Population genetics of Tuberolachnus salignus,an obligate parthenogenetic aphid

This study reports the results obtained in an investigation of the putatively parthenogenetic aphid species Tuberolachnus salignus Gmelin. Tuberolachnus salignus is one of the largest aphid species in the world but where and how it overwinters is not known. It has recently become noteworthy because it is increasingly found on commercially grown willows used in bioenergy production. Seven newly-developed polymorphic microsatellite markers were used to investigate the genetic diversity of the species, and also to confirm its reproduction strategy. Tuberolachnus salignus shows very low clonal diversity; only 16 genotypes were found in 660 specimens from 27 populations in five countries. There was limited geographical structuring in the samples, although the two most common genotypes, which comprised more than half of the specimens collected, had a very wide distribution. Furthermore, we determined that these aphids, which live in very dense colonies, can consist of more than one genotype, suggesting aggregation of colonizing T. salignus. These results confirm the parthenogenetic nature of T. salignus and demonstrate the presence of common genotypes that are widespread in time and space