The name Xylocopa literally means “wood-cutter”, an apt name for the large, furry carpenter bees that bore tunnels in wood (it is also a more interesting common name than “large carpenter bee”). Most bees nest in relatively soft substrates such as soil or plant stems, which deteriorate without constant maintenance. In contrast, the sturdy nesting substrate used by many carpenter bees, especially those that nest in logs or lumber, deteriorates quite slowly, lasting for years or even decades. This means that nests may be used and re-used for generations. If a female can acquire a nest by inheritance or by quickly usurping a rival, she can avoid days of nest construction. It can take a female carpenter bee the better part of a week or more to excavate a burrow that is just big enough to produce perhaps four or five offspring (Richards and Course 2015). Acquiring access to a pre-existing nest through inheritance, usurpation, or sharing is easier, or at least less time-consuming than excavating a nest from scratch. Across the genus Xylocopa, competition for nests is a fundamental driver of social interactions among females, influencing whether they nest alone or in groups. Depending on the species, carpenter bee nests may start out as linear structures, with one or two tunnels branching off the nest entrance. Subsequent generations of females may lengthen or add tunnels. Although small nests have less space for brood cells, it is probably easier for occupants to defend the tunnels or entrance and to prevent other females from moving in. Large nests have more space for brood cells but are harder for a single female to monopolize. So, nest structure certainly influence whether carpenter bee females nest solitarily or in groups. It also influences other kinds of social interactions among females: competition for nest ownership or access can be severe, with females engaging in highly aggressive encounters to usurp or defend nest ownership or to establish social hierarchies when two or more females occupy the same nest (Gerling and Hermann 1978; Hogendoorn and Leys1993). In this issue, Madeleine Ostwald and colleagues investigate the “built environments” of so-called "teddy bear" carpenter bees, Xylocopa varipuncta1 (Ostwald et al. 2020). Investigating the built environments of carpenter bees is quite challenging because nests are located inside opaque substrates. While nests can be opened to see what is inside, destructive sampling limits how well we can assess changes in bee colonies or their nests over time. The solution is imaging techniques that allow us to look inside the nests without damaging them. Pioneering studies of carpenter bee behaviour relied on X-rays. Ostwald et al. update this approach using computerized tomography (CT) to scan two logs containing nests of teddy bear bees. Being able to look inside nests revealed changes in bee group size over time. Early in the breeding season (March in Arizona, USA) when females provision brood, most nests contained a single adult, presumably a female (CT scans do not allow females and males to be distinguished) nesting alone, but there was also evidence that some nests contained multiple females. For the rest of the year, nests were mostly occupied by multiple adults, as brood reached adulthood and remained in their natal nests. The number of nests occupied rose and fell throughout the year as some bees moved to new burrows. A novel angle of this research is demonstrating how nests change size and shape over the course of a breeding season and how this correlates with demographic changes. By imaging the same tunnels repeatedly, Ostwald et al. show that each year, tunnels get a little bit wider. This is because females scrape bits of wood off the sides of tunnels for fashioning into the sawdust partitions that separate brood cells. When the tunnels get wider, this influences how adult bees interact. Carpenter bees defend nest entrances and tunnels mainly by blocking them—friends may pass each other in tunnels, but foes may not. Once tunnels get too wide, females cannot prevent each other from passing through. When females cannot exclude each Insectes Sociaux

中文翻译：

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建筑环境影响木匠蜜蜂的社会性，反之亦然

Xylocopa 这个名字的字面意思是“伐木工”，这是对在木材中钻孔的大型毛茸茸的木蜂的恰当名称（它也是一个比“大木蜂”更有趣的通用名称）。大多数蜜蜂筑巢在相对柔软的基质中，例如土壤或植物茎，这些基质在没有持续维护的情况下会变质。相比之下，许多木蜂使用的坚固的筑巢基质，尤其是那些在原木或木材中筑巢的木蜂，退化非常缓慢，持续数年甚至数十年。这意味着巢可以被使用和重复使用几代。如果雌性可以通过继承或快速篡夺竞争对手的方式获得巢穴，她就可以避免数天的筑巢时间。一只雌性木蜂可能需要一周或更长时间才能挖出一个大到足以产生四五个后代的洞穴（Richards and Course 2015）。通过继承、篡夺或共享获得对预先存在的巢穴的访问权比从头开始挖掘巢穴更容易，或者至少耗时更少。在整个木瓜属中，对巢穴的竞争是雌性之间社会互动的基本驱动力，影响着它们是单独筑巢还是成群筑巢。根据物种的不同，木匠蜂巢最初可能是线性结构，从巢入口处分出一两个隧道。后代的雌性可能会延长或增加隧道。虽然小巢的育雏细胞空间较小，住户可能更容易保护隧道或入口并阻止其他雌性进入。大巢有更多的空间容纳育雏细胞，但单个雌性更难独占。因此，巢结构肯定会影响木蜂雌性是单独筑巢还是成群筑巢。它还影响雌性之间的其他类型的社会互动：对巢穴所有权或进入的竞争可能很激烈，当两个或更多雌性占据同一个巢穴时，雌性会进行高度侵略性的遭遇以篡夺或捍卫巢穴所有权或建立社会等级制度（Gerling和 Hermann 1978 年；Hogendoorn 和 Leys 1993 年）。在本期中，Madeleine Ostwald 及其同事调查了所谓的“泰迪熊”木蜂 Xylocopa varipuncta1（Ostwald 等人，2020 年）的“建筑环境”。调查木蜂的建筑环境非常具有挑战性，因为巢位于不透明的基材内。虽然可以打开巢穴查看里面有什么，但破坏性采样限制了我们评估蜂群或其巢穴随时间变化的能力。解决方案是成像技术，使我们能够在不损坏巢穴的情况下观察巢穴内部。对木蜂行为的开创性研究依赖于 X 射线。奥斯特瓦尔德等人。使用计算机断层扫描 (CT) 更新此方法以扫描包含泰迪熊蜜蜂巢穴的两个日志。能够看到蜂巢内部揭示了蜜蜂群体规模随着时间的推移而发生的变化。在繁殖季节早期（美国亚利桑那州的 3 月），当雌性提供育雏时，大多数巢穴中只有一个成虫，大概是雌性（CT 扫描无法区分雌性和雄性）单独筑巢，但也有证据表明，一些巢穴中含有多只雌性。在这一年余下的时间里，巢穴大多被多个成虫占据，因为幼鸟成年并留在它们出生的巢穴中。随着一些蜜蜂搬到新的洞穴，被占据的巢穴数量在一年中起起落落。这项研究的一个新角度是展示巢穴如何在繁殖季节期间改变大小和形状，以及这与人口变化的相关性。通过重复成像相同的隧道，Ostwald 等人。表明每年隧道都会变宽一点。这是因为雌性会从隧道的侧面刮掉一些木头，以形成分隔育细胞的锯末隔板。当隧道变宽时，这会影响成年蜜蜂的互动方式。木蜂主要通过阻挡它们来保护巢穴入口和隧道——朋友可能会在隧道中互相通过，但敌人可能不会。一旦隧道变得太宽，雌性就无法阻止彼此通过。当雌性不能排除每一个 Insectes Sociaux 时