Differentiation between Aphis pomi and Aphis spiraecola using multiplex realâ•’time PCR based on DNA barcode sequences

The green apple aphid (Aphis pomi De Geer 1783) and the spirea aphid (Aphis spiraecola Patch 1914) are pests of apples in North America (Foottit et al. 2006). They play a role in disease transmission (Blackman and Eastop 2000) and affect healthy growth of their hosts (Kaakeh et al. 1993). Although management regimes exist to effectively control these pests, they differ significantly because of varying susceptibility of each species to common pesticides (Lowery et al. 2005, 2006) and differences in their life cycles (Foottit et al. 2009). Therefore, accurate identification of the species present is essential for pest control. However, the identification process is complicated because of the morphological similarity between these two species. As a result, confusion between A. pomi and A. spiraecola often occurs (Blackman and Eastop 2000; Foottit et al. 2009). DNA barcoding using the 5¢ end of the mitochondrial cytochrome C oxidase I (COI) gene (Hebert et al. 2003) has been proven to accurately identify most species of Aphididae (Foottit et al. 2008; Lee et al. 2011). A further study demonstrated that DNA