A Highly Contiguous Genome Assembly of a Major Forest Pest, the Eurasian Spruce Bark Beetle Ips Typographus

Abstract

Conifer-feeding bark beetles are important herbivores and decomposers in forest ecosystems. These species have evolved specializations to complete their life cycle in nutritionally poor wooden substrates and some can overwhelm tree defences and kill enormous numbers of trees during population outbreaks. The Eurasian spruce bark beetle (Ips typographus) is one tree-killing species; during a recent epidemic it destroyed >100 million m3 of spruce in a single year. We report a 236 Mb, highly contiguous I. typographus genome assembly using PacBio long-read sequencing. The final phased assembly had a contig N50 of 6.65 Mb in 272 contigs and was predicted to contain 23,923 protein-coding genes. Comparative genomic analysis including 11 additional coleopterans revealed expanded gene families associated with plant cell wall degradation, including pectinases, aspartyl proteases, and glycosyl hydrolases. This first whole-genome sequence from the genus Ips provides timely resources to address important questions about the evolutionary biology of the true weevils (Curculionidae), one of the most species-rich animal families. This resource will also allow for improved studies of functional genomics of both fundamental and applied value. In forests of today, increasingly stressed by global warming, this draft genome may ultimately assist in developing novel pest control strategies to mitigate outbreaks.

Chromosome‐level genome assembly reveals genomic architecture of northern range expansion in the mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae)

“…At present, genomes have been published for only two other bark beetle species (Curculionidae: Scolytinae): the coffee borer beetle, Hypothenemus hampei (Ferrari) (Vega et al, 2015), and the European spruce bark beetle, Ips typographus L. (Powell et al, 2020). Although the latter was completed with long‐read PacBio sequences, our use of the complementary approaches of proximity ligation sequencing and linkage map data for scaffolding existing draft genomes resulted in more contiguous assemblies.…”