Air Date: Week of July 19, 2002

Living on Earth’s Maggie Villiger reports on research that wood rats use bay leaves to keep their homes pest-free.

Transcript

TOOMEY: Just ahead, in Zambia, orphaned and abused chimpanzees find refuge in the arms of a 70 year old grandmother. First, this page from the Animal Notebook with Maggie Villiger.

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VILLIGER: Having a home infested with pests isn’t fun for anyone, including dusky-footed wood rats. But these rodent natives of California are doing something about their parasite invasion. Wood rats, also known as pack rats, live in above-ground stick houses, complete with distinct sleeping areas. They furnish their abodes with fresh green foliage which biologists assumed was stored by the rodents to be eaten later.

But recently, researchers noticed that wood rats were tucking carefully nibbled bay leaves into their sleeping nests. And bay isn’t a typical food for the wood rats. But bay trees do produce essential oils that discourage insects from eating their leaves. So scientists guessed the wood rats were harnessing these insecticidal properties and using bay leaves to fumigate their bedrooms.

Back in the lab, researchers exposed flea larvae to torn bay, oak or toyon leaves. They found that flea survival rates dropped 60 to 70% in the bay leaf container compared to the other leaves. Scientists know birds incorporate anti-pest plants into their nests, but this is the first time the behavior has been seen in mammals. That’s this week’s Animal Note. I’m Maggie Villiger.

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TOOMEY: And you’re listening to Living on Earth.

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