title: Sex pheromone receptor specificity in the European corn borer moth, Ostrinia nubilalis.
abstract: BACKGROUND
  The European corn borer (ECB), Ostrinia nubilalis (Hubner), exists as two separate sex pheromone races. ECB(Z) females produce a 97ratio3 blend of Z11- and E11-tetradecenyl acetate whereas ECB(E) females produce an opposite 1ratio99 ratio of the Z and E isomers. Males of each race respond specifically to their conspecific female's blend. A closely related species, the Asian corn borer (ACB), O. furnacalis, uses a 3ratio2 blend of Z12- and E12-tetradecenyl acetate, and is believed to have evolved from an ECB-like ancestor. To further knowledge of the molecular mechanisms of pheromone detection and its evolution among closely related species we identified and characterized sex pheromone receptors from ECB(Z).
  
  
  METHODS
  Homology-dependent (degenerate PCR primers designed to conserved amino acid motifs) and homology-independent (pyrophosphate sequencing of antennal cDNA) approaches were used to identify candidate sex pheromone transcripts. Expression in male and female antennae was assayed by quantitative real-time PCR. Two-electrode voltage clamp electrophysiology was used to functionally characterize candidate receptors expressed in Xenopus oocytes.
  
  
  CONCLUSIONS
  We characterized five sex pheromone receptors, OnOrs1 and 3-6. Their transcripts were 14-100 times more abundant in male compared to female antennae. OnOr6 was highly selective for Z11-tetradecenyl acetate (EC(50) = 0.86+/-0.27 microM) and was at least three orders of magnitude less responsive to E11-tetradecenyl acetate. Surprisingly, OnOr1, 3 and 5 responded to all four pheromones tested (Z11- and E11-tetradecenyl acetate, and Z12- and E12-tetradecenyl acetate) and to Z9-tetradecenyl acetate, a behavioral antagonist. OnOr1 was selective for E12-tetradecenyl acetate based on an efficacy that was at least 5-fold greater compared to the other four components. This combination of specifically- and broadly-responsive pheromone receptors corresponds to published results of sensory neuron activity in vivo. Receptors broadly-responsive to a class of pheromone components may provide a mechanism for variation in the male moth response that enables population level shifts in pheromone blend use.
authors.affiliation: Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman, Montana, USA. kwanner@montana.edu
authors.forename: Kevin W
authors.initials: KW
authors.lastname: Wanner
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Nichols
authors.forename: Jean E
authors.initials: JE
authors.lastname: Allen
authors.forename: Peggy L
authors.initials: PL
authors.lastname: Bunger
authors.forename: Stephen F
authors.initials: SF
authors.lastname: Garczynski
authors.forename: Charles E
authors.initials: CE
authors.lastname: Linn
authors.forename: Hugh M
authors.initials: HM
authors.lastname: Robertson
authors.forename: Charles W
authors.initials: CW
authors.lastname: Luetje
mesh_terms: D000818:Animals; D005260:Female; D008297:Male; D009036:Moths / Q000502:physiology; D016133:Polymerase Chain Reaction; D018035:Receptors, Odorant / Q000378:metabolism*; D012724:Sex Attractants / Q000378:metabolism*; D012726:Sexual Behavior, Animal
chemical_list: D018035:Receptors, Odorant; D012724:Sex Attractants