|Abstract or Summary
- Populations of Dendroctonus ponderosae Hopkins from three pine
hosts, Pinus ponderosa Laws., P. contorta Dougl. and P. monticola
Dougl., were sampled with regard to their acoustic signals, the
morphology of their stridulatory apparatus and some aspects of their
emergence behavior. Comparisons of these characteristics were made
between samples from different hosts and/or years.
Statistical comparisons were made of acoustic signals in four
behavioral contexts: male attractant stridulation, male rivalry
stridulation, male stress stridulation and female acoustic response to
an intruder. Four parameters were considered: the number of spikes
per chirp, the spike rate, the duration of the chirp and the number of
subchirps per chirp. Differences, in both multivariate comparisons of
all stridulation parameters simultaneously and in comparisons of
individual parameters, existed between samples in all behavioral
contexts except male attractant stridulation. On this basis, male
attractant stridulation is ruled out as .? possible interpopulation
Seven different morphological characters were measured: the
length of the left elytron, the length of the elytral pars stridens,
the number of ridges in the elytral pars stridens, the percentage of
ridges in the posterior half of the elytral pars stridens, the
distance between the spines of the male plectral processes, and the
length and number of ridges of the female sternal pars stridens.
Statistical comparisons of individual characters were made between
samples and between males and females of the same sample. Where
differences were significant, D. ponderosae from ponderosa pine were
always larger than D. ponderosae from western white pine which were in
turn always larger than D. ponderosae from lodgepole pine. In samples
from all three hosts females were larger than males in the length of
the left elytron and in the percentage of ridges in the posterior half
of the elytral pars stridens but generally similar in the length and
number of ridges in the elytral pars stridens.
Several differences in emergence behavior existed between
populations from white pine and populations from either ponderosa or
lodgepole pine. White pine samples had a greater proportion of males
emerging than ponderosa and lodgepole samples and the proportion of
males emerging did not increase over the emergence period in white
pine samples as it did in both ponderosa and lodgepole samples.
Emergence of beetles from white pine was rhythmic and closely
synchronous with temperature whereas emergence from ponderosa and
lodgepole tended to be rhythmic but asynchronous with temperature.