Cytogenetic analysis on the gall generation of two aphid species: Tetraneura nigriabdominalis and T-ulmi

We carried out a comparative cytogenetic study on gall-forming generations of Tetraneura nigriabdominalis and Tetraneura ulmi using NOR and C-banding followed by Giemsa, Chromomycin A(3) (CMA(3)) and DAPI staining reactions in order to improve our knowledge of these species and better define their identification. In both species, C-banding revealed that heterochromatin was not equilocated on each chromosome. Moreover, in T. nigriabdominalis the C-banding technique identified B chromosomes. The different response to the CMA(3) and DAPI staining reactions after C-banding points out heterogeneity of the heterochromatic DNA composition in both species. Moreover, both CMA(3) and silver staining revealed heteromorphism of NORs.