REGULATION OF SEX-PHEROMONE BIOSYNTHESIS IN THE ORIENTAL TOBACCO BUDWORM, HELICOVERPA-ASSULTA (LEPIDOPTERA, NOCTUIDAE)

The five components, Z9-16:Ald, 16:Ald, Z11-16:Ald, Z9-16:Ac and Z11-1 6:Ac, of the sex pheromone in Helicoverpa assulta were mostly detected during the scotophase, with their titer peaking at the 4th hour durin g the scotophase under a 15L/9D regime. They were not detected during the photophase, but were produced during the photophase when decapitat ed females were injected with extracts of virgin female (FHE), male he ads (MHE), homogenates of the brain-suboesophageal ganglion complex (B r-SOG), or synthetic Hez-PBAN. Production of Z9-16:Ald increased durin g the first 45 min after FHE injection and then declined to a very low level after 2 h during the photophase. Synthetic Hez-PBAN stimulated the sex pheromone glands for at least 2 h and the effect was more or l ess proportional to the concentration of the peptide. From the present results, we suggest the following: PBAN is released continuously into the haemolymph to stimulate pheromone biosynthesis at least during th e first half of the scotophase, PBAN is synthesized and accumulated in dependent of photoperiod or sex and the release starts just prior (abo ut 1 h) to the beginning of the scotophase. (C) 1998 Elsevier Science Ltd. All rights reserved.