Synergistic parasite-pathogen interactions mediated by host immunity can drive the collapse of honeybee colonies.
The health of the honeybee and, indirectly, global crop production are threatened by several biotic and abiotic factors, which play a poorly defined role in the induction of widespread colony losses. Recent descriptive studies suggest that colony losses are often related to the interaction between pathogens and other stress factors, including parasites. Through an integrated analysis of the population and molecular changes associated with the collapse of honeybee colonies infested by the parasitic mite Varroa destructor, we show that this parasite can de-stabilise the within-host dynamics of Deformed wing virus (DWV), transforming a cryptic and vertically transmitted virus into a rapidly replicating killer, which attains lethal levels late in the season. The de-stabilisation of DWV infection is associated with an immunosuppression syndrome, characterized by a strong down-regulation of the transcription factor NF-κB. The centrality of NF-κB in host responses to a range of environmental challenges suggests that this transcription factor can act as a common currency underlying colony collapse that may be triggered by different causes. Our results offer an integrated account for the multifactorial origin of honeybee losses and a new framework for assessing, and possibly mitigating, the impact of environmental challenges on honeybee health.
Dipartimento di Scienze Agrarie e Ambientali, Università degli Studi di Udine, Udine, Italy. francesco.nazzi@uniud.it
Francesco
F
Nazzi
Sam P
SP
Brown
Desiderato
D
Annoscia
Fabio
F
Del Piccolo
Gennaro
G
Di Prisco
Paola
P
Varricchio
Giorgio
G
Della Vedova
Federica
F
Cattonaro
Emilio
E
Caprio
Francesco
F
Pennacchio
D000818:Animals; D001516:Bees / Q000276:immunology* / Q000469:parasitology*; D060085:Coinfection / Q000276:immunology / Q000662:veterinary; D006790:Host-Parasite Interactions / Q000276:immunology*; D007304:Insect Viruses / Q000276:immunology; D008924:Mite Infestations / Q000150:complications / Q000276:immunology / Q000662:veterinary*; D016328:NF-kappa B / Q000276:immunology; D012327:RNA Virus Infections / Q000150:complications / Q000276:immunology / Q000662:veterinary*; D012328:RNA Viruses / Q000276:immunology; D060888:Real-Time Polymerase Chain Reaction; D057077:Varroidae / Q000276:immunology
D016328:NF-kappa B