Chromosome-level genome assembly and population genomic analyses provide insights into adaptive evolution of the red turpentine beetle, Dendroctonus valens

Abstract

Background Biological invasions are responsible for substantial environmental and economic losses. The red turpentine beetle (RTB), Dendroctonus valens LeConte, is an important invasive bark beetle from North America that has caused substantial tree mortality in China. The lack of a high-quality reference genome seriously limits deciphering the extent to which genetic adaptions resulted in a secondary pest becoming so destructive in its invaded area. Results Here, we present a 322.41 Mb chromosome-scale reference genome of RTB, of which 98% of assembled sequences are anchored onto fourteen linkage groups including the X chromosome with a N50 size of 24.36 Mb, which is significantly greater than other Coleoptera species. Repetitive sequences make up 45.22% of the genome, which is higher than four other Coleoptera species, i.e., Mountain pine beetle Dendroctonus ponderosae, red flour beetle Tribolium castaneum, blister beetle Hycleus cichorii, and Colorado potato beetle Leptinotarsa decemlineata. We identify rapidly expanded gene families and positively selected genes in RTB, which may be responsible for its rapid environmental adaptation. Population genetic structure of RTB was revealed by genome resequencing of geographic populations in native and invaded regions, suggesting substantial divergence of the North American population and illustrates the possible invasion and spread route in China. Selective sweep analysis highlighted the enhanced ability of Chinese populations in environmental adaptation. Conclusions Overall, our high-quality reference genome represents an important resource for genomics study of invasive bark beetles, which will facilitate the functional study and decipher mechanism underlying invasion success of RTB by integrating the Pinus tabuliformis genome.

β‐Pinene + ethanol attracts more red turpentine beetles than carene+ ethanol, with or without traces of frontalin, at prescribed burn or thinned sites

“…The North American source of D. valens transported to China may have come from one or more locations, but most likely within the West group and possibly the PNW based on genetic studies (Cai et al, 2008; Cognato et al, 2005; Z. Liu et al, 2022; Taerum et al, 2016), while origination from Central or Northeast populations is suggested by symbiont community analyses (Q. Lu, Decock et al, 2009; M. Lu, Zhou, et al, 2009; Taerum et al, 2013, 2016). Further refinement of the North American source(s) invading China may be provided by population's primary attraction responses to β‐pinene or carene.…”

“…Therefore, populations we have tested in Washington, Oregon and northeastern California, where β‐pinene produces the strongest response, can be removed from the source pool. Genomic analyses show northeastern California and western Montana populations to more closely align with beetles in China than US populations from Arizona‐Colorado, or Wisconsin‐Minnesota (Z. Liu et al, 2022). The California collection site for Z. Liu et al (2022) is in a general area where some D. valens populations respond more strongly to carene than β‐pinene (Erbilgin et al, 2007), while no comparison tests for these two kairomones have been conducted in Montana.…”

Chromosome-level genome assembly of Microplitis manilae Ashmead, 1904 (Hymenoptera: Braconidae)

“…The draft genome is obtained by first assembling long reads and then polishing the results with short reads, which has been widely used in genome assembly research for different organisms recently 14 – 18 . NextDenovo v2.5.0 ( https://github.com/Nextomics/NextDenovo ) was used to assemble the initial assembly with ONT sequences.…”

Tolerance to dietary linalool primarily involves co-expression of cytochrome P450s and cuticular proteins in Pagiophloeus tsushimanus (Coleoptera: Curculionidae) larvae using SMRT sequencing and RNA-seq

“…Notably, high-quality genomes of Dendroctonus spp. recently published provide valuable references for interaction studies between the Curculionoidea superfamily and their host terpenoids [47,48]. In this context, some rapidly expanded and positively selected genes related to metabolic capacity, including cytochrome P450 and glutathione S-transferase gene families, were thought to promote Dendroctonus adaptations to oleoresin terpenoids in conifers [48,49].…”

“…recently published provide valuable references for interaction studies between the Curculionoidea superfamily and their host terpenoids [47,48]. In this context, some rapidly expanded and positively selected genes related to metabolic capacity, including cytochrome P450 and glutathione S-transferase gene families, were thought to promote Dendroctonus adaptations to oleoresin terpenoids in conifers [48,49]. Consequently, in the future, genome sequence of P. tsushimanus deserves in-depth studies to perform a comparative analysis with genomes of Dendroctonus spp.…”