Male-Produced Sex Pheromone of Tibraca limbativentris Revisited: Absolute Configurations of Zingiberenol Stereoisomers and their Influence on Chemotaxis Behavior of Conspecific Females

The rice stalk stink bug, Tibraca limbativentris, is an important rice pest in Brazil with a high invasive potential for Mexico and the USA. The sex pheromone of this species was previously identified as a combination of two stereoisomers of 1,10-bisaboladien-3-ol (zingiberenol), but the absolute configurations of these sesquiterpenes were not determined, neither were their effect(s) on T. limbativentris behavior evaluated. In this study, using two chiral columns, we compared retention times of the two natural 1,10-bisaboladien-3-ol stereoisomers from air-entrainment samples of male T. limbativentris with those of synthetic stereoisomers of 1,10-bisaboladien-3-ol. The results showed that T. limbativentris males produce (3S,6S,7R)-1,10-bisaboladien-3-ol (1) and (3R,6S,7R)-1,10-bisaboladien-3-ol (5) as their sex pheromone. Two new minor, male-specific components were also identified as cis and trans isomers of 2,10-bisaboladien-1-ol (sesquipiperitol). Y-tube olfactometer bioassays showed that the major (3S,6S,7R) isomer 1 was essential for attraction of T. limbativentris females, but the minor (3R,6S,7R) isomer 2 was not, nor did it show synergistic/antagonistic effects when added to the major isomer. The (1S,6S,7R) and (1R,6S,7R) stereoisomers of sesquipepiritol also attracted T. limbativentris females.