Signal honesty through differential quantity in the female-produced sex pheromone of the moth Heliothis virescens.

Over the last 50 years, female-produced sex pheromones of moths have been subjected to intensive study. Most work has focused on their role in mate recognition, and little on any role they may have in mate assessment. This is largely because it has been assumed that female, rather than male, moths are "choosy", and invest larger amounts of carbon in eggs than in pheromone. Recently, we found that pheromone production in the moth Heliothis virescens depended on hemolymph trehalose concentration, and that sugar-stressed females produced less pheromone than unstressed ones. In this paper, we demonstrate, for the first time in moths, that a female-produced pheromone signal can allow H. virescens males to assess sugar resources (quality) of a female. This signal honesty is based on quantitative, rather than qualitative (component ratio), differences in pheromone, produced and released by sugar-stressed and unstressed females. Increasing marginal cost of pheromone production, as sugar resources are depleted, may ensure signal honesty.