Male-produced sex pheromone of Tibraca limbativentris revisited: absolute configurations of zingiberenol stereoisomers and their influence on chemotaxis behaviour of conspecific females

Authors: BLASSIOLLI-MORAES, MARIA CAROLINA - Embrapa; Khrimian, Ashot; MICHEREFF, M.F.F. - Embrapa; MAGALHAES, D.M. - Embrapa; HICKEL, E. - Epagri; FREITAS, T.F.S DE - University Of Rio Grande Do Sul; BARRIGOSSI, A. - Embrapa; LAUMANN, R.A. - Embrapa; TELLES, A. - University Of Brasilia; GUGGILAPU, SRAVANTHI - University Of Maryland; SILVA, C.C - Embrapa; SANT'ANA, J. - University Of Rio Grande Do Sul; BORGES, MIGUEL - Embrapa

Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/11/2019
Publication Date: 12/16/2019
Citation: Blassiolli-Moraes, M., Khrimian, A., Michereff, M., Magalhaes, D., Hickel, E., Freitas, T., Barrigossi, A., Laumann, R., Telles, A., Guggilapu, S.D., Silva, C., Sant'Ana, J., Borges, M. 2019. Male-produced sex pheromone of Tibraca limbativentris revisited: absolute configurations of zingiberenol stereoisomers and their influence on chemotaxis behaviour of conspecific females. Journal of Chemical Ecology. 46:1-9.

Interpretive Summary: The the rice stalk stink bug an important rice pest in Brazil with a high invasive potential in Mexico and USA. Its control in Brazil is based heavily on insecticide applications, and there is no efficient monitoring method for this pest. The sex pheromones (or chemicals released by insects to trigger a response of the same species) have been successfully used in monitoring of different type of insect. The rice stalk stink bug pheromone was previously identified as a combination of two chemicals of the same molecular formula but their structures had not been fine-tuned. The current manuscript describes further identification of their stereo structures and the assignment of the absolute configurations (spacial arrangements of certain groups). Laboratory bioassay confirmed the identification. This finding will allow chemists to direct their pheromone preparation procedures to target specifically the two compounds that we identified. The work is of interest to entomologists, organic chemists, and pest management dealing with invasive species.

Technical Abstract: The rice stalk stink bug, Tibraca limbativentris, is an important rice pest in Brazil with a high invasive potential in Mexico and USA. Its control in Brazil is based heavily on insecticide applications, and there is no efficient monitoring method. The sex pheromone of this species was previously identified as a combination of two stereoisomers of 1,10-bisaboladien-3-ol (a.k.a zingiberenol), but the absolute configuration of this sesquiterpene was not determined, neither its effect on T. limbativentris behaviour was evaluated. Therefore, the aim of this study was to identify the absolute configurations of the two isomers of 1,10-bisaboladien-3-ol produced by T. limbativentris males, and to evaluate the influence of these isomers on conspecific females' behaviour in Y-tube olfactometer. The GC analyses of air-entrainment samples from male T. limbativentris against all possible stereoisomers of 1,10-bisaboladien-3-ol, on two different chiral columns, showed that males produce (3S,6S,7R)-1,10-bisaboladien-3-ol (1) and (3R,6S,7R)-1,10-bisaboladien-3-ol (5). During these analysis two new minor male specific components were identified as cis and trans isomers of 2,10-bisaboladien-1-ol (sesquipiperitol). The Y-tube olfactometer bioassays showed that the major (3S,6S,7R)-isomer 1was essential in the attraction of T. limbativentris females, but the minor (3R,6S,7R) isomer 2 was not, nor did it show synergistic/antagonistic effects in females' attraction.. The (1S,6S,7R) and (1R,6S,7R) stereoisomers of sesquipepiritolalso attracted T. limbativentris females, suggesting thier importance for thechemotaxis response.