A comparison of responses from olfactory receptor neurons of Heliothis subflexa and Heliothis virescens to components of their sex pheromone

Abstract

Single-cell electrophysiological recordings were obtained from olfactory receptor neurons in sensilla trichodea on male antennae of the heliothine species Heliothis subflexa and the closely related congener H. virescens. A large percentage of sensilla (72% and 81%, respectively, of all sensilla sampled) contained a single odor-responsive receptor neuron tuned to the major pheromone component of both species, Z-11-hexadecenal. A second population of sensilla on H. subflexa antennae (18%) housed receptor neurons that were tuned to Z-9-hexadecenal but also responded with less sensitivity to Z-9-tetradecenal. A similar population of sensilla (4%) on H. virescens male antennae housed receptor neurons that were shown to be tuned specifically only to Z-9-tetradecenal, with no response to even high dosages of Z-9-hexadecenal. A third population of sensilla (comprising 8% and 16% of the sensilla sampled in H. subflexa and H. virescens, respectively) housed two olfactory receptor neurons, one of which was tuned to Z-11-hexadecenyl acetate and the other tuned to Z-11-hexadecenol. In H. subflexa the Z-11-hexadecenyl acetate-tuned neuron also responded to Z-9-tetradecenal with nearly equivalent sensitivity. The behavioral requirements of males of these two species for distinct pheromonal blends was, therefore, reflected by the subtle differences in the tuning properties of antennal olfactory receptor neurons.

Sexual isolation of male moths explained by a single pheromone response QTL containing four receptor genes

“…We compared the electrophysiological responses of the following types of males: (i) pure Hv, (ii) pure Hs, (iii) Hv except for being homozygous for Hs-C27. We recorded independently from B-type and C-type sensilla that are described in Baker et al (50). As expected from Baker et al (50), the neurons in B-type sensilla of pure Hv were activated by low concentrations of Z9-14:Ald but not Z9-16:Ald (Fig.…”

“…Previous single cell recordings from male antennal sensilla have shown differences in response of male Hv and Hs neurons to specific pheromone components (50). We hypothesized that if alleles of the HR genes in Hv and Hs were responsible for the behavioral differences among male genotypes, then we should find distinct electrophysiological responses in moths with Hs versus Hv receptor alleles.…”

Genes encoding candidate pheromone receptors in a moth ( Heliothis virescens )

“…The observation that the novel receptor types HR13-HR16 were expressed in cells that could be confined to long sensilla trichodea supports the view that they are candidate pheromone receptors. The different number of cells expressing the various receptor types may be of particular interest in view of previous electrophysiological findings indicating that a rather high number of sensilla trichoidea type 1, and also of type 2, contain neurons tuned to (Z)-11-hexadecenal, one of the major pheromone components, whereas the secondary pheromone component, (Z)-9-tetradecenal, activates significantly fewer cells (20,21,30). For other minor components of the complex female pheromone blend (31,32), how many cells are activated is unknown.…”

Unusual response characteristics of pheromone-specific olfactory receptor neurons in the Asian corn borer moth,Ostrinia furnacalis

“…The detection of E isomer thus seems to be robust, but is 3% of the sensillum population enough to allow reliable detection of the Z isomer and ratiometric coding? From earlier investigations we know that it is indeed sufficient, with a very low percentage of neurons detecting behaviorally crucial odors (Kalinová et al, 2001;Baker et al, 2004). In the turnip moth, Agrotis segetum, approximately 1-2% of the male olfactory receptor neurons are tuned to an important pheromone component, and in this case no other neurons respond to this specific component (Löfstedt et al, 1982;Hansson et al, 1990).…”