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Bees Prefer Nicotine and Caffeine in Nectar

Bees prefer nectar with small amounts of nicotine and caffeine over nectar that does not contain these substances at all, according to results of a recent study from the University of Haifa in Israel. “This could be an evolutionary development intended, as in humans, to make the bee addicted,” stated Dr. Ido Izhaki, one of the researchers who conducted the study. The researchers emphasized, however, that their study has proved a preference, not an addiction, and they are currently conducting additional studies to determine if bees do indeed become addicted to nicotine and caffeine. Flower nectar is primarily composed of sugars, which provide energy for the potential pollinators. But the floral nectar of some plant species also includes small quantities of substances known to be toxic, such as caffeine and nicotine. Nicotine is found naturally in floral nectar at a concentration of up to 2.5 milligrams per liter, primarily in various types of tobacco trees. Caffeine is found at concentration levels of 11-17.5 milligrams per liter, mostly in citrus flowers. In the nectar of grapefruit flowers, however, caffeine is present in much higher concentrations, reaching 94.2 milligrams per liter. In order to examine whether bees prefer the nectar containing caffeine and nicotine, the researchers offered artificial nectar that contained various natural sugar levels and various levels of caffeine and nicotine, alongside “clean” nectar that included sugar alone. The caffeine and nicotine concentrations ranged from the natural levels in floral nectar up to much higher concentrations than found in nature. The results showed that bees clearly prefer nectar containing nicotine and caffeine over the “clean” nectar. The preferred nicotine concentration was 1 milligram per liter, similar to that found in nature. Given a choice of higher levels of nicotine versus “clean” nectar, the bees preferred the latter. This work was reported in a press release from the University of Haifa. [University of Haifa press release]