The Genome and Population Structure of the Spruce Beetle, Dendroctonus rufipennis (Kirby, 1837), a Transcontinental Pest of North American Spruce

The spruce bark beetle Dendroctonus rufipennis (Family: Curculionidae; Subfamily Scolytinae) is a major forest insect pest throughout the transcontinental range of spruce species (Picea spp.) in North America. Here, we present an annotated, near chromosome-level, genome assembly of 271 Mb, with 86% of the assembly contained in 16 pseudochromosomes and containing 17,778 predicted gene models. We also annotated 13 protein-coding genes, 2 rRNAs, and 22 tRNAs in its 19,637 bp mitochondrial genome. In addition, we present the annotated complete nuclear and mitochondrial genomes of an associated endoparasitic nematode, Contortylenchus sp. T'it'q'et (Order: Tylenchida; Family: Allantonematidae). Its nuclear genome assembly was 76.2 Mb, with 99.8% of the assembly contained in nine pseudochromosomes and containing 12,208 predicted gene models. We also annotated 12 protein-coding genes, 2 rRNAs, and 22 tRNAs in its extremely AT-rich, 15,509 bp mitochondrial genome. Population genomic analyses revealed broad consistencies with past microsatellite work, supporting the hypothesis of multiple range expansions from glacial refugia. Our analyses also identified alternate modes of population diversification which suggest that both neutral and non-neutral processes may be shaping current population genetic structure across the spruce beetle range.