Spring mortality in honey bees in northeastern Italy: detection of pesticides and viruses in dead honey bees and other matrices



In spring there is often a rise in honey bee mortality incidents. The aim of this study was to investigate the potential
correlation, in the reported incidents, between exposure to pesticide treatments and virus infections. Here we summarize
the situation in northeastern Italy during spring 2014, evaluated by monitoring 150 active ingredients and three
honey bee viruses in dead honey bees and other matrices. At least one active ingredient was found in 72.2% of the 79
dead honey bee samples, with the most abundant (59.4%) being insecticides, mainly belonging to the class of neonicotinoids
(41.8%), followed by fungicides (40.6%). Imidacloprid, chlorpyrifos, tau-fluvalinate, and cyprodinil were the most
frequently detected active ingredients. Multiple virus infections were monitored, revealing a high prevalence of chronic
bee paralysis virus (CBPV) and deformed wing virus (DWV), detected in all samples except one. 71 and 37% of the
CBPV- and DWV positive samples, respectively, showed a high number of viral copies per bee (>107). This work
emphasizes the possible relationship between spring mortality in honey bees and pesticide treatments. Honey bee
viruses could synergistically exacerbate the negative impact of pesticides on honey bee health, endangering the survival
of colonies.

 

Martinello M., Baratto C., Manzinello C., Piva E., Borin A., Toson M., Granato A., Boniotti M.B., Gallina A., Mutinelli F. Spring mortality in honey bees in northeastern Italy: detection of pesticides and viruses in dead honey bees and other matrices. Journal of Apicultural Research, 2017, 56(3), 239–254.