Research Group Insect Symbiosis, Max-Planck-Institute for Chemical Ecology, Jena, Germany.
Department for Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg-University, Mainz, Germany.
Mol Ecol. 2018 Apr;27(8):2095-2108. doi: 10.1111/mec.14418. Epub 2017 Nov 29.
Microbial symbionts of insects provide a range of ecological traits to their hosts that are beneficial in the context of biotic interactions. However, little is known about insect symbiont-mediated adaptation to the abiotic environment, for example, temperature and humidity. Here, we report on an ancient clade of intracellular, bacteriome-located Bacteroidetes symbionts that are associated with grain and wood pest beetles of the phylogenetically distant families Silvanidae and Bostrichidae. In the saw-toothed grain beetle Oryzaephilus surinamensis, we demonstrate that the symbionts affect cuticle thickness, melanization and hydrocarbon profile, enhancing desiccation resistance and thereby strongly improving fitness under dry conditions. Together with earlier observations on symbiont contributions to cuticle biosynthesis in weevils, our findings indicate that convergent acquisitions of bacterial mutualists represented key adaptations enabling diverse pest beetle groups to survive and proliferate under the low ambient humidity that characterizes dry grain storage facilities.
昆虫的微生物共生体为其宿主提供了一系列有益于生物相互作用的生态特征。然而，对于昆虫共生体如何适应非生物环境（例如温度和湿度），人们知之甚少。在这里，我们报告了一个古老的、位于细菌体腔中的拟杆菌门共生体的分支，它们与亲缘关系较远的 Silvanidae 和 Bostrichidae 科的谷物和木材害虫甲虫有关。在锯齿谷象 Oryzaephilus surinamensis 中，我们证明了这些共生体影响了表皮厚度、黑化和碳氢化合物分布，增强了耐旱性，从而在干燥条件下极大地提高了适应性。结合之前关于共生体对象甲类昆虫表皮生物合成贡献的观察结果，我们的发现表明，对细菌共生体的趋同获取是关键的适应策略，使不同的害虫甲虫类群能够在干燥谷物储存设施所特有的低环境湿度下生存和繁殖。
