Department of Zoology, Faculty of Science, Charles University in Prague, Prague, Czech Republic.
PLoS One. 2013 Sep 16;8(9):e73806. doi: 10.1371/journal.pone.0073806. eCollection 2013.
Intraspecific cleptoparasitism represents a facultative strategy advantageous for reducing time and energy costs. However, only a few studies about nesting dynamics have described intraspecific cleptoparasitic behaviour in obligate solitary bees. We focused on nesting dynamics with the characterisation of nest owner replacements and frequency of true usurpation in four aggregating species belonging to different phylogenetic lineages--Andrena vaga (Andrenidae), Anthophora plumipes (Apidae), Colletes cunicularius (Colletidae), and Osmia rufa (Megachilidae). Our study, based on the regular observation of individually marked females, shows that nest owner replacement affects 10-45% of nests across all of the studied species and years. However, 39-90% of these nests had been abandoned before owner change and thus true nest usurpations represent only a part of observed nest replacement cases. Females tend to abandon their nests regularly and found new ones when they live long enough, which is in accordance with risk-spreading strategy. We suggest that the original facultative strategy of observed solitary bees during nest founding is not cleptoparasitism per se but rather reuse of any pre-existing nest (similar to "entering" strategy in apoid wasps). This is supported by gradual increase of nests founded by "entering" during the season with an increase in the number of available nests. Although the frequent reuse of conspecific nests results in frequent contact between solitary females, and rarely, in the short-term coexistence of two females in one nest, we detected unexpectedly low level of conflict in these neighbourhood societies. We suggest that nesting dynamics with regular nest switching and reusing reduces long-term and costly intraspecific aggression, a key factor for the origin and evolution of sociality.
种内巢寄生代表了一种有利于减少时间和能量成本的兼性策略。然而，只有少数关于筑巢动态的研究描述了专性独居蜂中的种内巢寄生行为。我们专注于筑巢动态，对属于不同进化谱系的四个聚集物种的巢主更替和真正篡夺的频率进行了特征描述——Andrena vaga（切叶蜂科）、Anthophora plumipes（蜜蜂科）、Colletes cunicularius（熊蜂科）和 Osmia rufa（木蜂科）。我们的研究基于对单独标记的雌性的定期观察，表明巢主更替影响了所有研究物种和年份的 10-45%的巢。然而，这些巢中有 39-90%在主人更换之前就已经被遗弃，因此真正的巢篡夺只代表了观察到的巢更换案例的一部分。当雌性活得足够长时，它们会定期放弃巢穴并找到新的巢穴，这符合风险分散策略。我们认为，所观察到的独居蜂在筑巢时最初的兼性策略本身并不是巢寄生，而是对任何预先存在的巢穴的再利用（类似于膜翅目黄蜂中的“进入”策略）。这一观点得到了以下事实的支持：随着可用巢穴数量的增加，“进入”筑巢的巢穴在季节中逐渐增加。尽管同种巢穴的频繁再利用导致了独居雌性之间的频繁接触，但很少有两种雌性在一个巢中短期共存，我们出人意料地发现这些邻里社会中的冲突水平很低。我们认为，定期更换和重复使用巢穴的筑巢动态减少了长期和昂贵的种内攻击，这是社会性起源和进化的关键因素。
