Argentine ants Linepithema humile are one of the most damaging invasive alien species worldwide. Enhancing or disrupting cognitive abilities, such as learning, has the potential to improve management efforts, for example by increasing preference for a bait, or improving ants’ ability to learn its characteristics or location. Nectar-feeding insects are often the victims of psychoactive manipulation, with plants lacing their nectar with secondary metabolites such as alkaloids and non-protein amino acids which often alter learning, foraging, or recruitment. However, the effect of neuroactive chemicals has seldomly been explored in ants. Here, we test the effects of seven potential neuroactive chemicals - two alkaloids: caffeine and nicotine; two biogenic amines: dopamine and octopamine, and three non-protein amino acids: β-alanine, GABA and taurine - on the cognitive abilities of invasive L. humile using bifurcation mazes. Our results confirm that these ants are strong associative learners, requiring as little as one experience to develop an association. However, we show no short-term effect of any of the chemicals tested on spatial learning, and in addition no effect of caffeine on short-term olfactory learning. This lack of effect is surprising, given the extensive reports of the tested chemicals affecting learning and foraging in bees. This mismatch could be due to the heavy bias towards bees in the literature, a positive result publication bias, or differences in methodology.

中文翻译：

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侵入式蚂蚁学习不受七种潜在神经活性化学物质的影响

阿根廷蚂蚁 Linepithema humile 是世界上最具破坏性的外来入侵物种之一。增强或破坏认知能力（例如学习）有可能改善管理工作，例如通过增加对诱饵的偏好，或提高蚂蚁了解其特征或位置的能力。以花蜜为食的昆虫通常是精神操纵的受害者，植物将花蜜与次级代谢产物（例如生物碱和非蛋白质氨基酸）结合起来，这些次级代谢产物通常会改变学习、觅食或招募。然而，很少在蚂蚁中探索神经活性化学物质的作用。在这里，我们测试了七种潜在的神经活性化学物质的影响——两种生物碱：咖啡因和尼古丁；两种生物胺：多巴胺和章鱼胺，以及三种非蛋白质氨基酸：β-丙氨酸，GABA 和牛磺酸 - 使用分叉迷宫对侵入性 L. humile 的认知能力。我们的结果证实，这些蚂蚁是很强的联想学习者，只需要一次经验就可以建立关联。然而，我们没有显示任何化学物质对空间学习的短期影响，此外咖啡因对短期嗅觉学习也没有影响。考虑到影响蜜蜂学习和觅食的受试化学物质的大量报告，这种效果的缺乏令人惊讶。这种不匹配可能是由于文献中对蜜蜂的严重偏见、积极的结果发表偏见或方法上的差异。只需要一次经验就可以建立一个协会。然而，我们没有显示任何化学物质对空间学习的短期影响，此外咖啡因对短期嗅觉学习也没有影响。考虑到影响蜜蜂学习和觅食的受试化学物质的大量报告，这种效果的缺乏令人惊讶。这种不匹配可能是由于文献中对蜜蜂的严重偏见、积极的结果发表偏见或方法上的差异。只需要一次经验就可以建立一个协会。然而，我们没有显示任何化学物质对空间学习的短期影响，此外咖啡因对短期嗅觉学习也没有影响。考虑到影响蜜蜂学习和觅食的受试化学物质的大量报告，这种效果的缺乏令人惊讶。这种不匹配可能是由于文献中对蜜蜂的严重偏见、积极的结果发表偏见或方法上的差异。