Pathways of Dispersion of RNA Viruses that Affect Honey Bees

REYNALDI, F.J.; SGUAZZA, G.H.; GENCHI GARCIA, M.L.; LUCIA, M.; BRAVI, M.E.; PECORARO, M. R.; GALOSI, C. M

Estambul

Congreso; 45th Apimondia International Apicultural Congress; 2017

Honey bees and wild pollinators, contribute to the pollination of natural and industrialized crops. Recently, multiple cases of depopulation of beecolonies have been detected at the end of winter. Different factors seem to contribute to these reduction of bee populations, such as severalpathogens, changes or losses of their ecosystem, and the use of agrochemicals. All these factors alter the defense mechanisms of the immunesystem, and the viruses circulating take advantage of this situation in the colony generating disease.The objective of this work was to study the possible routes of viral dispersion in colonies of honey bees.We used 25 bee colonies that were not treated for V. destructor in the last year. After a year without acaricide treatment, in summer of 2015 thepresence of V. destructor was quantified, samples of bees and mites were collected and the colonies were treated with commercial acaricides.Three samples were then taken in the autumn and winter of 2015 and summer of 2016. An mPCR RT was performed with bees and mitescollected to detect 7 viruses. In the 4 sampling periods, 2 wild pollinator specimens (Bombus atratus and Xylocopa augusti) were also sampled.At the beginning of the trail 100% of the hives had V. destructor (mean infestation level 11.85%). In autumn, after treatment with coumaphos,10% of the hives were infested (3% of infestation level), in winter mites were not detected. In summer of 2016 60% of hives were detected witha mean infestation of 1.03%.Presence of viral agents in samples fluctuated independently of the amount of mites recorded. In wild pollinatorsSVB, BQCV and DWV were detected.We concluded that there is a relationship between the mite and the presence of certain viruses such as DWV or CBPV. Mites and pollinatorscould explain the fluctuation of some viruses. However, other viruses such as ABPV or BQCV were not detected in varroa or wild pollinators,increased their incidence in the absence of these possible vectors.The study and understanding of the viral dispersion mechanisms in hives would allow us to designing alternatives for viral management.