The effect of the juvenile hormone analog, fenoxycarb on the PBAN-receptor and pheromone production in adults of the moth Helicoverpa armigera: an “aging” hormone in adult females?

In a previous study we showed that juvenile hormone (JH) or its analog, fenoxycarb (FX), is involved in the up-regulation of pheromone biosynthesis-activating neuropeptide (PBAN) competence. JH causes induction of binding to a putative PBAN-receptor (PBAN-R) and the subsequent pheromone production by pheromone glands of pharate females. The present study demonstrates that pheromone production by the adult female is age-dependent. The pheromonotropic response increased to reach a maximum at 4 days, after which a decreased response was observed. Binding of the PBAN-R was also age-dependent. Treatment with FX inhibited both binding of PBAN to the PBAN-R and the pheromonotropic response as reflected by the production of the main pheromone component, Z-11-hexadecenal. Thus, in contrast to its up-regulatory role in pharate females, FX treatment of adult females causes down-regulation of both pheromone production and specific binding to the PBAN-R. In addition, behavioural observations showed that calling behaviour, mating success and subsequent egg-fertility are affected by treating females with FX.