Submitted to: Journal of Comparative Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/26/2003
Publication Date: 2/1/2004
Citation: Baker, T.C., Ochieng, S.A., Cosse, A.A., Lee, S.C., Todd, J.L., Quero, C., Vickers, N.J. 2004. Comparative responses of the olfactory receptor neurons of Heliothis subflexa and Heliothis virescens to their sex pheromone components. Journal of Comparative Physiology. 190:155-165. Interpretive Summary: Much work has been performed during the last three decades on the sex pheromones (species-specific attractant) of moths. These sex pheromones are being used as environmentally friendly control agents for the control and detection of pest insects. The majority of sex pheromones from moth species are blends of volatile chemicals and some of the components in these blends are shared by more than one, and often related, species. The current study reports the results on how receptors on the antennae of two such related species, one of which is an important agricultural pest in the US, are distinguishing their sex pheromone signals as their own. These fundamental neurophysiological results help to define the underlying processes of pheromone detection and might be beneficial to future pheromone control strategies.
Technical Abstract: Single-cell electrophysiological recordings were obtained from olfactory receptor neurons (ORNs) in sensilla trichodea on male antennae of the heliothine species. Heliothis subflexa and the closely related congener Heliothis virescens. A large percentage of sensilla (72 and 81% respectively of all sensilla sampled) contained a single odor-responsive ORN tuned to the major pheromone component of both species, Z-11-hexadecenal (Z11-16:Ald). A second population of sensilla on H. subflexa antennae (18%) housed ORNs that were tuned to Z-9-hexadecenal (Z9-16:Ald), an essential component of the pheromone blend in this species. These ORNs also responded to Z-9-tetradecenal (Z9-14:Ald) but were less sensitive to this compound. A similar population of sensilla (4%) on H. virescens male antennae housed ORNs that were shown to be tuned specifically only to the essential H. virescens secondary sex pheromone component, Z-9-14:Ald, with no response to even high dosages of Z9-16:Ald. A third population of sensilla (comprising 8 and 16% of the sensilla sampled in H. subflexa and H. virescens, respectively) housed two ORNs, one of which was tuned to Z-11-hexadecenyl acetate (Z11-16:Ac) and the other tuned to Z-11-hexadecenol (Z11-16:OH). In H. subflexa the Z11-16:Ac-tuned ORN also responded to Z9-14:Ald with nearly equivalent sensitivity, whereas in H. virescens it was the Z11-16:OH-tuned ORN that responded to Z9-14:Ald, but only weakly and only at very high emitted dosages. These results help to explain the requirement of these two species for distinct pheromonal blends.