Altered olfactory receptor neuron responsiveness in rare Ostrinia nubilalis males attracted to the O. furnacalis pheromone blend.

ABSTRACT

Three percent of E-strain Ostrinia nubilalis males fly upwind in response to the Ostrinia furnacalis pheromone blend [a 4060 ratio of (E)-12-tetradecenyl acetate to (Z)-12-tetradecenyl acetate (E12-14OAc to Z12-14OAc)], in addition to their own pheromone blend [a 991 ratio of (E)-11-tetradecenyl acetate to (Z)-11-tetradecenyl acetate) (E11-14OAc to Z11-14OAc)]. We assessed the olfactory receptor neuron (ORN) responses of these behaviorally "rare" males versus those of normal males. For the three ORNs housed within each sensillum, we tested responsiveness to Z12-14OAc, E12-14OAc, Z11-14OAc, E11-14OAc, and the behavioral antagonist (Z)-9-tetradecenyl acetate (Z9-14OAc). Z11-14OAc, E11-14OAc, and Z9-14OAc stimulated ORNs exhibiting distinct small, large, and medium spike sizes, respectively. For rare and normal males, both Z12-14OAc and E12-14OAc usually elicited responses from the largest-spiking ORN. In many ORNs of normal males, Z12-14OAc or E12-14OAc stimulated the smaller-spiking ORN that is responsive to Z11-14OAc. In rare males, detectable ORN responses from the smaller-spiking ORN in response to Z12- and E12-14OAc were virtually non-existent. These differences in ORN tuning in rare males will tend to create an ORN firing ratio between the large- and small-spiking ORNs in response to the O. furnacalis blend that is similar to that elicited by the O. nubilalis blend.