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

Kimberly R Andrews,Daniel D New,Matthew W Fagnan,Robert Vernon,Willem G Van Herk,Paul A Hohenlohe,David W Crowder,Alida Gerritsen,Silvia I Rondon,Arash Rashed,Cathy M Wilson,Kevin W Wanner,Samuel S Hunter

doi:10.1038/s42003-020-01169-9

Abstract

The larvae of click beetles (Coleoptera: Elateridae), known as “wireworms,” are agricultural pests that pose a substantial economic threat worldwide. We produced one of the first wireworm genome assemblies (Limonius californicus), and investigated population structure and phylogenetic relationships of three species (L. californicus, L. infuscatus, L. canus) across the northwest US and southwest Canada using genome-wide markers (RADseq) and genome skimming. We found two species (L. californicus and L. infuscatus) are comprised of multiple genetically distinct groups that diverged in the Pleistocene but have no known distinguishing morphological characters, and therefore could be considered cryptic species complexes. We also found within-species population structure across relatively short geographic distances. Genome scans for selection provided preliminary evidence for signatures of adaptation associated with different pesticide treatments in an agricultural field trial for L. canus. We demonstrate that genomic tools can be a strong asset in developing effective wireworm control strategies.

Highlights

The larvae of click beetles (Coleoptera: Elateridae), known as “wireworms,” are agricultural pests that pose a substantial economic threat worldwide
We focus on three wireworm species that are resurging as pests: Limonius californicus Mannerheim, L. infuscatus Motschulsky, and L. canus LeConte (Fig. 1)[22,23]
We identified genetic lineages within both L. californicus and L. infuscatus that were highly divergent for both restriction site-associated DNA sequencing (RADseq) and mitochondrial DNA (mtDNA) markers, potentially indicating the presence of cryptic species complexes

Summary

Introduction

The larvae of click beetles (Coleoptera: Elateridae), known as “wireworms,” are agricultural pests that pose a substantial economic threat worldwide. Knowledge of wireworm species composition and population structure is often limited, thereby reducing the ability to design and implement IPM strategies One reason for this lack of information is that wireworm species in the larval stage are difficult to identify morphologically due to a lack of clear distinguishing characters between species; only a limited number of experts in the field are able to distinguish some species. DNA barcoding efforts on wireworms from North America, Europe, and other regions have demonstrated that portions of the cytochrome oxidase I (COI) gene and 16S ribosomal DNA (rDNA) are effective mtDNA markers for distinguishing known species[15,16,17,18,19] These studies found genetic evidence for the presence of wireworm species that were previously undescribed due to the absence of distinct morphological traits between them (cryptic species), indicating that the number of wireworm species may currently be underestimated. Despite the strong potential utility of genetic approaches for the development of effective IPM for wireworms, to our knowledge no population genetic or genome scan approaches have been conducted for wireworm species

Methods

Results

Conclusion