Data from: Ancient symbiosis confers desiccation resistance to stored grain pest beetles

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, e.g. 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.

昆虫的微生物共生菌可为宿主赋予一系列在生物互作情境中有益的生态性状。然而，学界对昆虫共生菌介导宿主适应非生物环境（如温度、湿度）的机制仍知之甚少。本研究报道了一类古老的胞内、定位于含菌体的拟杆菌门(Bacteroidetes)共生菌，它们与系统发育距离较远的锯谷盗科(Silvanidae)和长蠹科(Bostrichidae)的谷物与林木蛀食甲虫共生。在锯谷盗（Oryzaephilus surinamensis）中，我们证实该共生菌可调控宿主的体壁厚度、黑化程度与碳氢化合物谱，提升其抗干燥能力，进而在干旱环境下显著增强宿主适合度。结合此前关于共生菌参与象鼻虫体壁生物合成的研究报道，本研究结果表明，趋同获得细菌共生伙伴是多种蛀食甲虫类群得以在谷物仓储设施典型的低湿环境中存活与增殖的关键适应性策略。