Metro Atlanta Beekeepers Association |
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Henry Fountain, New York Times, August 15, 2006 Shivering works to warm the body up on a cold day. But a hot drink can help, too -- the more heat from the drink, the less shivering necessary. What works for people works for bees as well, researchers in England have found. Given a choice, bumblebees will choose a warmer flower, with its warmer nectar, over a cooler one. What's more, the bees learn to identify warmer flowers by their color. Bumblebees need to warm themselves up in order to fly, said Lars Chittka of Queen Mary College at the University of London, an author of a brief paper describing the research in the Aug. 3 issue of Nature. Typically, bumblebees need a body temperature of close to 100 degrees Fahrenheit. To reach that temperature in cold weather takes a lot of energy. Like people, bees warm up by shivering, but they'll take help when they can get it. Dr. Chittka said many plant species have an adaptation in the surfaces of their flowers: conelike cells that focus sunlight on the floral pigments underneath. This makes them warmer than species without the adaptation. ''We were interested in the question of whether bees take this into account,'' he said. ''Whether they opt for warmer flowers or nectar.'' The researchers experimented using artificial flowers of various temperatures (artificial flowers enabled them to eliminate other possible factors, like petal texture, that might influence bee behavior). They found that bees preferred to feed at warmer flowers, even if they were as little as 7 degrees warmer than those at ambient temperature. In another experiment with artificial flowers of different colors and different temperatures, the researchers found that bees quickly learned to associate warmth with color. ''They needed to land on the flower and experience the warmer temperature,'' Dr. Chittka said, but once they did, they regularly chose flowers of that color. The bees benefit, of course, but so do the flowers, by having more bees pollinate them. The adaptation that makes the flowers warmer is another example of evolution at work, Dr. Chittka said. ''Flower species are engaged in a competitive race with other flower species,'' he said, and do many things to attract and keep pollinators, like making big showy flowers. ''But also in this competitive race, they might benefit by offering them warmer drinks.''
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