Laboratory of Zoology, Department of Biology, University of the Balearic Islands, Cra, Valldemossa km 7.5, CP 07122, Palma, Illes Balears, Spain
Department of Entomology, University of California, Riverside, Riverside, CA 92521, USA.
Proc Biol Sci. 2018 Jun 13;285(1880). doi: 10.1098/rspb.2018.0761.
Bumblebees are among the world's most important groups of pollinating insects in natural and agricultural ecosystems. Each spring, queen bumblebees emerge from overwintering and initiate new nests, which ultimately give rise to workers and new reproductives later in the season. Nest initiation and survival are thus key drivers of both bumblebee pollination services and population dynamics. We performed the first laboratory experiment with the model bumblebee species that explores how early nesting success is impacted by the effects of temporary or more sustained exposure to sublethal levels of a neonicotinoid-type insecticide (imidacloprid at 5 ppb in nectar) and by reliance on a monofloral pollen diet, two factors that have been previously implicated in bumblebee decline. We found that queens exhibited increased mortality and dramatically reduced activity levels when exposed to imidacloprid, as well as delayed nest initiation and lower brood numbers in the nest, but partially recovered from these effects when they only received early, temporary exposure. The effects of pollen diet on individual queen- and colony-level responses were overshadowed by effects of the insecticide, although a monofloral pollen diet alone was sufficient to negatively impact brood production. These findings speak to the sensitivity of queen bumblebees during the nest initiation phase of the colony cycle, with implications for how queens and their young nests are uniquely impacted by exposure to threats such as pesticide exposure and foraging habitat unsuitability.
熊蜂是自然和农业生态系统中最重要的传粉昆虫类群之一。每年春天，蜂王从冬眠中苏醒，开始新的巢穴，最终在季节后期产生工蜂和新的繁殖蜂。因此，巢穴的建立和生存是影响熊蜂传粉服务和种群动态的关键因素。我们首次进行了实验室实验，研究了模型熊蜂物种的早期筑巢成功率如何受到以下因素的影响：暂时性或持续暴露于亚致死水平新烟碱类杀虫剂（花蜜中 5 ppb 的吡虫啉）的影响，以及依赖单一花粉饮食，这两个因素先前与熊蜂数量减少有关。我们发现，当暴露于吡虫啉时，蜂王的死亡率增加，活动水平显著降低，筑巢延迟，巢中幼虫数量减少，但当它们仅早期短暂接触时，这些影响会部分恢复。与杀虫剂的影响相比，花粉饮食对个体蜂王和群体水平反应的影响相形见绌，尽管单一花粉饮食本身就足以对幼虫的产生产生负面影响。这些发现表明，在蜂群周期的巢穴建立阶段，蜂王非常敏感，这对蜂王及其幼巢如何受到农药暴露和觅食栖息地不适等威胁的独特影响，以及对其幼巢的影响，具有重要意义。
