CONCERTED BIOSYNTHESIS OF AN INSECT ELICITOR OF PLANT VOLATILES

A variety of agricultural plant species, including corn, respond to in sect herbivore damage by releasing large quantities of volatile compou nds and, as a result, become highly attractive to parasitic wasps that attack the herbivores. An elicitor of plant volatiles, N-(17-hydroxyl inolenoyl)-L-glutamine, named volicitin and isolated from beet armywor m caterpillars, is a key component in plant recognition of damage from insect herbivory. Chemical analysis of the oral secretion from beet a rmyworms that have fed on C-13-labeled corn seedlings established that the fatty acid portion of volicitin is plant derived whereas the 17-h ydroxylation reaction and the conjugation with glutamine are carried o ut by the caterpillar by using glutamine of insect origin, Ironically, these insect-catalyzed chemical modifications to linolenic acid are c ritical for the biological activity that triggers the release of plant volatiles, which in turn attract natural enemies of the caterpillar.