Simulation of generational migrations of fall armyworm, Spodoptera frugiperda, moths

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.  The northern limit of the winter-breeding region for North America extends to southern regions of Texas and Florida, but infestations are regularly reported as far north as Québec and Ontario provinces in Canada by the end of summer.  Recent fall armyworm haplotype profiles have characterized migratory pathways from the distinct winter-breeding regions in Texas and Florida, but knowledge is lacking on the atmospheric role in influencing the 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 that had originated from winter-breeding areas in southern Texas and southern Florida using the HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory) atmospheric dispersion model.  Model simulations identified overlapping immigrant populations in the Alabama-Georgia and Pennsylvania-Mid-Atlantic regions, and regions that predominately developed from single natal sources, which corroborate previous migration maps based on the distribution of fall armyworm haplotype profiles.  The results contribute to knowledge of fall armyworm population ecology on a continental scale, and will aid in the prediction and interpretation of inter-annual variability of insect migration patterns including those in response to climatic change and modified agronomic practices.