Posted by: Dave DeWitt on Jan 02, 2009
German researchers have discovered that the flapping of bees' wings scares off caterpillars, reducing leaf damage on bell peppers and soybeans.
Many wasp species lay their eggs in caterpillars, and so caterpillars have evolved to avoid them. The sounds of bees' and wasps' wings are similar.
Researchers suggest this is an added bonus of having bees around, as well as the pollination they provide.
The scientists wrote in the journal Current Biology: "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."
For the experiment, researchers used bell pepper and soybean plants, beet armyworm caterpillars, and honeybees. They set up experimental plots of the plants, added the caterpillars, and allowed the bees to enter some of the plots but not others.
When the caterpillars had turned into pupae and buried away in the soil, the scientists went back into the cages and measured the extent of leaf damage - the amount of munching that the caterpillars had indulged in.
The presence of bees reduced caterpillar damage by about 60% in plants that had not fruited.