Byers, J.A., Birgersson, G., Löfqvist, J., Appelgren, M.,
& Bergström, G. 1990a. Isolation of pheromone
synergists of bark beetle, Pityogenes chalcographus,
from complex insect-plant odors by fractionation and
subtractive-combination bioassay. Journal of Chemical
Ecology 16:861-876.
Male Pityogenes chalcographus looking for a place to bore into bark of Norway spruce
Abstract--
Capillary gas chromatography with columns of different polarity and
two-dimensional fractionation of effluents were used with novel
subtractive-combination bioassays to rigorously isolate host- and
insect-produced pheromone synergists of the bark beetle Pityogeneschalcographus (Coleoptera: Scolytidae). Methyl (E, Z)-2,4-decadienoate
(E, Z-MD) and the previously identified chalcogran were
found to be synergistically attractive to both sexes. E, Z-MD was
produced sex-specifically in males, and only when they had fed on
host-plant tissue. A Norway spruce monoterpene fraction (including
alpha-pinene, beta-pinene, and camphene) increased the attractive
response to the pheromone components. Dose-response curves for E, Z-MD
and chalcogran in the laboratory bioassay indicated the two
components are highly synergistic. The isolation methods are
important for further progress in identifying certain semiochemical
synergists found in trace amounts in complex chemical mixtures, such
as when insects must feed in host plants in order to produce
pheromone.
Chemical Ecology
Male Pityogenes chalcographus looking for a place to bore into bark of Norway spruce
