Examining the genetic diversity of the orange blossom wheat midge, Sitodiplosis mosellana (Géhin), across North America

The orange blossom wheat midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae), is a significant pest of wheat (Triticum spp.) grown in the Northern Hemisphere. It was accidently introduced to North America over 200 years ago and has subsequently spread throughout the northern Great Plains. Since 2010, several Canadian spring wheat varieties containing the resistance gene Sm1 have been released. Due to the potential of wheat midge populations to evolve virulent biotypes to Sm1, cultivars containing Sm1 are grown with a susceptible cultivar in an interspersed refuge. An understanding of the genetic diversity of wheat midge populations could provide important information on the potential development of resistance to Sm1. In the current study, we used two mitochondrial genes (CO1 and ND4) from wheat midge collected across the northern Great Plains and Québec in North America to assess population structure and genetic diversity. We found limited genetic diversity and population structure across the sampled North American populations. We also assessed North American haplotype similarity to wheat midge collected from Europe and China and found high similarity between North American and European populations, although sampling in Europe was limited. This supports the hypothesis that North American populations originated from Europe.