Climate change is rapidly warming thermal environments, an important abiotic stimulus governing interactions between microbial symbionts and their hosts. Increasing evidence suggests that solitary bees rely on pollen provision microbes for successful development. However, the effects of heat stress on provision microbiota and the resulting consequences for larval health and development remain to be examined. We performed an in vitro study to investigate the effects of the thermal environment on provision microbiome composition and measured fitness outcomes for Osmia lignaria larvae. While pollen sterilisation removed bacteria from microbe‐rich provisions, larval survivorship did not significantly differ between bees reared on microbe‐rich (unmanipulated) diets and provisions treated with ethylene oxide (EO) gas. In contrast to previous research in solitary bees, larvae reared on EO‐treated provisions weighed more and had higher total fat content, with temperature moderating the degree of difference. As anticipated, we observed a negative relationship between the duration of larval development and temperature. Our results indicated that an intact provision microbiota may not always improve bee fitness and that bee‐microbe interactions during larval development may contribute to the size‐shrinking effect observed for cavity‐nesting bees under warming conditions.

中文翻译：

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气候变化中的蜜蜂微生物组：研究温度对独居蜜蜂生活史和健康的影响


气候变化正在迅速变暖热环境，这是控制微生物共生体与其宿主之间相互作用的重要非生物刺激。越来越多的证据表明，独居蜜蜂依靠花粉提供的微生物来成功发育。然而，热应激对供应微生物群的影响以及由此对幼虫健康和发育的影响仍有待研究。我们进行了一项体外研究，以调查热环境对 Osmia lignaria 幼虫提供微生物组组成和测量适应性结果的影响。虽然花粉绝育从富含微生物的饲料中去除了细菌，但在富含微生物（未操纵）的饮食中饲养的蜜蜂与用环氧乙烷 （EO） 气体处理的蜜蜂之间，幼虫存活率没有显着差异。与之前对独居蜜蜂的研究相比，使用 EO 处理的食物饲养的幼虫更重，总脂肪含量更高，温度缓和了差异的程度。正如预期的那样，我们观察到幼虫发育的持续时间与温度之间存在负相关关系。我们的结果表明，完整的微生物群可能并不总是能改善蜜蜂的健康状况，并且幼虫发育过程中的蜜蜂与微生物的相互作用可能有助于在温暖条件下观察到的空腔筑巢蜜蜂的尺寸缩小效应。