ECOLOGY AND POPULATION BIOLOGY Identification and Comparison of Fall Armyworm (Lepidoptera: Noctuidae) Host Strains in Brazil, Texas, and Florida

Fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a major economic pest throughout the Western Hemisphere. Studies of populations in the southern United States and the Caribbean demonstrated the existence of two morphologically identical but genetically distinct host strains. These races can be distinguished by using polymorphisms in the mitochondrial cytochrome oxidase I gene that deÞne two distinct maternal lineages that correlate with strain-speciÞc behaviors in Florida populations. Although there is evidence of different biotypes in Brazil, it has not been demonstrated that these biotypes are equivalent to the U.S. strains. Sampling from Brazil indicates that its fall armyworm populations consist of the two strain-speciÞc haplotypes found in Florida and also display the expected biases in plant host distribution. The same genetic markers also were present in samples fromTexas, a major source of migrating fall armyworm inNorth America. These results indicate that the biology and behaviors of Brazilian fall armywormpopulations are similar to those found in North America.