Spruce shoot weevil trial in the interior of British Columbia, Canada.

A) Photo to the left: emerging Pissodes strobi individual during the weevil rearing experiment (photo credit: Ward Strong); photo to the right: Kalamalka Research Station based Interior spruce weevil trial after thinning (photo credit: Val Ashley). B) Spatial distribution for classes of attack severity (upper left plot, A00), egg punctures occurrence (upper right plot, E00) in the year 2000, as well as for heights measured in cm at four years (bottom left plot, HT4 in the year 1998) and five years of age (bottom right plot, HT5 in the year 1999), respectively, on an individual tree basis within the experimental plot. Family plots are distinguished in the grid, where individual trees are indexed by row and column numbers. The plot outline of the entire trial on a family basis is provided in [33]. Forty-two controlled crosses were generated by mating resistant with resistant, resistant with susceptible, and susceptible with susceptible parents. The ranking in terms of weevil resistance of the individual Interior spruce parents is known and was done previously [13]. The evaluation of attacks was done following artificial weevil infestation of the spruce resistance trial. Height data from pre-attack years are shown. The colour code for ascending phenotypic values (that is for classes of attack severity, egg punctures occurrence, heights) is provided to the right of each plot outline. No formal statistical analysis on the spatial distribution of the weevil attack severity was attempted for this experiment designed as family-based plots where each plot contained 25 individuals of the same family.