Initial Estimates of the Number of Distinct Populations of Hemlock Woolly Adelgid in the Eastern United States Using Isoenzyme Profiles

Enzyme electrophoretic analysis was used to test the hypothesis that hemlock woolly adelgid in the East are genetically uniform. Adelgids from infested eastern hemlock collected in Virginia, New Jersey, and Connecticut were screened at each of seven putative enzyme loci. The isozyme profiles for four of the enzymes were typical of homozygous and invariant loci for adelgids from the three sites. The remaining isozymes exhibited profiles expected of groups with heterozygous origin but the putative alleles for the adelgids were fixed across all three sites. This initial estimate of large-scale genetic diversity in hemlock woolly adelgid suggests that populations of this insect in the Eastern United States are genetically uniform. If eastern populations of adelgid actually have little or no genetic differentiation between them, the low variability could delay pesticide resistance or favor the breeding of resistant hemlock.