COTTON VOLATILES SYNTHESIZED AND RELEASED DISTAL TO THE SITE OF INSECT DAMAGE

Cotton plants (Gossypium hirsutum) damaged by herbivorous insects rele ase volatile compounds that act as chemical signals to attract natural enemies of the herbivore to the damaged plant. Feeding by beet armywo rm larvae (Spodoptera exigua) on the lower leaves of cotton plants tri ggers the systemic release of six readily detectable terpenes and hexe nyl acetate, a product of the lipoxygenase pathway. Labelling with (CO 2)-C-13 established that the terpenes released systemically after herb ivore damage are synthesized de novo at or near the site of emission. Hexenyl acetate rapidly incorporated C-13 into the acetate but not int o the hexenyl moiety within our pulse labelling interval. Thus, activa tion of the lipoxygenase pathway in undamaged leaves of insect damaged plants is indicated. (C) 1997 Elsevier Science Ltd. All rights reserv ed.