Male accessory gland factors increased sex pheromone titres in the glands of Spodoptera litura female moths by inhibiting calling behavior

Moths are the most widely studied example of pheromones in animals. However, little is known about the mechanism of intrasexual and mating-related intersexual regulation of pheromone production and release in female moths. Our previous studies in Spodoptera litura found that mating induced a higher sex pheromone titre in the pheromone gland (PG) and mating or male accessory gland (MAG) extract suppressed female calling behavior. We therefore hypothesize that the inhibition of female calling behavior by mating or MAG factors likely suppresses the release of sex pheromones and thus results in a higher pheromone titre in the PG. To test this hypothesis, in the present study, we introduced an artificial calling behavior suppression treatment by gently knocking on and shaking the testing boxes contained moths once every 10 minutes. Results show that this treatment significantly increased pheromone titres in virgin or saline injected virgin females, and the increase rates are similar to those of mating and MAG extract treated ones. These results have suggested that the increase of sex pheromone titer in the female PG after mating in S. litura is due to the inhibition of female calling behavior by MAG factors. Moreover, results of this study also suggest that female calling behavior is positively correlated to pheromone release and likewise, the calling behavior and sex pheromone release in S. litura females are directly under the neural control, and modulated by molecular and environmental factors.