May 23, 2013 — Plants have many strategies for manipulating animals to do their bidding. Some flowers focus the attention of their pollinators with a familiar pick-me-up--caffeine. Martha Foley and Dr. Curt Stager discuss the natural world.
Summary of this Natural Selections conversation:
Bees and other pollinators are attracted to both the colors and smells of flowers. The pollen that flowers produce will stick to the bees and will ultimately be transferred to the next plant the bee visits. And the bees get nectar for food. So the process is mutually beneficial.
However, another layer of this story was recently published in the Journal Science by researchers from both the United Kingdom and the United States. According to Dr. Curt Stager of Paul Smith’s College, it appears that, “Some flowers manipulate the minds (or the brains) of the insects that come to them to make them more memorable.”
It turns out that bees are as susceptible as humans to the allure of caffeine. Most plants that produce caffeine use its bitter taste to repel other creatures from eating them, but some plants, including different species of coffee trees and citrus fruits, deposit a little bit of caffeine in their nectar.
Researchers tested how this works by studying the activity of bees around a variety of flowers, only some of which contained caffeine in the nectar. Later, researchers measured how many bees returned to which blossoms. They found that the bees were more likely to remember the caffeinated flowers.
Stager says that the caffeine “enhances their memory, which would be beneficial of course to the bees, because it makes their foraging easier and more efficient.” And if the bee repeatedly returns to the same type of flower, then the flower will be more widely pollinated, to its benefit.
The researchers used a controlled population to measure how many times the bees visited each kind of flower, with or without the caffeine. Then they measured the neurons of the bees, and discovered that the caffeine stimulated the neurons in the insect’s brains associated with memory. Stager concludes, “When you smell your nice flower and get your reward, it’s a more intense experience and the experience becomes more memorable.”