Spiders leave silk in their wake, and the researchers speculated that the strands “may serve as a general warning signal.” The team decided to test their idea on Japanese beetles and Mexican bean beetles, which web-building spiders like to eat.
In a field at Miami University, the researchers placed strands of spider or silkworm silk on the leaflets of snap beans. They also added silk to bean leaflets in the lab. Then the team allowed beetles to munch the plants and measured how much the insects had eaten.
In the lab, the beetles chewed off part of the untreated leaflets but left the leaflets with silk undamaged. And in the field, the spider silk-treated leaflets showed almost 40 percent less damage than the leaflets without silk.
The beetles appeared to recognize the silk as a sign of a predator and ate less in response, suggesting that spider silk could reduce pest damage to crops. “Silk has many remarkable properties,” the authors write, and “these results add plant protection to the list.” — Roberta Kwok | 29 November 2012
Source: Rypstra, A.L. and C.M. Buddle. 2012. Spider silk reduces insect herbivory. Biology Letters doi: 10.1098/rsbl.2012.0948.
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