Monday, December 22, 2008

Another Benefit of Pollinators in the Garden?

In an article published in the journal Current Biology, researchers from the University of Wurzburg in Germany report that the presence of honey bees deters damage by plant feeding caterpillars. Tautz and Rostas measured plant damage to soybeans and peppers (with and without fruit) by beet armyworms, in the presence and absence of honey bees. When the plants were not fruiting, the presence of honey bees reduced caterpillar damage by 61-69%, compared to plants with the beet armyworms but without the honey bees.

The scientists suggest that damage is reduced, because the caterpillars sense vibrations by the bees' wings. In an earlier study, Tautz and Markl found that caterpillars use hairs on their body to sense the vibrations of hunting wasps. When wasps are perceived, the caterpillars stop moving, stop feeding, and vomit. This reaction delivers a degree of protection to the caterpillars - those exhibiting these behaviors are attacked 30% less than caterpillars that continue to feed.

The recent Tautz and Rostas study is exciting, because it suggests another potential benefit of pollinators in the garden. In addition, this study provides a new perspective on interactions between plants, herbivores and pollinators. Scientists have long known that herbivore damage can reduce the attractiveness of flowering plants to pollinators. But, this is the first study that I know of that suggests that pollinators can have a similar effect on herbivores.

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