Olfactory receptors on the maxillary palps of small ermine moth larvae: evolutionary history of benzaldehyde sensitivity.
In lepidopterous larvae the maxillary palps contain a large portion of the sensory equipment of the insect. Yet, knowledge about the sensitivity of these cells is limited. In this paper a morphological, behavioral, and electrophysiological investigation of the maxillary palps of Yponomeuta cagnagellus (Lepidoptera: Yponomeutidae) is presented. In addition to thermoreceptors, CO(2) receptors, and gustatory receptors, evidence is reported for the existence of two groups of receptor cells sensitive to plant volatiles. Cells that are mainly sensitive to (E)-2-hexenal and hexanal or to (Z)-3-hexen-1-ol and 1-hexanol were found. Interestingly, a high sensitivity for benzaldehyde was also found. This compound is not known to be present in Euonymus europaeus, the host plant of the monophagous Yponomeuta cagnagellus, but it is a prominent compound in Rosaceae, the presumed hosts of the ancestors of Y. cagnagellus. To elucidate the evolutionary history of this sensitivity, and its possible role in host shifts, feeding responses of three Yponomeuta species to benzaldehyde were investigated. The results confirm the hypothesis that the sensitivity to benzaldehyde evolved during the ancestral shift from Celastraceae to Rosaceae and can be considered an evolutionary relict, retained in the recently backshifted Celastraceae-specialist Y. cagnagellus.
Roessingh
Peter
P
Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Kruislaan 320, 1098 SM, Amsterdam, The Netherlands. Roessingh@uva.nl
Xu
Sen
S
Menken
Steph B J
SB
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D001547:Benzaldehydes / Q000494:pharmacology*; D005075:Biological Evolution; D002245:Carbon Dioxide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology; D007814:Larva / Q000502:physiology*; D009036:Moths / Q000502:physiology*; D018034:Olfactory Receptor Neurons / Q000502:physiology*; D010802:Phylogeny; D010944:Plants; D027824:Rosaceae / Q000502:physiology; D012679:Sense Organs / Q000502:physiology*; D013045:Species Specificity; D013268:Stimulation, Chemical; D013696:Temperature
D001547:Benzaldehydes; D002245:Carbon Dioxide