Fig. 1E and F show that IMD mutant larvae were not sensitive to infection with Ecc15, although the induction of the antibacterial peptide gene Dpt was almost abrogated in the mutant. From these results, we conclude that survival, AMP expression and bacterial number upon bacterial infection by septic injury with a tungsten needle could be consistently measured in Drosophila larvae, and that the role of the Toll pathway was somewhat different during this process compared with the adult infection model. This evidence concerns the gene TLR4 and bacterial infectious disease.