title: Olfactory discrimination among sex pheromone stereoisomers: chirality recognition by pink hibiscus mealybug males.
abstract: Our previous field studies suggested that the two chiral centers in the sex pheromone of pink hibiscus mealybug, Maconellicoccus hirsutus, could elicit different male responses. The chiral center in the acid moiety of the pheromone seemed to be more critical than the alcohol portion of the pheromone molecule for attractiveness. The objective of the current study was to test this hypothesis by deploying stereoisomeric blends in pheromone traps. Captures of male M. hirsutus showed that pheromone with the naturally occurring (R)-maconelliyl (S)-2-methylbutanoate and (R)-lavandulyl (S)-2-methylbutanoate [R-S configuration] was most attractive and that pheromone with the unnatural S-S configuration was less attractive. In addition, the RS-R blend (containing R-R and S-R stereoisomers) yielded captures of male M. hirsutus that were comparable to blank controls, and an inhibitory effect was observed when R-R and S-R were combined with naturally occurring R-S blend. These results suggest a unique chirality recognition mechanism; olfactory discrimination among different pheromone stereoisomers depends upon both asymmetric centers. The S configuration on the acid moiety elicits attraction, whereas the R configuration induces inhibition. However, the attractive activity shows some degree of tolerance toward chirality change in the alcohol portion of the pheromone molecules.
authors.affiliation: Chemicals Affecting Insect Behavior Laboratory, Beltsville Agriculture Research Center-West, USDA, Agriculture Research Service, MD 20705, USA. zhanga@ba.ars.usda.gov
authors.forename: Aijun
authors.initials: A
authors.lastname: Zhang
authors.forename: Shifa
authors.initials: S
authors.lastname: Wang
authors.forename: Justin
authors.initials: J
authors.lastname: Vitullo
authors.forename: Amy
authors.initials: A
authors.lastname: Roda
authors.forename: Catharine
authors.initials: C
authors.lastname: Mannion
authors.forename: J Christopher
authors.initials: JC
authors.lastname: Bergh
mesh_terms: D000818:Animals; D002087:Butyrates / Q000737:chemistry*; D003503:Cyclobutanes; D004192:Discrimination, Psychological / Q000502:physiology*; D006430:Hemiptera / Q000502:physiology*; D008297:Male; D008968:Molecular Conformation; D012724:Sex Attractants / Q000737:chemistry* / Q000502:physiology; D012903:Smell / Q000502:physiology*; D013237:Stereoisomerism; D013729:Terpenes
chemical_list: C488425:(2,2-dimethyl-3-(1-methylethylidene)cyclobutyl)methyl 2-methylbutanoate; C488424:2-isopropenyl-5-methyl-4-hexenyl 2-methylbutanoate; D002087:Butyrates; D003503:Cyclobutanes; D012724:Sex Attractants; D013729:Terpenes