Large Shift in Symbiont Assemblage in the Invasive Red Turpentine Beetle

Abstract

Changes in symbiont assemblages can affect the success and impact of invasive species, and may provide knowledge regarding the invasion histories of their vectors. Bark beetle symbioses are ideal systems to study changes in symbiont assemblages resulting from invasions. The red turpentine beetle (Dendroctonus valens) is a bark beetle species that recently invaded China from its native range in North America. It is associated with ophiostomatalean fungi in both locations, although the fungi have previously been well-surveyed only in China. We surveyed the ophiostomatalean fungi associated with D. valens in eastern and western North America, and identified the fungal species using multi-gene phylogenies. From the 307 collected isolates (147 in eastern North America and 160 in western North America), we identified 20 species: 11 in eastern North America and 13 in western North America. Four species were shared between eastern North America and western North America, one species (Ophiostoma floccosum) was shared between western North America and China, and three species (Grosmannia koreana, Leptographium procerum, and Ophiostoma abietinum) were shared between eastern North America and China. Ophiostoma floccosum and O. abietinum have worldwide distributions, and were rarely isolated from D. valens. However, G. koreana and L. procerum are primarily limited to Asia and North America respectively. Leptographium procerum, which is thought to be native to North America, represented >45% of the symbionts of D. valens in eastern North America and China, suggesting D. valens may have been introduced to China from eastern North America. These results are surprising, as previous population genetics studies on D. valens based on the cytochrome oxidase I gene have suggested that the insect was introduced into China from western North America.

Multiorganismal Insects: Diversity and Function of Resident Microorganisms

“…Monitoring may be particularly valuable for exotic insect species, whose invasiveness can depend on interactions with microorganisms in the introduced range. For example, the US turpentine beetle Dendroctonus valens (Scolytinae) is a minor forestry pest in its native range, but it has been causing high mortality to Chinese pines since its introduction to China in the 1980s (108), partly because of its acquisition of fungi from local Chinese Scolytinae (109). By contrast, Megacopta cribraria , introduced from eastern Asia to the eastern United States in 2009, appears to have retained the ancestral Ishikawaella symbiont; and its rapid transfer to soybean crops in the United States is not linked to symbiont switching (12).…”

Complex patterns of global spread in invasive insects: eco-evolutionary and management consequences

“…Invasive insects, for example, bring with them a suite of obligate and facultative symbionts, including mutualists, parasites and commensals, some of which can have important effects on fitness (Dillon and Dillon 2004;Moran 2007). In addition, there is growing evidence of symbiont switching in novel communities (Werren et al 2008;Taerum et al 2013). For example, increased performance and the production of female-biased offspring in Rickettsia-infected whiteflies (Bemisi tabaci) provide a strong case for the role of a facultative endosymbiont in the insect's invasion in California (Himler et al 2011;Lawson Handley et al 2011).…”

Know your farmer: Ancient origins and multiple independent domestications of ambrosia beetle fungal cultivars

“…Past efforts to definitively reconstruct evolutionary relationships among Ophiostomatales genera have been inconclusive. The inferred phylogenies were often poorly supported, or the relationships among taxa were unstable across studies, with results varying depending on the taxa or loci sampled, and on the phylogenetic methods employed (Bateman et al., ; Dreaden et al., ; Massoumi Alamouti, Tsui, & Breuil, ; Musvuugwa et al., ; Taerum et al., ). Phylogenetic uncertainty makes it difficult to address long‐standing questions regarding the timing and number of domestication events for ambrosial cultivars in the Ophiostomatales (Dreaden et al., ).…”

“…Past efforts to definitively reconstruct evolutionary relationships among Ophiostomatales genera have been inconclusive. The inferred phylogenies were often poorly supported, or the relationships among taxa were unstable across studies, with results varying depending on the taxa or loci sampled, and on the phylogenetic methods employed (Bateman et al, 2017;Dreaden et al, 2014;Massoumi Alamouti, Tsui, & Breuil, 2009;Musvuugwa et al, 2015;Taerum et al, 2013).…”