Byers, J.A., Högberg, H.E., Unelius, R., Birgersson, G. & Löfqvist, J. 1989b. Structure-activity studies on aggregation pheromone components of Pityogenes chalcographus (Coleoptera: Scolytidae): all stereoisomers of chalcogran and methyl 2,4-decadienoate. Journal of Chemical Ecology 15:685-695.

Abstract-- Syntheses of all four stereoisomers (2S,5S; 2S,5R; 2R,5R; and 2R,5S) of chalcogran, a major component of the aggregation pheromone of Pityogenes chalcographus, and of all four isomers (2Z,4Z; 2Z,4E; 2E,4E; and 2E,4Z) of methyl 2,4-decadienoate (MD), the second major pheromone component, are briefly described. Attraction responses of walking beetles of both sexes were tested to mixtures of the synergistic pheromone components or analogs. These bioassays showed that the E, Z isomer of MD is the most active when tested with chalcogran. When tested with (E, Z)-MD, (2S,5R)-chalcogran was the most active stereoisomer, while 2R,5R and 2R,5S isomers had intermediate activities, and the 2S,5S isomer was inactive. There was no evidence that the relatively less active stereoisomers of chalcogran inhibited or promoted attraction to (2S,5R)-chalcogram with (E, Z)-MD. Male beetles only produce the active E, Z isomer of MD (inactive alone) and their hindguts contain the most active (2S,5R)- and least active (2S,5S)-chalcogran. A mixture of all MD isomers with racemic chalcogran was not significantly different in attractivity compared to (E, Z)-MD with racemic chalcogran, indicating no synergistic or inhibitory effects of the inactive isomers of MD.
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Chemical Ecology