title: Interference of plant volatiles on pheromone receptor neurons of male Grapholita molesta (Lepidoptera: Tortricidae).
abstract: In moths, sex pheromone components are detected by pheromone-specific olfactory receptor neurons (ph-ORNs) housed in sensilla trichodea in the male antennae. In Grapholita molesta, ph-ORNs are highly sensitive and specific to the individual sex pheromone components, and thus help in the detection and discrimination of the unique conspecific pheromone blend. Plant odors interspersed with a sub-optimal pheromone dose are reported to increase male moth attraction. To determine if the behavioral synergism of pheromone and plant odors starts at the ph-ORN level, single sensillum recordings were performed on Z8-12:Ac and E8-12:Ac ph-ORNs (Z-ORNs and E-ORNs, respectively) stimulated with pheromone-plant volatile mixtures. First, biologically meaningful plant-volatile doses were determined by recording the response of plant-specific ORNs housed in sensilla auricillica and trichodea to several plant odorants. This exploration provided a first glance at plant ORNs in this species. Then, using these plant volatile doses, we found that the spontaneous activity of ph-ORNs was not affected by the stimulation with plant volatiles, but that a binary mixture of sex pheromone and plant odorants resulted in a small (about 15%), dose-independent, but statistically significant, reduction in the spike frequency of Z-ORNs with respect to stimulation with Z8-12:Ac alone. The response of E-ORNs to a combination of E8-12:Ac and plant volatiles was not different from E8-12:Ac alone. We argue that the small inhibition of Z-ORNs caused by physiologically realistic plant volatile doses is probably not fully responsible for the observed behavioral synergism of pheromone and plant odors.
authors.affiliation: University of Lleida, Department of Crop and Forest Sciences, Av. Alcalde Rovira Roure 191, 25198 Lleida, Spain. Electronic address: nnnbyrareddy20@gmail.com.
authors.forename: Byrappa
authors.initials: B
authors.lastname: Ammagarahalli
authors.affiliation: University of Lleida, Department of Crop and Forest Sciences, Av. Alcalde Rovira Roure 191, 25198 Lleida, Spain. Electronic address: cesar.gemeno@pvcf.udl.cat.
authors.forename: César
authors.initials: C
authors.lastname: Gemeno
mesh_terms: D000818:Animals; D057506:Arthropod Antennae / Q000378:metabolism*; D008297:Male; D027845:Malus / Q000737:chemistry; D009036:Moths / Q000502:physiology*; D009812:Odorants; D018034:Olfactory Receptor Neurons / Q000502:physiology*; D010675:Pheromones / Q000378:metabolism*; D000068239:Prunus persica / Q000737:chemistry; D043563:Receptors, Pheromone / Q000502:physiology*; D058618:Sensilla / Q000378:metabolism; D055549:Volatile Organic Compounds / Q000494:pharmacology*
chemical_list: D010675:Pheromones; D043563:Receptors, Pheromone; D055549:Volatile Organic Compounds
keywords: Olfactory receptor neuron; Plant volatiles; Sex pheromone; Single sensillum recording