Shared Pheromone Compounds in Neotropical Rice Stink Bugs: The Role of Zingiberenol and Sesquipiperitol

The small black stem bug, Paratibraca (= Glyphepomis) spinosa (Campos and Grazia 1998), is a rice pest in Brazil and is part of a complex of stink bugs that includes Oebalus poecilus (Dallas) and Tibraca limbativentris Stål. Together, these pentatomid species pose a serious threat to rice crops throughout South America. In this study, we identified the sex pheromone of P. spinosa. Our findings revealed that male P. spinosa produces four male-specific compounds identical to those produced by T. limbativentris males. These include (3S,6S,7R)-1,10-bisaboladien-3-ol and (3R,6S,7R)-1,10-bisaboladien-3-ol (zingiberenols), both sharing the same absolute configuration as the 1,10-bisaboladien-3-ol from T. limbativentris; along with two minor male-specific components: the cis and trans isomers of 2,10-bisaboladien-1-ol (sesquipiperitol). Y-tube olfactometer bioassays demonstrated that P. spinosa females were attracted to the odours of live males, whereas males showed no attraction to either sex. Females were particularly drawn to male volatiles, especially the fraction containing the compounds 1,10-bisaboladien-3-ol and 2,10-bisaboladien-1-ol. When tested with synthetic compounds, females were attracted to a blend of the two isomers, (3S,6S,7R)-1,10-bisaboladien-3-ol and (3R,6S,7R)-1,10-bisaboladien-3-ol, in the same ratio as naturally produced by males. Given that the sex pheromone compounds identified in P. spinosa are identical to those of T. limbativentris, we conducted bioassays with live heterospecific insects. In olfactometer bioassays, the females of both species were attracted by the odours of heteroespecific males.