Phylogenetic analysis of the cystine-knot domains in Spätzle from M. sexta and other insect species. The tree was derived from an alignment that can be found in supplementary Figure S2. Numbers at the nodes are bootstrap values as percentage. The nodes signifying Spz2, Spz3, Spz4, Spz5, and Spz6 specific branches are denoted by “•”. The circled bootstrap value indicates that M. sexta Spätzle-1A probably belongs to the Spz1 group. The scale bar indicates the number of substitutions per site. Abbreviations used are: Aa, Aedes aegypti; Ag, Anopheles gambiae; Bm, Bombyx mori; Dm, Drosophila melanogaster; Ms, Manduca sexta; Nv, Nasonia vitripennis; Tc, Tribolium castaneum.