Phylogeographic Diversity of the Winter Moths Operophtera brumata and O. bruceata (Lepidoptera: Geometridae) in Europe and North America

The European winter moth,Operophtera brumata (L.), an invasive forest defoliator, is undergoing a rapid range expansion in northeastern North America. The source of this invasion, and phylogeographic diversity throughout its native range, has not been explored. To do this, we used samples from a pheromone-baited trap survey of O. brumata collected across its native range in Europe, and invasive range inNorthAmerica.Traps inNorthAmericaalsoattract acongeneric species, the Bruce spanwormO. bruceata (Hulst), and thewestern Bruce spanwormO. b. occidentalis (Hulst). From this sampling, we sequenced two regions of the cytochrome c oxidase subunit I mitochondrial gene; one region corresponds to theDNA ÔbarcodeÕ region, the other is a nonoverlapping section.We used these sequences, in combination with sequence data from a recent survey of the Geometridae in western North America, for phylogenetic and phylogeographic analyses to characterize genetic divergence and variation for O. brumata in North America and Europe, and O. bruceata and O. b. occidentalis in North America. We found O. brumata mtDNA diversity to be dominated by a single widespread, and common haplotype. In contrast, O. bruceata shows high haplotype diversity that is evenly distributed throughout North America. Phylogeographic patterns indicate an introduction of O. brumata in British Columbia likely originated from Germany, and suggest the invasive population in northeastern North America may have its origins in the United Kingdom, and/or Germany. We found uncorrected pairwise sequence divergence between Operophtera species to be 7%. O. b. occidentalis is 5% divergent from O. bruceata, has a restricted range in the PaciÞc Northwest, and has unique morphological characters. Together these lines of evidence suggestO. b. occidentalismay be deserving of species status. Additionally, a single morphologically unique Operophtera specimen, similar toO. bruceata, was collected in southern Arizona, far outside the known range ofO. bruceata. This suggests that North America may contain further, unsampled, Operophtera diversity.