Rhopalosiphum aphids in New Zealand. II. DNA sequences reveal two incompletely described species

We applied DNA sequence analysis to Rhopalosiphum aphids, which we had previously characterised by random amplified polymorphic DNA (RAPD) PCR. By comparing two gene sequences, we confirmed that Rhopalosiphum sp. T was a species previously undescribed from New Zealand. Significant differences were also observed between a DNA sequence from New Zealand R. near insertum and a European R. insertum sequence deposited in GenBank. The ribosomal ITS proved to be a more robust marker for aphid identification than suggested by previous studies, and intraspecies variation within the ribosomal ITS sequences appeared to be extremely low. Specific PCR primers based upon differences in the ITS sequence were used to rapidly distinguish R. padi from other Rhopalosiphum species found on New Zealand grain crops.