Manipulations of egg-gallery length to vary brood density in spruce beetle, Dendroctonus rufipennis (Coleoptera: Scolytidae): Effects on brood survival and quality

Different brood densities were produced under a constant bark surface area of the spruce host, by excising egg-producing female <i>Dendroctonus rufipennis</i> from the host material after they had excavated galleries of specified lengths. This procedure allowed a constant attack density. The numbers of adult progeny produced/cm of egg-gallery were significantly greater from bark slabs with short galleries and low densities: the sizes (pronotal widths) of adult progeny of both sexes were also significantly greater from low than from high densities; and the distribution patterns of chromatin differed significantly among high, medium and low densities