Arnold Sarah E J, Dudenhöffer Jan-Hendrik, Fountain Michelle T, James Katie L, Hall David R, Farman Dudley I, Wäckers Felix L, Stevenson Philip C
Natural Resources Institute, University of Greenwich, Chatham Maritime, Kent ME4 4TB, UK; Nelson Mandela African Institution of Science and Technology, Arusha, Tanzania.
Natural Resources Institute, University of Greenwich, Chatham Maritime, Kent ME4 4TB, UK.
Curr Biol. 2021 Sep 27;31(18):4127-4131.e4. doi: 10.1016/j.cub.2021.06.068. Epub 2021 Jul 28.
Caffeine is a widely occurring plant defense chemical that occurs in the nectar of some plants, e.g., Coffea or Citrus spp., where it may influence pollinator behavior to enhance pollination. Honey bees fed caffeine form longer lasting olfactory memory associations, which could give plants with caffeinated nectar an adaptive advantage by inducing more visits to flowers. Caffeinated free-flying bees show enhanced learning performance and are more likely to revisit a caffeinated target feeder or artificial flower, although it is not clear whether improved memory of the target cues or the perception of caffeine as a reward is the cause. Here, we show that inexperienced bumble bees (Bombus terrestris) locate new food sources emitting a learned floral odor more consistently if they have been fed caffeine. In laboratory arena tests, we fed bees a caffeinated food alongside a floral odor blend (priming) and then used robotic experimental flowers to disentangle the effects of caffeine improving memory for learned food-associated cues versus caffeine as a reward. Inexperienced bees primed with caffeine made more initial visits to target robotic flowers emitting the target odor compared to control bees or those primed with odor alone. Caffeine-primed bees tended to improve their floral handling time faster. Although the effects of caffeine were short lived, we show that food-locating behaviors in free-flying bumble bees can be enhanced by caffeine provided in the nest. Consequently, there is potential to redesign commercial colonies to enhance bees' forage focus or even bias bees to forage on a specific crop.
咖啡因是一种广泛存在的植物防御性化学物质，存在于某些植物的花蜜中，例如咖啡属或柑橘属植物，在这些植物中它可能会影响传粉者行为以增强授粉。摄入咖啡因的蜜蜂会形成持续时间更长的嗅觉记忆关联，这可能会使花蜜中含有咖啡因的植物具有适应性优势，因为这会促使蜜蜂更多地访问花朵。自由飞行且摄入咖啡因的蜜蜂表现出更强的学习能力，并且更有可能再次访问提供含咖啡因食物的目标喂食器或人造花朵，不过目前尚不清楚是对目标线索的记忆改善还是将咖啡因视为奖励的认知导致了这种情况。在这里，我们表明，如果给没有经验的熊蜂（熊蜂）喂食咖啡因，它们会更一致地找到散发着已学会花香气味的新食物来源。在实验室场地测试中，我们给蜜蜂喂食含咖啡因的食物并搭配花香气味混合物（启动），然后使用机器人实验花朵来区分咖啡因改善对已学会的与食物相关线索的记忆的效果与咖啡因作为奖励所产生的效果。与对照蜜蜂或仅用气味启动的蜜蜂相比，用咖啡因启动的没有经验的蜜蜂对散发目标气味的目标机器人花朵进行的首次访问更多。用咖啡因启动的蜜蜂往往能更快地提高它们处理花朵的时间。尽管咖啡因的效果持续时间较短，但我们表明，蜂巢中提供的咖啡因可以增强自由飞行的熊蜂寻找食物的行为。因此，有可能重新设计商业蜂群，以增强蜜蜂对觅食的专注度，甚至引导蜜蜂专门为特定作物觅食。
