Byers, J.A., Högberg, H.E., Unelius, R., Birgersson, G. &
Löfqvist, J. 1989b. Structure-activity studies on
aggregation pheromone components of Pityogeneschalcographus (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.Chemical Ecology