Assessing the potential for fall armyworm exchanges between the two American continents across the Mexico-Central America land bridge

Authors: Nagoshi, Rodney; MALO, EDI - El Colegio De La Frontera Sur (ECOSUR); CRUZ-ESTEBAN, SAMUEL - El Colegio De La Frontera Sur (ECOSUR); ROSAS-GARCIA, NINFA - Instituto Politécnico Nacional, Centro De Desarrollo De Productos Bioticos (CEPROBI); HERRERA-MAYORGA, VERONICA - Universidad Autónoma De Guerrero; Meagher Jr, Robert

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/7/2024
Publication Date: 3/3/2025
Citation: Nagoshi, R.N., Malo, E.A., Cruz-Esteban, S., Rosas-Garcia, N.M., Herrera-Mayorga, V., Meagher Jr, R.L. 2025. Assessing the potential for fall armyworm exchanges between the two American continents across the Mexico-Central America land bridge. PLOS ONE. 20(3).Article Number e0308501. https://doi.org/10.1371/journal.pone.0308501.
DOI: https://doi.org/10.1371/journal.pone.0308501

Interpretive Summary: Invasive pest insects are a growing problem as climate change and urbanization destabilize ecosystems and international trade facilitates the introduction of species into new locations. A related concern is gene flow between geographically distant populations that allows the rapid dispersion of deleterious traits across the host range. In both cases a defining factor is pest mobility, with species capable of long-distance flight and transient expansion even into regions that only support viability for a portion of the year being particularly problematic. The noctuid moth Spodoptera frugiperda, commonly known as fall armyworm, falls within this category. Although a semi-tropical species incapable of surviving periods of prolonged freezing temperatures, fall armyworm infestations are found in most locations capable of corn production, even in those with severe winters. A growing concern is how quickly deleterious traits (such as pesticide resistance) that arise in these populations in South America can reach populations in North America. One likely conduit is through the Central America land bridge. ARS scientists at CMAVE in Gainesville, FL collaborated with researchers in Mexico to test the likelihood of fall armyworm movements across Mexico. The results indicate that the exchange of these moths between the two American continents through Central America and Mexico is limited and does not involve migratory movements of large populations as observed in the United States.

Technical Abstract: The fall armyworm (FAW) is a major agricultural pest of corn and multiple other crops. A native of the Western Hemisphere it is now a global concern after its discovery in Africa in 2016 and subsequent infestations in Asia and Australia. A defining characteristic of FAW is its capacity for long distance migration, first documented for populations in North America and assumed to occur elsewhere. This study examines the extent to which the Mexico-Central America land bridge serves as a pathway for gene flow between the FAW from the two American continents. The work builds on previous surveys in Mexico that suggest possible geographical or meteorological barriers limiting mass population movements. In this study, additional collections from Mexico were analyzed for patterns of genetic variation and these were correlated with modeling of climate suitability, the locations of major corn production, and wind-dependent dispersal projections. The results were used to assess the frequency and magnitude of interactions between FAW from Texas, which is the migratory source for infestations in central North America, and those from Mexico. The data identify environmental factors influencing FAW dispersion patterns that impact the likelihood of genetic exchanges between dispersed populations across the Mexico-Central America corridor.