Barrier Immune Effectors Are Maintained during Transition from Nurse to Forager in the Honey Bee
Foragers facilitate horizontal pathogen transmission in honey bee colonies, yet their systemic immune function wanes during transition to this life stage. In honey bee systemic immunity, antimicrobial activity has been shown to decrease in the hemolymph of foragers relative to nurses. To begin to correlate microbe levels and immune parameters in our study, we examined the levels of microbe-specific RNA from various known honey bee pathogens [35], including Nosema apis, Nosema ceranae, Ascosphaera apis, Crithidia mellificae, DWV, BQCV, SBV, Paenibacillus larvae, and Melissococcus plutonius in pooled samples from all trials. Our data provide the first evidence of inducible AMP expression in the barrier immune system of the honey bee. Specifically we found a positive association between N. ceranae levels and the quantity of two AMPs, Abaecin and Apidaecin. We also found a positive correlation between the relative amount of DWV and the AMP Apidaecin.