AbstractHormonal control of the production of the main sex pheromone component, Z11‐hexadecenal (Z11‐16:Ald), of femaleHelicoverpa zeawas investigated using labeled precursors to monitor the pheromone biosynthetic pathway. The pathway originates with the biosynthesis of palmitic acid followed by δ11 desaturation to form the intermediate Z11‐16:Acid, which is then reduced to a primary alcohol and then oxidized to Z11‐16:Ald. Incubation of glands either in vivo or in an isolated gland culture with the deuterium labeled compounds, D3‐16:Acid or D9‐Z11‐16:Acid, yielded no differences in label incorporation into pheromone in the presence or absence of synthetic PBAN (Pheromone biosynthesis activity neuropeptide). However, unlabeled pheromone titers increased about tenfold above controls in the presence of PBAN in both in vivo and in vitro cultures. When isolated glands were incubated with [1‐14C]acetate, about a thirtyfold increase in the incorporation of radiolabel into Z11‐16:Ald above controls was observed in the presence of PBAN. Also, about a tenfold increase in incorporation was observed in saturated and monounstaturated fatty acids found in the gland upon stimulation with PBAN. These results indicate that the hormone PBAN controls pheromone biosynthesis inH. zeaby regulating a step in or prior to fatty