Different signalling pathways are activated following immune challenges in Drosophila: The Toll and Imd pathways are induced following infection by gram-positive and gram-negative bacteria, respectively (De Gregorio et al., 2002; Ferrandon et al., 2007), and the EGFR pathway is induced following wasp infestation (Sinenko et al., 2011). This evidence concerns the gene TLR4 and infection.