The impacts of multiple environmental stressors on native bee populations

点击翻译按钮获取中文摘要

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.