HR11 and HR13 Receptor-Expressing Neurons Are Housed Together in Pheromone-Responsive Sensilla Trichodea of Male Heliothis virescens

The highly specific recognition of female-released sex pheromones in insects by sensory neurons of the male antenna requires specific receptors. Recently, a small family of related candidate pheromone receptors has been identified for a few moth species. In this study, the candidate pheromone receptor HR11 from Heliothis virescens has been characterized. HR11 was found to be expressed in numerous cells located in short and long sensilla trichodea on the male antenna. The HR11 cells are stereotypically arranged in a paired pattern together with HR13 cells, which respond to the major component of the sex pheromone blend. Triple in situ hybridization approaches revealed that each pair of an HR11 cell and an HR13 cell was ensheathed by supporting cells, which express pheromone-binding proteins, thus constituting a structural unit. The paired pattern of HR11/HR13 cells is reminiscent of the pattern described for BmOR-1- and BmOR-3-expressing cells in the antenna of Bombyx mori, which respond to bombykol and bombykal, respectively. These results suggest that the ligand for HR11 may be related to the HR13 ligand and furthermore imply that an arrangement of cells expressing related receptor types in the same sensillum may be a general principle in moth pheromone detection systems.