Identification of aphids of Aphis frangulae-group living on Lamiaceae species through DNA barcode

The genus Aphis frangulae-group living on Lamiaceae includes several postulate species, which are morphologically indistinguishable. As a consequence, identification is possible only on the basis of the host plant or life cycle. This study tested the utility of a fragment (614 bp) of mitochondrial cytochrome oxidase 1 (COI) with the aim of identifying the species and/or to confirm the previous classification based on host plant and data reported in the literature. Although the general nucleotide variability found was rather low, the analysis enabled the separation and identification of all the specimens collected. In some cases, the lack of nucleotide variability among postulated taxa indicates the limits of identification based on biological traits. Consequently, based on the molecular analysis, the postulate species A. symphyti, A. stachydis and A. lamiorum should be regarded as synonymous of A. frangulae.