With the exception of defensin-2 (identified from genomic sequences generated during this project; Klaudiny et al., 2005) all of the honey bee antimicrobial peptides were first characterized by protein sequencing (Casteels-Josson et al., 1994) , a fact that belies the difficulty in discovering such genes by sequence similarity across the millions of years separating insect species. Still, there is no evidence for close paralogues for any of the honey bee antimicrobial peptides, in contrast to such patterns in other insects (e.g. the gene-rich cecropin family). Five of the six bee antimicrobial peptides are up-regulated across diverse immune challenges ( Fig. 3; Evans, 2004) . Honey bees possess only one prophenoloxidase (proPO) gene, versus three and nine in Drosophila and Anopheles, respectively. Like most proPO, the honey bee proPO lacks a signal peptide and has the consensus sequence of NRFG around the activation site. The gene encoding proPO is expressed more strongly in older honey bee larvae and pupae (Lourenço et al., 2005) . This gene was not up-regulated in our challenge experiments, but a gene identified as a proPO activator was up-regulated during natural infection (Fig. 3) . There are only three lysozymes in the honey bee genome, two c-(chicken) type and one i-(invertebrate) type. One of the c-class lysozymes is up-regulated by challenged honey bees (Fig. 3) .