The impacts of multiple environmental stressors on native bee populations

蜜蜂对于食物生产和维持健康多样的野生植物是必不可少的。他们的授粉服务占全球农作物产量的35%，每年价值至少2400亿加元。坏消息是，蜜蜂正在苦苦挣扎，我们迫切需要了解全球蜜蜂数量下降的原因，以免它们提供的授粉服务无法满足我们的食物生产需求。目前的想法是，蜜蜂数量的减少是许多个体因素共同作用的结果，这些因素使蜜蜂承受着巨大的压力。与受管理的蜜蜂不同，加拿大的800多种本地蜜蜂免费提供作物授粉服务，但人们对它们如何应对环境压力知之甚少。我的研究项目将评估一系列环境压力因素对本地蜜蜂、它们的蜂群和种群的影响。关键的是，它还将考虑诸如栖息地丧失、疾病、杀虫剂和营养不良等压力因素的综合影响。通过一系列的实验室和实地研究，我们将分别确定大黄蜂和独居蜜蜂在野外暴露于每一种应激源的相关水平的影响。我们将研究每种应激源对重要的个体行为的影响，如觅食、学习和导航，以及随后个体行为损害对独居蜜蜂繁殖成功的直接影响，以及通过减少群体生长间接影响熊蜂群体繁殖的影响。在确定了这些压力源的相对重要性后，我们将以成对和三向组合的方式评估它们的影响。一个关键的问题是，每个应激源的影响是叠加在一起(相加效应)，还是联合暴露的影响远大于两部分之和(协同效应)。学习和记忆是动物在一生中适应环境变化的关键机制。我们将测试学习和记忆的变化对蜜蜂群体在不同压力水平的环境中生存有多大帮助。如果花更难找到，那么学习速度更快的蜜蜂是一个优势，它们能产生更多的后代吗？学习在蜜蜂导航中也起着核心作用。使用尖端的无线电标签技术，我们将跟踪蜜蜂在一系列景观中觅食和分散的情况，以评估它们如何应对农业和城市集约化梯度上日益分散的适宜栖息地。一个重要的保护问题是，独居蜜蜂是否比群居蜜蜂对环境压力更敏感。蜂群的社会组织是否为大黄蜂和蜜蜂抵御环境压力提供了缓冲？除了提供卓越的科学成果和对知识进步的重大贡献外，这项研究还与环境、保护和农业问题具有直接的政策相关性。

Bees are essential to food production and maintaining healthy and diverse wild plants. Their pollination services are responsible for 35% of global crop production worth at least $240 Billion CAD per year. The bad news is that bees are struggling and we urgently need to understand the causes of global declines before the pollination services they provide fail to meet our food production needs. Current thinking is that bee declines are the result of many individual factors combining to place them under great stress. Unlike managed honeybees, Canada’s 800+ native bee species provide their crop pollination services free of charge, however much less is known about how they respond to environmental stress. My research program will assess the impacts of a range of environmental stress factors on native bees, their colonies and populations. Critically it will also consider the combined impacts of stressors, such as habitat loss, disease, pesticides and poor nutrition. Using a series of laboratory and field studies we will determine the impacts of field relevant levels of exposure to each of these stressors individually for both bumblebees and solitary bees. We will examine the impacts of each stressor on important individual behaviours, such as foraging, learning and navigation, and the subsequent effects of individual behavioural impairment directly on the reproductive success of solitary bees, and indirectly on bumblebee colony reproduction mediated by reduced colony growth. Having established the relative importance of these stressors we will assess their impacts in pairwise and three-way combinations. A key question is whether effects of each stressor pile up (additive effect), or whether the effects of combined exposure are much greater than the sum of both parts (synergistic effect). Learning and memory are critical mechanisms allowing animals to adapt to environmental change during their lifetime. We will test how useful variation in learning and memory is for bee colonies to survive in environments with different levels of stress. If flowers are harder to find are faster learning bees at an advantage, and can they produce more offspring? Learning also plays a central role in bee navigation. Using cutting edge radio tag technology we will track bees as they forage and disperse across a range of landscapes to assess how they respond to increasingly fragmented patches of suitable habitat along gradients of agricultural and urban intensification. An important conservation question is whether solitary bees are more sensitive to environmental stress than social bees. Does the social organization of a colony provide a buffer for bumblebee and honeybees against environmental stress? In addition to delivering scientific excellence with substantial contributions to the advancement of knowledge, this research has direct policy relevance for environmental, conservation and agricultural issues.