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ARS Home » Southeast Area » Baton Rouge, Louisiana » Honey Bee Lab » Research » Publications at this Location » Publication #346724
Title: Gamma irradiation inactivates honey bee fungal, microsporidian, and viral pathogens and parasites

Author
item Simone-Finstrom, Michael
item ARONSTEIN, KATHERINE - Former ARS Employee
item GOBLIRSCH, MICHAEL - University Of Minnesota
item Rinkevich, Frank
item De Guzman, Lilia

Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/2018
Publication Date: 2/22/2018
Citation: Simone-Finstrom, M., Aronstein, K.A., Goblirsch, M., Rinkevich Jr, F.D., De Guzman, L.I. 2018. Gamma irradiation inactivates honey bee fungal, microsporidian, and viral pathogens and parasites. Journal of Invertebrate Pathology. 153:57-64.

Interpretive Summary: Despite the fact that honey bee colonies and beekeepers are constantly fighting various pathogens and parasites, there are no widely available universal treatments to allow for the reuse of old wax combs that can harbor these pathogens. In addition there is no commercially available treatment for the numerous viruses that are currently plaguing honey bees. In order to reduce exposure to these threats and to allow for more sustainable reuse of equipment, we investigated the potential of gamma irradiation for inactivation of the larval pathogen of chalkbrood, the gut parasite Nosema, and three honey bee viruses (Deformed wing virus [DWV], Black queen cell virus [BQCV], and Chronic bee paralysis virus [CBPV]). Results indicate that gamma irradiation can effectively inactivate A. apis, N. ceranae, and DWV and greatly reduce or eliminate the ability of these pathogens and parasites to infect honey bee larvae or pupae. Lesser effects were noted for BQCV and CBPV. These findings suggest that gamma irradiation may function as a broad treatment to help mitigate colony losses and the spread of pathogens through the exchange of comb across colonies, but raises the question why some viruses appear to be less affected. These results provide the basis for studies on benefits of irradiation of used comb for colony health and productivity.

Technical Abstract: Managed honey bee (Apis mellifera) populations are currently facing unsustainable losses due to a variety of factors. Colonies are challenged with brood pathogens, such as the fungal agent of chalkbrood disease, the microsporidian gut parasite Nosema sp., and several viruses. These pathogens may be transmitted horizontally from worker to worker, vertically from queen to egg and via vectors like the parasitic mite, Varroa destructor. Despite the fact that these pathogens are widespread and often harbored in wax comb that is reused from year to year and transferred across beekeeping operations, few, if any, universal treatments exist for their control. In order to mitigate some of these biological threats to honey bees and to allow for more sustainable reuse of equipment, investigations into techniques for the sterilization of hive equipment and comb are of particular significance. Here, we investigated the potential of gamma irradiation for inactivation of the fungal pathogen Ascosphaera apis, the microsporidian Nosema ceranae and three honey bee viruses (Deformed wing virus [DWV], Black queen cell virus [BQCV], and Chronic bee paralysis virus [CBPV]), focusing on the infectivity of these pathogens post-irradiation. Results indicate that gamma irradiation can effectively inactivate A. apis, N. ceranae, and DWV. Partial inactivation was noted for BQCV and CBPV, but this did not reduce effects on mortality at the tested, relatively high doses. These findings suggest that gamma irradiation may function as a broad treatment to help mitigate colony losses and the spread of pathogens through the exchange of comb across colonies, but raises the question why some viruses appear to be unaffected. These results provide the basis for subsequent studies on benefits of irradiation of used comb for colony health and productivity.