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ARS Home » Southeast Area » Gainesville, Florida » Center for Medical, Agricultural and Veterinary Entomology » Insect Behavior and Biocontrol Research » Research » Publications at this Location » Publication #430792
Research Project: Improved Biologically-Based Methods for Management of Native and Invasive Crop Insect Pests

Location: Insect Behavior and Biocontrol Research

Title: Identification and characterization of two new markers for differentiating fall armyworm strains across the western hemisphere

Author
item Nagoshi, Rodney
item TESSNOW, ASHLEY - Orise Fellow
item Meagher Jr, Robert

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/23/2026
Publication Date: 6/2/2026
Citation: Nagoshi, R.N., Tessnow, A.E., Meagher Jr, R.L. 2026. Identification and characterization of two new markers for differentiating fall armyworm strains across the western hemisphere. PLOS ONE. https://doi.org/10.1371/journal.pone.0350388.
DOI: https://doi.org/10.1371/journal.pone.0350388

Interpretive Summary: The fall armyworm, Spodoptera frugiperda, is a major pest of corn and several other crops. Although native to the Western Hemisphere, established populations were detected in western Africa in 2016 and have since been found in most corn producing areas in the Eastern Hemisphere. Fall armyworms consist of two populations historically called “host strains”. Understanding the behavior of the host strains will significantly facilitate efforts to control this pest. Unfortunately, the genetic tools available are inadequate, consisting of a single genetic marker. This paper describes two new strain markers that provide new genetic tools for strain analysis. The data confirms earlier conclusions about how the strains differ in behavior and genetics while also expanding on these observations to describe how each strain is evolving. These markers will facilitate further studies on the population behavior of fall armyworm in the Western Hemisphere and should advance our understanding of the global movements of this important agricultural pest.

Technical Abstract: The fall armyworm (FAW) (Spodoptera frugiperda J.E. Smith) is a major pest of corn and several other crops. Although native to the Western Hemisphere, established populations were detected in western Africa in 2016 and have since been found in most corn producing areas in the Eastern Hemisphere. FAW consists of two populations historically called “host strains” that are believed to be undergoing sympatric speciation with reproductive isolation being driven primarily by host plant use. The C- and R-strains are morphologically indistinguishable and so can only be identified by a small set of molecular markers with polymorphisms in a single locus, the Triosephosphate isomerase gene (Tpi), considered the most reliable for population studies. This reliance on a single marker limits confidence in the accuracy of strain identification and the consequent extrapolations of strain characteristics. This paper describes two new strain markers that provide new genetic tools for strain analysis. The data confirms earlier conclusions about the primacy of the Z-chromosome in strain identity, the strain divergence of the Z-chromosome as a single genetic unit and expand upon previous observations to quantify differences in how each strain is evolving. These markers will facilitate further studies on the population behavior of FAW in the Western Hemisphere and should advance our understanding of the global movements of this important agricultural pest.