Canadian Forest Service Publications
White pine weevil attack on white spruce: A survival time analysis. 2000. He, F.; Alfaro, R.I. Ecological Applications 10(1): 225-232.
Available from: Pacific Forestry Centre
Catalog ID: 5391
CFS Availability: Order paper copy (free)
The survival time of a white spruce tree (Picea glauca (Moench) Voss) with respect to the attack by the white pine weevil (Pissodes strobi (Peck)) was defined as the number of years until an attack occurred. In this context, resistant trees are those capable of delaying attacks rather than preventing attacks. This study investigated the patterns of survival times of resistant and susceptible trees in a progeny trial of white spruce in the interior of British Columbia, Canada. By doing so, we demonstrated that survival time analysis, a technique specifically developed for dealing with clinical medicine and industrial reliability tests, was a very useful approach in analyzing resistance of hosts to herbivore attack. The results suggested that survivorship of resistant trees was significantly different from the susceptible trees, as expected. The median survival time of susceptible trees was around 12 years after seeding, while it was 21 years for resistant trees. The survival times of white spruce trees were identified adequately following a lognormal distribution. Based on the estimated hazard functions of the lognormal distribution, the most severe weevil infestation was predicted to occur at the age of 19 years for susceptible trees, and at 26 years for resistant trees. Infestation level was affected by several factors, such as tree height, seasonal temperature and precipitation. An accelerated failure-time model was used to evaluate the effect of these factors on survivorship. The identification of resistant or susceptible trees by survival times is to be incorporated into an integrated pest management program for the white pine weevil in British Columbia.
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