The gut microbiota influences animal neurodevelopment and behaviour but has not previously been documented to affect group-level properties of social organisms. Here, we use honeybees to probe the effect of the gut microbiota on host social behaviour. We found that the microbiota increased the rate and specialization of head-to-head interactions between bees. Microbiota colonization was associated with higher abundances of one-third of the metabolites detected in the brain, including amino acids with roles in synaptic transmission and brain energetic function. Some of these metabolites were significant predictors of the number of social interactions. Microbiota colonization also affected brain transcriptional processes related to amino acid metabolism and epigenetic modifications in a brain region involved in sensory perception. These results demonstrate that the gut microbiota modulates the emergent colony social network of honeybees and suggest changes in chromatin accessibility and amino acid biosynthesis as underlying processes.

肠道微生物群影响动物的神经发育和行为，但此前尚未有证据表明肠道微生物群会影响社会有机体的群体水平特性。在这里，我们利用蜜蜂来探究肠道微生物群对宿主社会行为的影响。我们发现微生物群提高了蜜蜂之间头对头相互作用的速度和专业化。微生物群定植与大脑中检测到的三分之一代谢物的丰度较高有关，其中包括在突触传递和大脑能量功能中发挥作用的氨基酸。其中一些代谢物是社交互动次数的重要预测因子。微生物群定植还影响与氨基酸代谢相关的大脑转录过程以及涉及感觉知觉的大脑区域的表观遗传修饰。这些结果表明，肠道微生物群调节蜜蜂的新兴群体社交网络，并表明染色质可及性和氨基酸生物合成的变化是潜在过程。