Gene flow in the exotic colonizing ladybeetle Harmonia axyridis in North America

E. S. Krafsur, T. J. Kring, J. C. Miller, P. Nariboli, J. J. Obrycki, J. R. Ruberson, P. W. Schaefer

Research output: Contribution to journalArticlepeer-review

50 Scopus citations


Gene flow was studied in Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), an exotic, arboreal lady-beetle predator that recently spread rapidly throughout North America. A survey of isozyme polymorphisms showed 30 of 52 resolved putative loci were polymorphic (58%), and the mean heterozygosity was 16.75 ± 2.98% among all loci and 26.31 ± 4.37% at only the polymorphic loci. The mean number of alleles at the 52 loci was 2.01 ± 1.97. Gene frequencies were estimated in populations from Georgia, Virginia, Delaware, Rhode Island, Arkansas, Illinois, Iowa, and Oregon and differed significantly (P < 0.02) at 11 of 16 loci. Three of 16 loci (Fbp, Est-1, Tre) were not in Hardy-Weinberg equilibrium in all populations and are not included in the F statistics. Random mating was indicated within populations (F(IS) = -0.005 ± 0.014) but not among populations (F(ST) = 0.025 ± 0.005). According to Wright's island model, F(ST) estimates the average number of reproducing immigrants to be equivalent to ca. 10 beetles per population per generation. Thus there was a measure of genetic differentiation caused by drift, but this differentiation was small with respect to the large geographical distances among the sampled populations. The genetic data suggest that the founding North American population(s) was substantial.

Original languageEnglish
Pages (from-to)207-214
Number of pages8
JournalBiological Control
Issue number3
StatePublished - Mar 1997

Bibliographical note

Funding Information:
Journal Paper No. J-16398 of the Iowa Agriculture and Home Economics Experiment Station, Ames. Projects 3448 and 3284. Thanks to J. Tropp, USDA-ARS, BIIRL, Newark, Delaware, for providing USDA records of H. axyridis shipments and explaining USDA culture methods. This research was partly supported by USDA-APHIS Grant 12-34-81-0168-GR.


  • Harmonia axyridis
  • breeding structure
  • colonizing species
  • gene flow
  • isozyme variation

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Insect Science


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