) since 1989. Research topics include biological control of arthropod and weed pests, conservation of rare arthropod species and beneficial arthropod natural enemies, and the ecology of invasions of arthropods.

219 Hodson Hall, Department of Entomology, University of Minnesota, St. Paul, MN 55108, USA. Fax 612 625 5299.

Abstract

Predicting the potential effects of introductions of plants on the structure of plant communities has been elusive. I suggest that mathematical models of resource competition might be useful for identifying categories of plants that either are unlikely to alter community structure or that have the potential for altering community structure. Assuming that the transgenic plant will escape and establish viable populations in nontarget habitats, this theory suggests that species that have a high minimum resource requirement are unlikely to alter community structure. The theory is elaborated to evaluate the potential effects on community structure of transgenic plants with resistance to primary consumers. Results indicate that the greatest reduction in the minimum resource requirement caused by resistance will occur when consumers are consuming enough plant biomass that the plant can no longer grow. If resistance to such a consumer were incorporated into a plant, it could lower the minimum resource requirement sufficiently that a transgenic plant would be able to alter community structure substantially. Examples of introductions of exotic plants, plant pathogens, and insect herbivores are given to support the conceptual basis of the theory. Not all transgenic plants with resistance, however, have the potential to alter community structure. Resistance to primary consumers that strongly reduce the biomass producing ability of a plant will probably be able to alter community structure, whereas resistance that reduces most other types of yield loss is less likely to alter community structure. The theory should be elaborated to incorporate more-realistic assumptions, such as those regarding reproduction, dormancy, and dispersal of the transgenic plants, and provide more detailed characterization of the potential hazard of transgenic plants to plant communities.

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