The mushroom body (MB) is an area of the insect brain involved in learning, memory, and sensory integration. Here, we used the sweat bee Megalopta genalis (Halictidae) to test for differences between queens and workers in the volume of the MB calyces. We used confocal microscopy to measure the volume of the whole brain, MB calyces, optic lobes, and antennal lobes of queens and workers. Queens had larger brains, larger MB calyces, and a larger MB calyces:whole brain ratio than workers, suggesting an effect of social dominance in brain development. This could result from social interactions leading to smaller worker MBs, or larger queen MBs. It could also result from other factors, such as differences in age or sensory experience. To test these explanations, we next compared queens and workers to other groups. We compared newly emerged bees, bees reared in isolation for 10 days, bees initiating new observation nests, and bees initiating new natural nests collected from the field to queens and workers. Queens did not differ from these other groups. We suggest that the effects of queen dominance over workers, rather than differences in age, experience, or reproductive status, are responsible for the queen–worker differences we observed. Worker MB development may be affected by queen aggression directly and/or manipulation of larval nutrition, which is provisioned by the queen. We found no consistent differences in the size of antennal lobes or optic lobes associated with differences in age, experience, reproductive status, or social caste.

中文翻译：

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女王的统治地位可能会减少社交蜜蜂中工人蘑菇的体型。

蘑菇体（MB）是昆虫大脑中参与学习，记忆和感觉整合的区域。在这里，我们使用了汗蜂Megalopta genalis（Halictidae），以测试皇后与工人之间MB萼片的体积差异。我们使用共聚焦显微镜来测量皇后和工人的整个大脑，MB萼，视裂和触角裂的体积。皇后区的大脑比工人大，MB的花萼更大，MB的花萼：整个大脑的比例比工人大，这表明社交优势对大脑发育有影响。这可能是由于社交互动导致较小的工作人员MB或较大的女王MB。这也可能是由其他因素引起的，例如年龄或感官体验的差异。为了检验这些解释，我们接下来将皇后和工人与其他群体进行了比较。我们比较了新出现的蜜蜂，隔离饲养的蜜蜂10天，启动新观测巢的蜜蜂以及启动从田间收集到皇后和工人的新自然巢的蜜蜂。皇后区与其他人群没有不同。我们认为，皇后统治对工人的影响，而不是年龄，经验或生殖状况的差异，是造成我们观察到的皇后工人差异的原因。蚁后的直接攻击和/或幼虫营养的操作可能会影响工人的MB发育，这是由女王提供的。我们没有发现与年龄，经验，生殖状况或社会种姓的差异相关的触角或视叶大小的一致性差异。蚁后的直接攻击和/或幼虫营养的操作可能会影响工人的MB发育，这是由女王提供的。我们没有发现与年龄，经验，生殖状况或社会种姓的差异相关的触角或视叶大小的一致性差异。蚁后的直接攻击和/或幼虫营养的操作可能会影响工人的MB发育，这是由女王提供的。我们没有发现与年龄，经验，生殖状况或社会种姓的差异相关的触角或视叶大小的一致性差异。