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1977, Kline and Mitchell 1979, Wood and McMullen 1983). It was suggested that the same preference holds for interior
spruce as well. Our investigation confirms beyond doubt that it is not the case. Susceptibility of the individual is the
overriding principle that determines whether or not it will be attacked successfully.
In field studies we observed that some seedlings of susceptible families, measuring 50 cm, were attacked by weevil.
In some cases these young seedlings were attacked below the previous year's growth probably due to the inadequate thickness
of the previous year's stem.
To clarify weevil behavior, a number of studies are being initiated to elucidate the biology of white pine weevil in the
interior and its relationship to its host. Verification of resistance in putatively resistant families will also be carried out.
During the spring of 1993 a number of crosses were made using various putatively weevil resistant and susceptible
parents. Judgement as to resistancy or susceptibility was made based on the progenies' weevil resistance performance.
These crosses will form the basis of a number of experiments designed to verify resistancy and susceptibility and to study the
mode and degree of inheritance of these traits.
Future plans include continuation of the inventory of resistant families, provision of material for other agencies, and
incorporation of the accumulated knowledge into the breeding program.
Terpene Studies
Laboratory Studies
Our first intention following the identification of genetically controlled resistance was to try to identify the reason for
resistance. To this aim, we enlisted the help of a team of biochemists lead by Dr. John Manville. They tested eight resistant
and eight susceptible parental clones for terpenes that they judged to be of potential use in differentiating between them. The
tests included both leaf and bark samples.
They were able to classify 15 of the 16 parental clones as to susceptibility or resistance using six bark terpenes with
multivariate technique (Manville et al. 1994). Two of the terpenes are identified (santene and citronellyl acetate) the other
four are not yet identified.
Leaf terpenes also provided similar results. Using six leaf terpenes (terpinolene and five unidentified terpenes), they
were able to classify correctly 15 of 16 samples.
Future plans include validation of the results (i.e., using a random sample of attacked and unattacked trees and
applying the technique to them). They are also working on the identity of the unidentified terpenes.
DNA Marker Studies
We were also interested in investigating the potential differences at the gene level. To study these differences, we
enlisted the help of Dr. John E. Carlson of the University of British Columbia (Carlson et al. 1994).
The team investigated differences between resistant and susceptible interior spruce parents and their open-pollinated
progenies. They constructed genetic linkage maps based on the recently developed Random Amplified Polymorphic DNA
(RAPD) marker system, the first linkage maps available for any spruce species (Hong et al. 1993). Using a "Bulk Parental
Analysis" (BPA) technique developed by the team, they pooled DNA from 12 resistant and 12 susceptible parents. This
technique identified 20 DNA markers putatively associated with weevil resistance.
The followup investigation was carried out on half-sib progenies of the original parents. Needles were collected from
10 half-sib individuals of each parent of the previous study (a total of 240 half-sib progenies).
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