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THE EVOLUTION OF RESISTANCE TO PLANT INCORPORATED PROTECTANTS BY TARGETED INSECT PESTS
Citation:
Stolz, U, M Blum, AND M J. Bagley. THE EVOLUTION OF RESISTANCE TO PLANT INCORPORATED PROTECTANTS BY TARGETED INSECT PESTS. Presented at Science Forum 2003, Washington, DC, May 5-7, 2003.
Impact/Purpose:
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.
Description:
Genetically modified (GM) crops, also known as transgenic crops, offer potential economic, environmental, and human health benefits. Balanced against these potential benefits are several possible liabilities, one of which is environmental harm. The EPA must fulfill its mandate to assess the environmental risks of (GM) crops based on the best available information. However, there is limited information available to make meaningful decisions about long-term environmental risks of GM crops. It is important that the EPA continue to ascertain long-term ecological risks and identify the types of new data that are required for the most accurate risk assessment possible. One important long-term risk is adaptation by targeted pests to plant-incorporated protectants (PIPs) such as insecticidal Bt proteins. Bt crops provide direct economic benefits to farmers and may provide human health and environmental benefits by decreasing the use of toxic pesticides normally used to control pest outbreaks. Insect resistance evolution to Bt crops would eliminate the benefits of PIP-expressing GM crops and require the use of traditional pesticides to control insect pests. Therefore, one important goal of the EPA is to delay the onset of resistance evolution and prolong the efficacy of PIPs. Additional information is required to evaluate the assumptions of models used to develop the agency's required strategy for insect resistance management (i.e., high dose, structured refuge) for different species and traits. Also, molecular screening for PIP-resistance in populations would allow early warning of potential outbreaks of resistant pest populations. Predicting the likelihood and rate of adaptation (i.e., evolution of PIP resistance) by targeted pests depends on a number of factors which are complex and poorly understood for most species. We will first examine the population genetics of a pest species to determine the amount of migration between different pest locations/populations and the levels of genetic variation in the wild. This information will be used to improve models of pest adaptation by adding actual field data into the models. We will also design PCR assays for detecting resistance in the field and evaluate this approach as an early warning system for detecting the evolution of resistance by the target pest. These results will provide the EPA Office of Pesticide Programs and Regional Offices with critical biological field data regarding insect resistance management/monitoring and will further the ultimate goal of decreasing the likelihood of resistance evolution by insect pests.