Hi all
I have heard from many sources that bee viruses degrade rapidly outside their hosts and used equipment therefore would not be a serious source of virus infection. This work from ten years ago seems to directly contradict that notion. 

Test of infectivity of virus in stored pollen and honey 

In Fall 2005, frames of bee bread (stored pollen) and honey were collected from colonies previously determined to have DWV (both from symptoms and with RT-PCR). Multiple cells of bee bread or honey were sampled at random from both sides of each frame and RNA was extracted from groups of 2–3 cells. RT-PCR was performed for DWV, SBV, and KBV. Only DWV was detected in the majority of the cells both for frames of honey or bee bread. These frames were stored at ambient temperature over the winter (fluctuating from below 26uC to 32uC), with protection from pests. Additional frames were power-washed to remove all deposits, leaving some wax; these were designated as ‘‘clean’’ frames. The wax did not have DWV as tested by RT-PCR.

Six months later in Spring 2006, new packages were placed into new hive equipment in an isolated apiary (Rock Springs Apiary) that had no known feral or managed colonies of honey bees located within 8 km. The surrounding area was forest, meadow and farmland. After one week when the colonies had established and the marked queens had begun to lay eggs, egg samples (N= 4 samples of 5 eggs each, or 20 eggs per colony) and worker attendants (N = 15) were collected for each colony and analyzed for DWV, BQCV and SBV. A total of twelve packages or colonies were found to have workers free of DWV, KBV, and SBV; and the queens were laying virus-free eggs.

These packages were randomly divided into three treatments with four colonies each: Controls (fed artificial bee pollen and sugar syrup, given ‘‘clean’’ frames), DWV-Honey (fed a frame of honey contaminated with DWV and artificial bee pollen), or DWV- Bee Bread (fed a frame of bee-bread contaminated with DWV and sugar syrup). Egg samples from each colony (N= 4 samples of 5 eggs each, or 20 eggs per colony) were collected every week for five weeks following introduction of the frames of food; and DWV and SBV infections and actin were determined by RT-PCR. Each marked queen was observed in its colony during the experiment, ensuring that the same individual queens were being monitored for viral infection.

DWV was not detected in egg samples from all 12 colonies for the first week following introduction of the frames of virus contaminated bee-bread, honey, or ‘‘clean’’ frames (Figure 4). At week two, three out of four colonies fed virus-contaminated beebread were found to have queens laying eggs with detectable DWV; in subsequent weeks, the percentage of the egg samples infected with the virus increased in these three colonies. With a delay of one week, a similar pattern was observed in colonies fed with DWV-contaminated honey, with three out of four colonies having eggs positive for DWV. Only one control colony had a few DWV infected eggs by weeks four and five. The percentage of colonies infected with DWV over time was significantly higher in treatments where either contaminated bee bread or honey was fed as compared with controls. This indicated that DWV virus in the stored pollen or honey was infectious, even after storage in a pest free building at ambient outdoor temperature (fluctuating from approximately -6C to 32C) for six months.
 
Citation: Singh R, Levitt AL, Rajotte EG, Holmes EC, Ostiguy N, et al. (2010) RNA Viruses in Hymenopteran Pollinators: Evidence of Inter-Taxa Virus Transmission via Pollen and Potential Impact on Non-Apis Hymenopteran Species. PLoS ONE 5(12): e14357. doi:10.1371/journal.pone.0014357

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