Do geographical distance and host plant species affect the population genetic structure of the carrot weevil (Listronotus oregonensis) in North America?

Population genetic studies of insect pests enhance our ability to understand and anticipate problems in agroecosystems, such as pest outbreaks, insecticide resistance, or expansions of the host range. This study focuses on geographic distance and host plant selection as potential determinants of genetic differentiation of the carrot weevil, Listronotus oregonensis, a major pest of several apiaceous crops in North America. We used both haplotype discrimination with mitochondrial DNA and genome scan using a genotyping-by-sequencing approach to characterize the genetic population structure of the carrot weevil. A total of 220 individuals were sampled from 17 localities in the provinces of Québec, Ontario, Nova Scotia (Canada) and in the state of Ohio (USA). Our results showed significant genetic differences between distant populations across North America, indicating that geographic distance represents a significant factor of differentiation for the carrot weevil. In contrast, we found no evidence of population structure associated to the four apiaceous crops tested (carrot, parsley, celery and celeriac). This first characterization of the genetic structure of the carrot weevil contributes to a better understanding of the gene flow of the species and helps to adapt local pest management measures to better control this agricultural pest.