Social interactions may shape brain development. In primitively eusocial insects, the mushroom body (MB), an area of the brain associated with sensory integration and learning, is larger in queens than in workers. This may reflect a strategy of neural investment in queens or it may be a plastic response to social interactions in the nest. Here, we show that nest foundresses—the reproductive females who will become queens but are solitary until their first workers are born—have larger MBs than workers in the primitively eusocial sweat bee Augochlorella aurata. Whole brain size and optic lobe size do not differ between the two groups, but foundresses also have larger antennal lobes than workers. This shows that increased neural investment in MBs precedes social group formation. Larger MBs among foundresses may reflect the increased larval nutrition provisioned to future queens and the lack of social aggression from a dominant queen upon adult emergence.

中文翻译：

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社交种姓之间的大脑差异先于原始的社交性蜜蜂形成群体

社交互动可能会影响大脑发育。在原始的共社会昆虫中，皇后区的蘑菇体（MB）在大脑中的面积大于工人，这是与感觉统合和学习相关的大脑区域。这可能反映了对皇后区进行神经投资的策略，也可能是对巢中社交互动的可塑性反应。在这里，我们表明，巢穴的创建者（将成为女王，但直到第一批工人出生之前都是孤独的）的生殖能力要比原始的社会性汗蜂Augochlorella aurata的工人更大。。两组之间的全脑大小和视叶大小没有差异，但是女工的触角波瓣也比工人大。这表明对MB的神经投资增加是在社会群体形成之前。奠基者中较大的MB可能反映了提供给未来皇后的幼虫营养增加，以及成年后出现的优势皇后缺乏社会侵略性。