Meeting Abstract
24.2 Jan. 5 Importance of odorant chirality in an insect-plant interaction REISENMAN, CE*; RIFFELL, JA; HILDEBRAND, JG; University of Arizona; University of Arizona; University of Arizona carolina@neurobio.arizona.edu
Olfaction plays decisive roles in moths for finding mates, food, and oviposition sites. Odor compounds differ in structural features, and the importance of enantiomers (mirror-image forms of a single chemical compound) is well established in olfaction. Depending on the receiver, some enantiomers might be discriminated while others might have similar representations. We investigated this issue from the perspectives of neurobiology, chemical ecology, and behavior in the sphinx moth Manduca sexta. By means of intracellular recording and staining, we found that certain female-specific neurons in the primary olfactory centers respond preferentially to the (+) enantiomer of linalool, a volatile compound commonly emitted by plants. We investigated the enantiomeric composition of linalool emitted by Datura wrightii, a preferred hostplant of M. sexta. The flowers of this plant, which are almost exclusively pollinated by adult M. sexta, emit scent comprising several odorants including linalool, which we found to be >99% (+) enantiomer. Vegetative plant structures emit only trace amounts of linalool. In preliminary behavioral experiments individual female moths were confined overnight in a flight cage containing two D. wrightii plants � one bearing an odorless paper �flower� (control) and the other, a paper flower impregnated with a synthetic mixture of D. wrightii floral odorants. We counted the eggs on each plant the following morning. In one series of experiments the floral blend contained (+)linalool, while in the other series, we used (-) linalool. Plants with the floral blend containing (+) linalool were preferred over control plants, while plants with the (-) linalool blend were avoided. These results show that enantiomers are discriminated by the moth�s olfactory system and may be important for sensory control of natural behavior.
