HOST EFFECTS ON ALLOZYME AND MORPHOLOGICAL VARIATION OF THE MOUNTAIN PINE BEETLE,DENDROCTONUS PONDEROSAEHOPKINS (COLEOPTERA: SCOLYTIDAE)

Abstract

AbstractAllozyme and morphological variation were investigated for mountain pine beetle populations in limber pine and lodgepole pine in Alberta and British Columbia. Fourteen gene loci, five of which were polymorphic, were studied. Heterozygote deficiencies were detected at the ME locus for 13 of the 16 groups of beetles sampled. Selection against heterozygotes appears to be the most plausible explanation. There was no significant difference in heterozygosity between beetles from lodgepole pine and those from limber pine. Relatively high levels of genetic differentiation, in terms of allele frequency, were observed among beetles from different sites, host species, seasons, and individual conspecific trees within a site. Low levels of differentiation were observed between beetle generations at a site and between sexes. We attribute significant host-associated genetic differentiation to differential survival in hosts rather than to differential host preference of beetle genotypes. Standardized discriminant function analysis of 12 morphological characters indicated significant differences in beetle shape between sexes, host species, and among sites. Overall, there was little evidence of preferential host selection by beetles which would imply substructuring ofDendroctonus ponderosaeHopkins populations along host lines.