Population Structure and Gene Flow in the White Pine Weevil, <I>Pissodes strobi</I> (Coleoptera: Curculionidae)

Abstract

The white pine weevil, Pissodes strobi (Peck), is a major source of damage to young spruce and pine trees across North America. The species contains a substantial amount of genetic, morphological, and behavioral variation, and identiÞcation of patterns of genetic variation on a broad geographic scale may contribute toward more effective pest management strategies. To estimate maternal gene sow and examine the genetic structure of P. strobi we sequenced an 826-bp fragment of the mitochondrial DNA (mtDNA) COI gene in 130 individuals from 11 locations across Canada. Nested clade analysis of 36 haplotypes yielded three patterns of genetic structuring that are inferred as due primarily to restricted gene sow and contiguous range expansion, with one case of long-distance colonization. Analysis of molecular variance analysis also showed signiÞcant genetic structuring and restricted gene sow among regional populations. Eastern and western populations were divergent, as were the four populations surveyed in British Columbia. Findings were comparable with those of previous studies based on allozyme or randomly ampliÞed polymorphic DNA data, although popu- lation differentiation was greater in mtDNA. Detection of such genetic structure may be important for control programs, because other studies have shown that the conifer hosts of P. strobi provide geographically structured variation in resistance to damage.