Data from: Chronic neonicotinoid pesticide exposure and parasite stress differentially affects learning in honeybees and bumblebees

Learning and memory are crucial functions which enable insect pollinators to efficiently locate and extract floral rewards. Exposure to pesticides or infection by parasites may cause subtle but ecologically important changes in cognitive functions of pollinators. The potential interactive effects of these stressors on learning and memory have not yet been explored. Furthermore, sensitivity to stressors may differ between species, but few studies have compared responses in different species. Here, we show that chronic exposure to field-realistic levels of the neonicotinoid clothianidin impaired olfactory learning acquisition in honeybees, leading to potential impacts on colony fitness, but not in bumblebees. Infection by the microsporidian parasite Nosema ceranae slightly impaired learning in honeybees, but no interactive effects were observed. Nosema did not infect bumblebees (3% infection success). Nevertheless, Nosema treated bumblebees had a slightly lower rate of learning than controls, but faster learning in combination with neonicotinoid exposure. This highlights the potential for complex interactive effects of stressors on learning. Our results underline that one cannot readily extrapolate findings from one bee species to others. This has important implications for regulatory risk assessments which generally use honeybees as a model for all bees.

学习与记忆是昆虫传粉者得以高效定位并获取花蜜报酬的核心功能。农药暴露或寄生虫感染，可能会对传粉者的认知功能造成微妙却在生态学层面具有重要意义的改变。目前学界尚未探究这两类胁迫因子对传粉者学习与记忆功能的潜在交互影响。此外，不同物种对胁迫因子的敏感性可能存在差异，但目前鲜有研究比较不同蜂类的响应模式。本研究发现，长期暴露于田间实测浓度的新烟碱类（neonicotinoid）杀虫剂噻虫胺（clothianidin），会损害蜜蜂的嗅觉学习习得能力，进而可能对蜂群适合度造成负面影响，但对熊蜂并无此效应。蜜蜂感染微孢子虫（microsporidian parasite）寄生菌蜂微孢子虫（Nosema ceranae）后，其学习能力会出现轻微受损，但未观察到交互效应。蜂微孢子虫未能成功感染熊蜂，感染成功率仅为3%。不过，经蜂微孢子虫处理的熊蜂，其学习速率较对照组略低，但当同时暴露于新烟碱类杀虫剂时，其学习速率反而更快。这一结果凸显了胁迫因子对学习功能存在复杂交互影响的可能性。本研究结果表明，无法直接将某一蜂种的研究结论外推至其他蜂类，这对于以蜜蜂作为所有蜂类模型的监管风险评估工作，具有重要的指导意义。