ANTINUTRITIVE AND TOXIC COMPONENTS OF PLANT DEFENSE AGAINST INSECTS

Chemical defense of the tomato plant against noctuid larvae is argued to result from suites of interactive chemical traits that simultaneous ly impair the acquisition of nutrients and toxify the insect. Defense results from tomatine, catecholic phenolics and phenol oxidases, prote inase inhibitors, and lipoxygenase. The catalytic role of plant oxidat ive enzymes in activating a variety of defense mechanisms is discussed . It is argued that the terms ''digestibility reducer,'' ''toxin,'' an d ''nutrient'' signify ecological outcomes, not properties of molecule s. Current views on the roles and the modes of activity of plant natur al products against herbivorous insects are challenged. It is proposed that chemical context and mixture are critical determinants of biolog ical activity, and that viewing natural products as isolated defensive factors is often misleading. (C) 1996 Wiley-Liss, Inc.