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find that certain mushrooms, when bitten by slugs, synthesize a slug repellent that drives them off. The work started when the people involved were collecting wild mushrooms in the coastal rain forests of the Pacific Northwest. They noticed that some mushrooms had small bite marks on their caps, as if they had been tasted and rejected by the giant banana slug (Ariolimax columbianus). They followed up with research on the sweetbread mushroom (Clitopilus prunulus), having observed slugs tasting this species and quickly turning to others. The sweetbread mushroom, say author, is a highly edible species found in North America and Europe. People usually cook it before eating it. The authors found that rupturing the tissue of the mushroom, as munching slugs would do, releases the slug repellent 1-octen-3-ol. Comparison of volatile chemicals in crushed and uncrushed mushrooms showed that crushing increased the level of the volatile repellent 19-fold. In the laboratory, banana slugs refused to eat lettuce treated with similar amounts of the repellent. To humans, say author 1-octen-3-ol smells like a typical mushroom. The compound has been identified in many species of mushrooms (but not the one commonly eaten by banana slugs), so its slug antifeedant activity may be widespread in nature. Mushrooms synthesize the chemical from linoleic acid. The compound has been shown to have antibacterial as well as antislug activity, the authors say, and so may protect mushrooms from microbes trying to invade a slug-inflicted wound.
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