The "Raison D'être" of pyrrolizidine alkaloids inCynoglossum officinale: Deterrent effects against generalist herbivores.

In this study we tested whether pyrrolizidine alkaloids (PAs) ofCynoglossum officinale serve as antifeedants against herbivores. Total PA N-oxide extracts of the leaves significantly deterred feeding by generalist herbivores. Specialist herbivores did not discriminate between food with high and low PA levels.