Taerum Stephen J, Duong Tuan A, de Beer Z Wilhelm, Gillette Nancy, Sun Jiang-Hua, Owen Donald R, Wingfield Michael J
Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa.
PLoS One. 2013 Oct 18;8(10):e78126. doi: 10.1371/journal.pone.0078126. eCollection 2013.
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.
共生体组合的变化会影响入侵物种的成功与影响，并且可能提供有关其传播媒介入侵历史的知识。树皮甲虫共生关系是研究入侵导致的共生体组合变化的理想系统。红脂大小蠹（Dendroctonus valens）是一种树皮甲虫，最近从其在北美的原生地入侵到中国。它在两个地区都与长喙壳菌纲真菌有关联，尽管此前仅在中国对这些真菌进行过充分调查。我们调查了北美东部和西部与红脂大小蠹相关的长喙壳菌纲真菌，并使用多基因系统发育分析来鉴定真菌物种。从收集的307个分离株（北美东部147个，北美西部160个）中，我们鉴定出20个物种：北美东部11个，北美西部13个。北美东部和北美西部共有4个物种，北美西部和中国共有1个物种（絮状长喙壳菌Ophiostoma floccosum），北美东部和中国共有3个物种（韩国格氏菌Grosmannia koreana、长喙细孔菌Leptographium procerum和冷杉长喙壳菌Ophiostoma abietinum）。絮状长喙壳菌和冷杉长喙壳菌分布于全球，很少从红脂大小蠹中分离得到。然而，韩国格氏菌和长喙细孔菌分别主要局限于亚洲和北美。长喙细孔菌被认为原产于北美，在北美东部和中国的红脂大小蠹共生体中占比超过45%，这表明红脂大小蠹可能是从北美东部引入中国的。这些结果令人惊讶，因为此前基于细胞色素氧化酶I基因对红脂大小蠹进行的种群遗传学研究表明，该昆虫是从北美西部引入中国的。
