Comparing the utility of host and primary endosymbiont loci for predicting global invasive insect genetic structuring and migration patterns

Halyomorpha halys, commonly known as the Brown Marmorated Stinkbug, is a highly polyphagous invasive pest introduced from East Asia into North America and Europe. It harbors ‘ Candidatus Pantoea carbekii’, an obligately-associated, vertically-inherited gamma-proteobacterial mutualist. We evaluated the use of this symbiont as a proxy for measuring host diversity, distribution, and phylogeography. Despite the symbiont’s accelerated molecular evolution, the symbiont genome shows relatively lower genetic diversity and structuring compared to the host mitochondrial genome in both native and invaded ranges. Therefore, we conclude that P. carbekii is not as effective as the host mitochondria for determining recent host population history and migration.