Our analyses indicate that the basic set of molecules defining the insect host-defence system is present in honey bees, including intact pathways for the key processes implicated in immunity and development. Single orthologues can be assigned for many pathway members, while others show several potential bee genes for which further work is needed to confirm roles. Interestingly however, whereas in Drosophila and Anopheles the host appears to have diversified its molecular arsenal through species-biased gene duplication (Table 1) , we have not found examples of such gene expansions in honey bees. Thus, despite having wideranging parasites and pathogens, and tremendous losses to these pests at least in domesticated settings (Morse & Flottum, 1997) , bees appear to have relatively diminished capacities to respond to and defend against pathogens.