Genetic relatedness of North American populations of Tomicus piniperda (Coleoptera:Scolytidae).

We used DNA fingerprinting by random amplified polymorphic (RAPD) DNA and electrophoretic characterization of esterase isozymes to investigate the genetic relatedness of North American populations of the exotic bark beetle Tomicus piniperda (L.). Cluster analyses of genetic distances among populations identified the Illinois population as an outlier population with mean genetic distances to other populations averaging 0.895 (where complete dissimilarity = 2), compared with genetic distance averages of 0.595 among populations excluding Illinois. When genetic distance means and geographical distance between populations were compared, the results suggested that T. piniperda populations in the United States were established separately in Illinois near Lake Michigan and in Ohio along Lake Erie. Molecular markers indicated that insects derived from the 2 founder groups were interbreeding in contiguous regions in western Indiana.