Honeybees might deserve the title of the farmer’s best friend: A new study shows that not only do the busy insects pollinate flowers and make honey, they also scare away agricultural pests that like to chomp on the leaves of crop plants. Said the study’s coauthors: “Our findings indicate for the first time that visiting honeybees provide plants with a totally unexpected advantage…. They not only transport pollen from flower to flower, but in addition also reduce plant destruction by herbivores” [BBC News].
The bees act as inadvertent protectors of plants, researchers say. Caterpillars are constantly on the lookout for wasps, one of their main predators, and have delicate sensory hairs on their bodies that detect the air currents caused by a wasp’s beating wings. “These sensory hairs are not fine-tuned,” said [study coauthor] Jurgen Tautz…. “Therefore, caterpillars cannot distinguish between hunting wasps and harmless bees.” If an insect which they cannot identify generates air vibrations the caterpillars stop moving or drop away from the plant [Telegraph].
In the study, published in Current Biology [subscription required], researchers set up rows of bell pepper plants inside of enclosed tents. They then placed about 10 beet armyworm caterpillars (Spodoptera exigua), a notorious crop pest, on each plant. One tent had a window connected to a beehive, and feeders filled with a sugar solution attracted bees inside. The second tent was closed to the outside world. After about 2 weeks, [the researchers] collected the leaves from the bell pepper plants [ScienceNOW Daily News]. They found that the plants grown in the tent with bees suffered about 60 percent less leaf damage than the other plants.
The researchers say their findings offer yet another reason to be worried about the decline of bee populations due the mysterious syndrome known only as colony collapse disorder, as the experiment shows another subtle benefit that bees bring to agriculture. Tautz says he can imagine that gardeners might someday take advantage of this effect. “Alternating rows of vegetables and flowers not only look beautiful, they may reduce the use of pesticides,” he says [Science News].
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Image: flickr / cygnus921