On the Genetic Structure of Harmonia axyridis (Coleoptera, Coccinellidae) Populations in Native and Invasive Ranges, View from a Position of Molecular Genetics

Harmonia axyridis Pallas (1773) (Coleoptera: Coccinellidae) is one of the most studied invasive species of insects. H. axyridis appeared in Europe in 2000, and from that moment, the expansion of the species to the east has continued in the direction of the native range. To determine the populations that are sources for the formation of the eastern front of invasion, we studied the variability and genetic structure of invasive and native populations of the species using 12 microsatellite markers. We found that there was no decrease in the average expected heterozygosity in invasive populations as compared with native populations; however, a significant decrease in the allelic diversity was observed. It was demonstrated that the allelic diversity in invasive populations depends on their “age.” We found that the level of differentiation of invasive populations is significantly higher than in the group of native populations. Cluster analysis demonstrated that European invasive H. axyridis populations are divided into two groups, indicating their origin as a result of several waves of migration. Our analysis demonstrated no significant differences between the groups of native populations, which is most likely a consequence of homoplasy of microsatellite markers that arose in the course of the evolution of the species. Our results suggest that the eastern front of invasion is formed by descendants of northern Italian WNA propagule.