Revisiting fall armyworm population movement in the United States and Canada

Authors: TESSNOW, ASHLEY - Texas A&M University; Nagoshi, Rodney; Meagher, Robert - Rob; FLEISCHER, SHELBY - Pennsylvania State University

Submitted to: Frontiers in Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/30/2023
Publication Date: 1/24/2023
Citation: Tessnow, A.E., Nagoshi, R.N., Meagher Jr, R.L., Fleischer, S.J. 2023. Revisiting fall armyworm population movement in the United States and Canada. Frontiers in Insect Science. 3:1104793. https://doi.org/10.3389/finsc.2023.1104793.
DOI: https://doi.org/10.3389/finsc.2023.1104793

Interpretive Summary: Fall armyworm is a migratory insect moth pest that annually invades the central and eastern United States from overwintering habitats in southern Texas and Florida. Migratory pathways are important for growers to learn so that they can be ready to make management choices. Previous research showed that the Texas populations moved north and then east towards the northeastern regions of the U.S., whereas the Florida populations maintained movement along the Atlantic seaboard. Scientists with Texas A&M University and Pennsylvania State University, in collaboration with scientists from USDA-ARS, Center for Medical, Agricultural and Veterinary Entomology in Gainesville, Florida, used new information to compare the geographic distribution of these patterns. We confirmed the general accuracy of previous modeling efforts, except for late in the season, where our results suggests a higher proportion of Texas populations invading the northeast, extending into eastern Canada. We show that substantial intermixing of the Texas and Florida moths routinely occurs north of South Carolina, however we found that the Appalachian Mountains influence geographic patterns of the Texas and Florida populations. Finally, we discuss how these results may limit gene flow between the Texas and Florida overwintering populations and limit the hereditary consequences of interbreeding between these populations.

Technical Abstract: Biophysical approaches validated against haplotype and trap catch patterns have modeled the migratory trajectory of fall armyworms at a semi-continental scale, from their natal origins in Texas or Florida through much of the United States east of the Rocky Mountains. Using an expanded dataset extending into Canada, we assess the consistency of haplotype patterns that relate overwintered origins of fall armyworm populations to hypothesized dispersal trajectories in North America and compare the geographic distribution of these patterns with previous model projections. We confirm the general accuracy of previous modeling efforts, except for late in the season where our data suggests a higher proportion of Texas populations invading the northeast, extending into eastern Canada. We delineate geographic limits to the range of both overwintering populations and show that substantial intermixing of the Texas and Florida migrants routinely occurs north of South Carolina. We discuss annual variation to these migratory trajectories and test the hypothesis that the Appalachian Mountains influence geographic patterns of haplotypes. We discuss how these results may limit gene flow between the Texas and Florida natal populations and limit the hereditary consequences of interbreeding between these populations.