Maternal factors of female wasps that are injected into hosts with their eggs at oviposition play a major role in strategies used by insect parasitoids to overcome host immunity, and to regulate host physiology during early stages of parasitism. Here, we attempted to precisely determine and compare the protein patterns injected by the endoparasitoid Aphidius ervi into two different host systems. Chitosan beads of aphid size designed as artificial and physiologically inert hosts were used as oviposition medium, to be compared with the natural aphid host as young nymphs of Macrosiphum euphorbiae. Proteins that the A. ervi wasp injects into hosts at oviposition were separated by SDS–PAGE, complemented with pro- teomic techniques. Analyses conf...