The peach potato aphid or green peach aphid (M. persicae) is one of the most important pest aphids throughout the world.

Ten years ago the population could be described by a restricted number of genotypes defined by properties such as insecticide resistance, colour and karyotype. It appeared to be almost uniform in terms of protein polymorphism. At this time the Scottish Executive commissioned a core programme to develop molecular markers to distinguish individuals within the M. persicae population.

The outcome was an IGS fingerprinting technique similar to one used on the greenbug in America or the European raspberry aphid. In the following years this revealed that there were many genotypes of M. persicae in the environment. However, in local areas, an IGS pattern was observed over and over again. This suggested that the local populations were dominated by a single clonal type and it was given the name 'braveheart'. It has a number of remarkable properties; sensitivity to insecticides, complete anholocycly (no sexual forms) and a low virus vectoring capability. In 2001, two additional projects have started to build an even more detailed picture of the molecular ecology of this aphid.

The British Council have funded exchange visits with the south of France to allow an analysis of M. persicae from peach orchards using IGS fingerprinting. The Scottish Executive has funded a project to investigate the molecular ecology of M. persicae associated with seed potato crops, and in collaboration with Rothamsted Research, their response to insecticides.