Date of this Version The fall armyworm (FAW), Spodoptera
frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is an
economically important pest of maize, sorghum, cotton, and rice
in the Western Hemisphere. Previous studies on genetic diversity
of FAW focused on identification of the corn and rice host
strains; there is limited information about geographic genetic
variation. To bridge this gap, I investigated the genetic
diversity of FAW using representative samples from the United
States, Argentina, Panama, and Puerto Rico with amplified
fragment length polymorphism (AFLP). This study also
investigated the susceptibility of the Puerto Rico FAW
population to ten different insecticides used by Dow
AgroSciences (DAS) Research Station, Puerto Rico. Analysis of
molecular variance (AMOVA) using AFLP revealed that the majority
(71.2%) of the total variation is within FAW populations; only
28% of the variation was among populations. This indicates
significant gene flow for FAW throughout the Western Hemisphere.
Also,