Physiological control of pheromone production in Choristoneura fumiferana and C. rosaceana

摘要

The diel periodicity of calling behaviour and pheromone production are synchronous in virgin females of both Choristoneura fumiferana and C. rosaceana (Lepidoptera: Tortricidae). Newly emerged females decapitated prior to scotophase produced no or very little pheromone 24 h later. However, injection of PBAN or Br-SEG homogenates, obtained from donors of the same or the other species, stimulated pheromone production to normal levels. Transection of the ventral nerve cord (VNC) or extirpation of theterminal abdominal ganglion (TAG) did not affect pheromone production in control females. Similarly, injections of PBAN or Br-SEG homogenates into decapitated females reactivated pheromone production to normal levels, whether or not the VNC was intact orthe TAG present. Furthermore, octopamine was not effective in stimulating pheromone production in decapitated females. Taken together, these results indicate that the regulation of pheromone production is not neurally mediated in either Choristoneura species. However, there was no evidence that haemolymph collected from pheromone-producing females contained pheromonotropic activity. Similarly, isolated glands incubated with PBAN did not produce pheromone. The presence of the bursa copulatrix was required to produce pheromone in both tortricids as production was not restored in decapitated bursa-less females injected with PBAN or a Br-SEG homogenate. However, an extract of the bursa copulatrix did not elicit pheromonotropic activity in decapitated females or incubated glands of either species. The bursa copulatrix is only involved in pheromone production of some species of tortricids but the results do not support the current explanation for such interspecific differences. It is postulated that the relative importance of a bursa factor may be related to the evolution of different desaturation systems used for pheromome biosynthesis in the Tortricidae.