Wireworm (Coleoptera: Elateridae) genomic analysis reveals putative cryptic species, population structure, and adaptation to pest control

Wireworms, the larvae of click beetles (Coleoptera: Elateridae), are agricultural pests that are causing increasing economic damage to cereal, potato, and vegetable crops worldwide. In BC, Alberta, Montana, and the Pacific Northwest, some of the most important pest species belong to the genus Limonius, particularly L. californicus, L. infuscatus, and L. canus. The biology of these species is poorly understood, and they are difficult to separate morphologically. This paper presents results of a project led by the University of Idaho, in which specimens of all three species, collected from different Provinces and States, were sequenced and compared. This produced the first genome assembly of a pest wireworm (L. californicus), and, using genome-wide markers (RADseq) and genome skimming, allowed for an investigation of the population structure and phylogenetic relationships of these three species across this area. It appears that both L. californicus and L. infuscatus are comprised of genetically distinct but morphologically indistinguishable groups, and these species could therefore be considered cryptic species complexes. Genome scans for selection also provide evidence for adaptation associated with different pesticide treatments in an agricultural field trial for L. canus. These results demonstrate that genomic tools can help in the development of effective wireworm control strategies. These data can potentially be used to develop species-specific primers that can be used for rapid, PCR-based species identification. Together with ongoing research, led by AAFC, into the development of new sex pheromones for these species, such ID tools will significantly increase our ability to manage these pests.