Birgersson, G., Byers, J.A., Bergström, G., & Löfqvist,
J. 1990. Production of pheromone components, chalcogran
and methyl (E,Z)-2,4-decadienoate, in the spruce
engraver Pityogenes chalcographus. Journal of Insect
Physiology 36:391-395. pdf
Male Pityogenes chalcographus looking for a place to bore into bark of Norway spruce
Abstract--
Capillary gas chromatography and mass spectrometry were used to
quantify the amounts of E- and Z- chalcogran amd methyl
(E, Z)-2,4-decadienoate (E, Z-MD), pheromone synergists of the bark beetle
Pitygenes chalcographus (Coleoptera: Scolytidae). Males were exposed
or not to vapours of host (Norway spruce, Picea abies) oleoresin or
allowed to feed in host logs prior to extraction of body parts and
hindguts for pheromone synergists. E, Z-MD and chalcogran were
produced sex-specifically in males, and only after feeding on
host-plant tissue. The pheromone synergists were not produced during
exposure to oleoresin vapours. Several oxygenated monoterpenes
(including trans-verbenol, myrtenol, and trans-myrtanol) were found
in feeding males. The amounts of the pheromone synergists in unmated
feeding males remained relatively constant over a 3.5 day period. In
contrast to many other pheromone components of bark beetles,
including chalcogran, E, Z-MD was found primarily in the male's body
(head and thorax) with less in the hindgut (abdomen). The probable
acetogenic origins of both pheromone components indicate that the
species has evolved control over production and is thus not dependent
on host precursors as expected in many other bark beetles.
Chemical Ecology