Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 1, 2007
Publication Date: June 1, 2007
Citation: Nagoshi, R.N., Silvie, P., Meagher Jr, R.L. 2007. Comparison of haplotype frequencies can differentiate fall armyworm (Lepidoptera:Noctuidae) corn-strain populations from Florida and Brazil. Journal of Economic Entomology. 100(3):954-961. Interpretive Summary: Fall armyworm is an important agricultural pest of a number of crops in the western hemisphere. Two identical strains of fall armyworm exist that differ in plant host usage and habitat distribution. Of these, the corn-strain is the primary pest of corn and inflicts substantial economic losses on this crop in both North and South America. Scientists at the Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL, in collaboration with CIRAD, Brazil, describe molecular methods that can distinguish corn-strain populations in Florida from those in Brazil. This will allow investigations into the level of interactions between these two geographically distant populations and provide insight into the long-range movements of this pest. Furthermore, the molecular markers allow an examination of the genetic diversity within the corn-strain population that could identify subgroups that target different plant hosts. A better understanding of fall armyworm populations and their movement is critical for the development of strategies to control this economically important pest in both Brazil and the United States.
Technical Abstract: Fall armyworm is a major economic pest throughout the Western Hemisphere. Populations can be subdivided into two morphologically identical but genetically distinct strains (corn-strain and rice-strain) that differ in their host plant preferences. These can be distinguished by using polymorphisms in the mitochondrial Cytochrome oxidase I gene. Additional sequence analysis of this locus identified two sites that were highly polymorphic in the corn-strain population and that produced four different haplotype classes. Comparisons of the frequency distribution of these haplotypes found no seasonal or plant host specificities, but did demonstrate that the Brazil corn-strain population is different from corn-strain fall armyworm found in Florida. The development of a rapid means of distinguishing fall armyworm populations originating from Brazil versus Florida provides an opportunity for investigating and comparing the genetic complexity and long-range movements of this important agricultural pest.