Data from: Gut microbiota of dung beetles correspond to dietary specializations of adults and larvae

Vertebrate dung is central to the dung beetle life cycle, constituting food for adults and a protective and nutritive refuge for their offspring. Adult dung beetles have soft mandibles and feed primarily on nutritionally rich dung particles, while larvae have sclerotized mandibles and consume coarser dung particles with a higher C/N ratio. Here, using the dung beetles Euoniticellus intermedius and E. triangulatus, we show that these morphological adaptations in mandibular structure are also correlated with differences in basic gut structure and gut bacterial communities between dung beetle life stages. Metagenome functional predictions based on 16S rDNA characterization further indicated that larval gut communities are enriched in genes involved in cellulose degradation and nitrogen fixation compared to adult guts. Larval gut communities are more similar to female gut communities than they are to those of males, and bacteria present in maternally provisioned brood balls and maternal ‘gifts’ (secretions deposited in the brood ball along with the egg) are also more similar to larval gut communities than to those of males. Maternal secretions and maternally provisioned brood balls, as well as dung, were important factors shaping the larval gut community. Differences between gut microbiota in the adults and larvae are likely to contribute to differences in nutrient assimilation from ingested dung at different life history stages.

脊椎动物粪便在蜣螂的生命周期中占据核心地位：它既是成虫的食物来源，同时也是其后代兼具保护性与营养性的栖息庇护场所。成虫蜣螂拥有柔软上颚，主要取食营养丰富的粪便颗粒；而幼虫则具有骨化上颚，以碳氮比更高的粗颗粒粪便为食。本研究以中间蜣螂（Euoniticellus intermedius）和三角蜣螂（E. triangulatus）为实验材料，证实了这种上颚结构的形态适应性，同时也与蜣螂不同生命阶段的肠道基础结构及肠道细菌群落差异密切相关。基于16S核糖体DNA（16S rDNA）表征的宏基因组功能预测进一步显示，相较于成虫肠道菌群，幼虫肠道菌群中富集了更多参与纤维素降解与固氮作用的功能基因。幼虫肠道菌群与雌性成虫肠道菌群的相似度，高于其与雄性成虫肠道菌群的相似度；同时，母体提供的育幼球以及母体“馈赠物”（即与卵一同沉积于育幼球中的分泌物）内的细菌群落，也与幼虫肠道菌群的相似度高于与雄性成虫肠道菌群的相似度。母体分泌物、母体提供的育幼球以及粪便，均是塑造幼虫肠道菌群的关键影响因素。成虫与幼虫的肠道微生物群落差异，可能会导致蜣螂在不同生命阶段从摄入粪便中进行营养同化的过程存在差异。