The genetic characterization of fall armyworm populations in Ecuador and its implications to migration and pest management in the northern regions of South America.

Authors: Nagoshi, Rodney; CANARTE, ERNESTO - National Institute For Agricultural Research (INIAP); NAVARRETE, BERNARDO - National Institute For Agricultural Research (INIAP); PICO, JIMMY - National Institute For Agricultural Research (INIAP); BRAVO, CATALINA - National Institute For Agricultural Research (INIAP); ARIAS DE LOPEZ, MYRIAM - Non ARS Employee; GARCES-CARRERA, SANDRA - National Institute For Agricultural Research (INIAP)

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/20/2020
Publication Date: 8/3/2020
Citation: Nagoshi, R.N., Canarte, E., Navarrete, B., Pico, J., Bravo, C., Arias De Lopez, M., Garces-Carrera, S. 2020. The genetic characterization of fall armyworm populations in Ecuador and its implications to migration and pest management in the northern regions of South America. PLoS One. 15(8):e0236759. https://doi.org/10.1371/journal.pone.0236759.
DOI: https://doi.org/10.1371/journal.pone.0236759

Interpretive Summary: The fall armyworm (Spodoptera frugiperda) is a moth pest native to the Western Hemisphere that has recently become a global problem, invading Africa and much of Asia. The species has a broad host range, long-distance migration capability, and a propensity for the generation of pesticide resistance traits that make it a formidable invasive threat and a difficult pest to control. While fall armyworm migration has been extensively studied in North America, where annual migrations of thousands of kilometers are the norm, migration patterns in South America are less understood. As a first step to address this issue we have been genetically characterizing fall armyworm populations in Ecuador, a country in the northern portion of South America that has not been extensively surveyed for this pest. These studies confirm and extend past findings indicating similarities in the fall armyworm populations from Ecuador, Trinidad-Tobago, Peru, and Bolivia that suggest substantial migratory interactions. Specifically, we found that populations throughout Ecuador are genetically homogeneous and quantify using an intron sequence the level of similarity between fall armyworm from different locations in South America, which has implications for how migration might be occurring. In addition, we unexpectedly found these observations only apply to one subset of fall armyworm (the C-strain), as the other group (R-strain) was not present in Ecuador. The results suggest differences in migration behavior between fall armyworm groups in South America that appear to be related to differences in host plant preferences.

Technical Abstract: The fall armyworm (Spodoptera frugiperda) is a moth pest native to the Western Hemisphere that has recently become a global problem, invading Africa and much of Asia. The species has a broad host range, long-distance migration capability, and a propensity for the generation of pesticide resistance traits that make it a formidable invasive threat and a difficult pest to control. While fall armyworm migration has been extensively studied in North America, where annual migrations of thousands of kilometers are the norm, migration patterns in South America are less understood. As a first step to address this issue we have been genetically characterizing fall armyworm populations in Ecuador, a country in the northern portion of South America that has not been extensively surveyed for this pest. These studies confirm and extend past findings indicating similarities in the fall armyworm populations from Ecuador, Trinidad-Tobago, Peru, and Bolivia that suggest substantial migratory interactions. Specifically, we found that populations throughout Ecuador are genetically homogeneous and quantify using an intron sequence the level of similarity between fall armyworm from different locations in South America, which has implications for how migration might be occurring. In addition, we unexpectedly found these observations only apply to one subset of fall armyworm (the C-strain), as the other group (R-strain) was not present in Ecuador. The results suggest differences in migration behavior between fall armyworm groups in South America that appear to be related to differences in host plant preferences.