Tannins in plant-herbivore interactions

► Tannins have diverse effects on herbivores. ► In insect guts, tannins may act as prooxidants rather than binding proteins. Insects have physiological and structural defenses and can tolerate tannins. ► Tannin effects in vertebrates may be both positive and negative and do involve protein binding. ► In the future, molecular biology tools will help define the ecological roles of tannins.