Genetics and ecology of Spodoptera frugiperda in an interbreeding region

In the U.S., the fall armyworm, Spodoptera frugiperda (J. E. Smith) is reported to overwinter in south Florida and Texas. The Florida Panhandle, located at latitude 30-31, is a transition zone between temperate and subtropical climates, been a potential site for interbreeding of Texas and Florida migratory populations. No study has documented overwintering survival and seasonal occurrence of S. frugiperda in the Florida Panhandle. In this study, we conducted a year-round pheromone trapping in commercial fields of corn, peanut, and cotton, from spring 2017 to spring 2019 in Escambia, Santa Rosa, and Jackson counties, using a total of 40 delta Pherocon® VI traps (Trécé Incorporated). Trap liners were replaced every two weeks and Scentry PSU pheromone lures (Scentry Biological Inc.) were replaced every four weeks. The occurrence of S. frugiperda in different seasons was quantified to document seasonal flight. Carbon isotopic composition analysis of moth wings was performed to investigate feeding prevalence among C3 or C4 host plants. The seasonal prevalence of the rice or corn host strains was documented by analysis of the polymorphism in the cytochrome-c-oxidase (COI) and Triose phosphate isomerase (Tpi) genes. In addition, the haplotype method was used to elucidate the suspected origin of migrating populations (i.e. south Florida or Texas). This study improves our understanding of the population dynamic of S. frugiperda in the Florida Panhandle, and its implications for IPM and IRM of this species.