Insights into longhorn beetle (Cerambycidae) evolution from comparative analyses of the red-headed ash borer (Neoclytus acuminatus acuminatus) genome.

Abstract

Neoclytus acuminatus acuminatus (NACU), the red-headed ash borer, is a wood-boring longhorn beetle (Cerambycidae: Cerambycinae) native to North America and introduced in Eurasia and South America. Its larvae develop in dying or recently dead hardwood trees, including ecologically and economically significant species of ash, hickory, and oak. We sequenced, assembled, and annotated the genome of a female NACU, and compared it to the publicly available genomes of other cerambycid species. The 508 Mb NACU genome assembly spanned 20 contigs (19 nuclear + 1 mitochondrial), with an N50 of 52.59 Mb and largest contig of 61.20 Mb. A moderately high fraction of the genome (62.63%) comprised repetitive sequences, with nearly all (99.4%) expected orthologous genes (BUSCOs) present and fully assembled. We identified two contigs as fragments of the NACU sex chromosome. Genome annotation identified 12,899 genes, including 109 putative horizontally transferred loci. Synteny analysis identified well-conserved blocks of collinearity between the NACU genome and other Cerambycidae. The genome contains a similar number of genes encoding putative plant cell wall degrading enzymes as other Cerambycidae. The NACU genome provides new insights into genome evolution in the family Cerambycidae, known for its rich diversity of xylophagous species, and provides a new viewpoint from which to study the evolution and genomic basis of traits such as wood-feeding and olfaction in beetles and other insects.