Genomic mechanisms of sympatric ecological and sexual divergence in a model agricultural pest, the European corn borer

•Populations of pest insects can vary in voltinism and sexual communication traits.•Clinal differences in circadian rhythm alleles impact local voltinism traits.•Male sexual response maps to a set of genes involved in neurogenesis.•QTL for diapause (voltinism) and male sexual response map to the Z-chromsome.•A segregating inversion has captured diapause and male sexual response loci. The European corn borer, Ostrinia nubilalis, is a model species for elucidating mechanisms underlying adaptively differentiated subpopulations in the face of reciprocal gene flow, and is a major pest of cultivated maize in North America and Eurasia. Strains are characterized by different pheromone communication systems in combination with voltinism strains that are adapted to distinct local climate and photoperiod through adjustments in diapause traits. However, only partial barriers to inter-strain hybridization exist in areas of sympatry. Recent research shows that genes governing important strain-specific isolating traits are disproportionately located on the Z-chromosome. Furthermore, co-adapted combinations of some of these genes are non-recombining due to location within a large chromosomal inversion, and assist in maintaining strain integrity despite hybridization.