Population genomics of red sunflower seed weevil, Smicronyx fulvus

Smicronyx fulvus is pest of cultivated sunflowers that is typically controlled byaerial applications of insecticides. In recent years, increased damage to sunflower cropsin South Dakota has raised concerns that the weevil may be evolving resistance topyrethroids. Almost nothing is known about the dispersal capabilities and populationgenetic structure of this insect, making it impossible to predict how insecticideresistance alleles might spread through the larger population.We assembled a low-coverage draft assembly of the S. fulvus genome and used this asa reference to map short-read sequencing data from pooled weevil population samplescollected along a transect from North Dakota to Colorado. The pool-seq data allowed usto identify over 20 million polymorphic sites within the S. fulvus genome. Analysis of a subset of the polymorphic sites indicated essentially no population genetic structureamong sites in the transect. This suggests that the dispersal capabilities of S. fulvus areconsiderable and that insecticide-resistance or otherwise undesirable alleles can spreadrapidly over large distances. The draft genome / pool-seq approach we took for thisstudy allowed us to evaluate gene flow quickly and inexpensively. In addition, it alsogave us access to the sequences of genes with a potential role in the mechanism ofinsecticide resistance.