Linking pollen foraging of megachilid bees to their nest bacterial microbiota. Bee-Foraging-Microbiota: Bacteria

Microbial profiling of the solitary bee nest environment is a challenging task due to the multiple aspects of the solitary bee ecology. Solitary bees build their nests by modifying the interior of natural cavities using various environmental materials and they provision them with food by importing collected pollen. As a result, the microbiota of the solitary bee nests depends on a variety of introduced materials. In order to characterize the extent to which introduced pollen affects the nest microbiome, we used metabarcoding of the ITS2 rDNA and the 16S rDNA to characterize the pollen composition and the bacterial communities of 100 solitary bee nest chambers belonging to seven megachilid species. Although the identity of each bee host species was the main driver of variance for the nest bacterial communities, pollen composition also had an effect on their structure. We found a weak correlation between bacterial and pollen alpha-diversity and significant interactions between the composition of pollen and that of the nest microbiota. This study contributes to the understanding of the association between foraging preferences and bacteria acquisition for solitary bees which cannot establish bacterial transmission routes through eusociality. This association may be essential for the successful offspring recruitment for this group of valuable pollinators.

由于独居蜂生态学具有多方面的复杂特征，对其巢穴环境开展微生物组谱分析是一项颇具挑战性的任务。独居蜂会借助各类环境材料改造天然洞穴内部以构筑巢穴，并通过运入采集得到的花粉为巢穴储备食物。由此，独居蜂巢穴的微生物组组成取决于多种引入性材料。
为明确引入的花粉对巢穴微生物组的影响程度，我们采用ITS2核糖体DNA（ITS2 rDNA）与16S核糖体DNA（16S rDNA）的元条形码测序（metabarcoding）技术，对隶属于7个切叶蜂科物种的100个独居蜂巢穴室的花粉组成与细菌群落进行了表征。
尽管各宿主蜂种的身份是巢穴细菌群落变异的主要驱动因子，花粉组成同样对其群落结构存在影响。研究发现，细菌群落与花粉的α多样性之间存在弱相关性，且花粉组成与巢穴微生物组组成之间存在显著的交互作用。
本研究有助于解析独居蜂的觅食偏好与细菌获取之间的关联——这类蜂无法通过真社会性途径建立细菌传播路径。此种关联对于这类具有重要生态价值的传粉昆虫的子代成功招募而言，可能是不可或缺的。