Multifaceted responses to two major parasites in the honey bee (Apis mellifera).

The recent declines in managed honey bee populations are of scientific, ecological and economic concern, and are partially attributed to honey bee parasites and related disease. McDonnell et al. investigate behavioral, chemical and neurogenomic effects of parasitization by the ectoparasite Varroa destructor and the endoparasite Nosema ceranae. The study reveals important links between underlying mechanisms of immunity and parasitization in social insects by demonstrating that chemical signals and neurogenomic states are significantly different between parasitized and non-parasitized honey bees, and that neurogenomic states are partially conserved between bees infected with distinct parasites. However the study does not reveal whether differences measured are primarily the result of adaptive host responses or of manipulation of the honey bee host by the parasites and/or confounding viral loads of parasitized individuals. Questions answered and raised by McDonnell et al. will lead to an improved understanding of honey bee health and, more generally, host-parasite interactions.