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Oral: Dispersal at Multiple Scales: A Key to Outbreak of Disease Epidemics


Simulation modeling and mitigation of climate change effects on generational migrations of a crop pest: Fall armyworm (Spodoptera frugiperda).
J. WESTBROOK (1), R. Nagoshi (2), R. Meagher (2), S. Fleischer (3), S. Jairam (4) (1) USDA-ARS, U.S.A.; (2) USDA-ARS, U.S.A.; (3) Pennsylvania State University, U.S.A.; (4) Self-employed, U.S.A.

The fall armyworm (Spodoptera frugiperda) is a pest of tropical origin that cannot survive extended periods of freezing temperature, but must migrate northward each spring if it is to re-infest cropping areas in temperate regions. Genetic analyses have characterized northward migratory pathways from distinct winter-breeding regions in Texas and Florida, but knowledge is lacking on atmospheric influences on timing, distance, direction, and intensity of migratory flights. We estimated daily growth of corn plants and fall armyworm populations, and simulated generational migration of fall armyworm populations using the HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory) atmospheric dispersion model. Model simulations identified regions of overlapping immigrant populations from Texas and Florida and of populations that predominately developed from single natal sources. Reducing migrating populations in overwintering areas and successive immigration zones (known as stepping-stone nurseries) will help lower the pest status of this insect. One areawide management strategy being tested replaces a traditional ground cover plant species that is a good larval host with one that is a poor host plant. The results contribute to knowledge of fall armyworm population ecology on a continental scale, and will aid in the prediction, interpretation, and mitigation of insect migration influenced by climatic change and modified agronomic practices.