Characterization of a unique genetic strain of gypsy moth (Lymantria dispar) across the landscape of northern Minnesota

The European gypsy moth (Lymantria dispar dispar) was introduced into North America in 1869. This polyphagous pest is native to Eurasia, and consists of three subspecies which vary in female flight capability and breadth of host plants. Due to the higher invasive potential of flight capable females, the USDA has designated “Asian gypsy moths” as any gypsy moths with flight capable females. Morphological characters can differentiate between subspecies, but may be difficult to apply. As a result, molecular markers have been developed to identify the origin of suspect moths. One such marker is a nuclear marker designated as FS1. The Slow the Spread Program (STS) is the national program to for gypsy moth management in the United States. Annually, subsamples of moths from the STS program undergo molecular analysis. Gypsy moth populations in the Arrowhead region of Minnesota consistently exhibit a higher frequency of FS1- A alleles than other North American populations. However, Minnesota populations of gypsy moths do not have flight capable females. Higher FS1-A frequencies may suggest multiple introductions, which could be consistent with the prevalence movement pathways in this region. The Arrowhead region of Minnesota has extensive natural resources which are tourism destinations, additionally two international shipping ports are present in this region. In 2013 and 2014, dedicated trapping transects were established and monitored weekly to investigate questions surrounding the spatial and temporal dynamics of FS1-A frequencies in Minnesota. Moths collected in these trapping transects underwent molecular analysis and were used to investigate the distribution of FS1-A frequencies in relation to population characteristics and putative movement pathways.