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ASSESSING POSSIBLE ECOLOGICAL RISKS OF GENETICALLY MODIFIED CROPS: GENE EXPRESSION ASSAYS AND GENETIC MONITORING OF NON-TARGET ORGANISMS
Blum, M, U Stolz, AND M J. Bagley. ASSESSING POSSIBLE ECOLOGICAL RISKS OF GENETICALLY MODIFIED CROPS: GENE EXPRESSION ASSAYS AND GENETIC MONITORING OF NON-TARGET ORGANISMS. Presented at Science Forum 2003, Washington, DC, May 5-7, 2003.
The objective of this task is to develop molecular indicators to evaluate the integrity and sustainability of aquatic fish, invertebrate, and plant communities (GPRA goal 4.5.2). Specifically, this subtask aims to evaluate methods for the measurement of:
fish and invertebrate community composition, especially for morphologically indistinct (cryptic) species
population genetic structure of aquatic indicator species and its relationship to landscape determinants of population structure (to aid in defining natural assessment units and to allow correlation of population substructure with regional stressor coverages)
genetic diversity within populations of aquatic indicator species, as an indicator of vulnerability to further exposure and as an indicator of cumulative exposure
patterns of temporal change in genetic diversity of aquatic indicator species, as a monitoring tool for establishing long-term population trends.
Widespread planting of genetically modified crops with the Bt transgene pesticide has led to concern over non-target effects of Bt compounds in agroecosystems. While some research suggests that non-target organisms exposed to Bt toxin exhibit reduced fecundity and increased mortality, other studies suggest that exposure has little or no effect on non-target organisms. The US EPA is therefore investing in research to better understand the potential risks that Bt crops may pose to non-target organisms. Indicator species will first be identified for non-target exposure monitoring in and around Bt-corn and Bt-cotton agroecosystems. Gene expression assays will subsequently be developed to assess exposure of non-target indicator organisms to Bt toxins. These assays will be employed to screen individuals for exposure to Bt toxins, while additional genetic monitoring will be done to establish population level responses to Bt exposure. Baseline studies of the population genetic structure of non-target indicator species inside and outside of areas planted with Bt crops will provide essential information on migration, genetic diversity, and effective population sizes. Further monitoring of indicator species over time will help establish whether localized Bt exposure influences the long-term viability of non-target populations. A combination of gene expression assays and population genetic monitoring will provide a comprehensive approach for evaluating how non-target Bt exposure may affect individual, population and ultimately, ecosystem health. Adapting this research to provide field monitoring tools will offer the U.S. E.P.A. Office of Pesticide Programs methods for tracking and mitigating potential non-target effects of Bt crops.