Buzz off, caterpillars! - December 23, 2008
Buzzing bees protect plants from pesky caterpillars, providing yet another example of the intricate and often unexpected linkages that make up food webs.
Leaf-eating caterpillars are the bane of gardeners and farmers. However, while these pesty predators search for tasty plants, they are hunted by carnivorous wasps. Consequently, caterpillars keep bristling sensory hairs alert for attacks from above and drop to the ground when they sense danger.
Biologist Jurgen Tautz of Biozentrum University in Bavaria, Germany, realized that the caterpillars' defence mechanism was not “fine-tuned" and suspected that “caterpillars cannot distinguish between hunting wasps and harmless bees." Thus, Tautz wondered whether bees might affect pest foraging behaviour (press release).
As reported in Current Biology, Tautz and his colleague Michael Rostas set up small tents that contained pepper and soya plants and voracious beet armyworm caterpillars. Unsurprisingly, the insects climbed the plants and devoured the foliage. When bees were introduced into the tents, however, the caterpillars stayed grounded, and hungry.
These findings, says Tautz in the press release, show “for the first time” that visiting honeybees provide plants with an unexpected advantage — protection.
"While the study was small, the results were convincing," ecologist Thomas Ings of the University of London, Queen Mary, told ScienceNOW.
Tautz hopes that gardeners might be able to take advantage of this effect. He suggests, for example, that by planting vegetables and flowers in alternating rows, green thumbs can keep bee traffic up, which may protect foliage and reduce the need for pesticides.
Top image: PLoS Biol 2/8/2004: e250. http://dx.doi.org/10.1371/journal.pbio.0020250
