ABSTRACT: The aphids Myzus persicae and Macrosiphum euphorbiae are major pests that are found simultaneously on the same potato (S. tuberosum) plants in open fields. In that context, the Electrical Penetration Graph technique (DC-EPG) was used to determine the effects of either M. persicae or M. euphorbiae first and localised infestation of S. tuberosum (cv Désirée) on subsequent feeding behavior of these two species. Although the presence of M. persicae does not modify M. euphorbiae feeding behaviour, it triggers 50 % reduction of phloem sap ingestion for conspecific aphids. An infestation of M. euphorbiae leads to a 60 % reduction of the phloem sap ingestion for both aphid species. Such a reduction of phloem ingestion suggests that an aphid infestation induces a systemic response which leads to a reduction of the phloem sap appetency. Our laboratory results suggest that a first infestation may influence further aphid colonisation.