1. Caffeine in floral nectar enhances a pollinator's memory of reward.
- Author
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Wright GA, Baker DD, Palmer MJ, Stabler D, Mustard JA, Power EF, Borland AM, and Stevenson PC
- Subjects
- Animals, Bees physiology, Caffeine analysis, Citrus chemistry, Coffea chemistry, Flowers chemistry, Flowers physiology, Mushroom Bodies drug effects, Mushroom Bodies physiology, Plant Nectar chemistry, Pollination physiology, Reward, Taste drug effects, Bees drug effects, Behavior, Animal drug effects, Caffeine pharmacology, Citrus physiology, Coffea physiology, Memory drug effects, Plant Nectar physiology, Pollination drug effects
- Abstract
Plant defense compounds occur in floral nectar, but their ecological role is not well understood. We provide evidence that plant compounds pharmacologically alter pollinator behavior by enhancing their memory of reward. Honeybees rewarded with caffeine, which occurs naturally in nectar of Coffea and Citrus species, were three times as likely to remember a learned floral scent as were honeybees rewarded with sucrose alone. Caffeine potentiated responses of mushroom body neurons involved in olfactory learning and memory by acting as an adenosine receptor antagonist. Caffeine concentrations in nectar did not exceed the bees' bitter taste threshold, implying that pollinators impose selection for nectar that is pharmacologically active but not repellent. By using a drug to enhance memories of reward, plants secure pollinator fidelity and improve reproductive success.
- Published
- 2013
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