At the risk of asking a dumb question – has anyone come across research that indicates Nosema parasitizes Varroa mites?

I ask because I’ve seen a couple of studies suggesting large Varroa populations suppress Nosema populations and vice-versa. 

The first such study, published in 2016, reviewed results of the U.S. National Honey Bee Disease Survey from 2009 to 2014. 
(“Multiyear survey targeting disease incidence in US
honey bees” by Kirsten S Traynor et al.)

In the discussion section of this paper the author wrote:

“Interestingly, stationary and migratory beekeepers
varied significantly in their Nosema and
Varroa levels. Stationary beekeepers tended to have
higher mite infestations and lower Nosema spore
loads, while migratory beekeepers showed the opposite
trend. Migratory beekeepers may be treating
more frequently to reduce Varroa populations, or
the physical movement of trucking bees for pollination
may be interfering with mite reproduction.”

Agriculture and Agri-Food Canada conducted a similar beekeeping health survey from 2014 to 2017. See:

 https://www.gprc.ab.ca/research/initiatives/nbdc/projects/current/nat_survey.html

The final results have not yet been published, but in March of this year, all survey participants were sent a report (“Canadian Honey Bee Health Survey 2014-2017”, by Dr. Nabil Maarouf) outlining the study’s initial findings. Dr. Maarouf's report included the following statements:

“The significant presence of one of the 2 parasites (Nosema or Varroa) in a hive protects in
most cases against an important infestation of the same hive by the other parasite (Varroa or Nosema, OR=0.6, χ²=9.8, p=0.002).”

“The Varroa load is less higher in Nosema group (Difference=0.7±0.2, F1,939=13, p<0.000) while
the Nosema load is less higher in Varroa group (Difference=530000±150000, F1,939=21, p<0.000)”

“The opposed relation between Nosema and Varroa is also verified geographically inside the same provincial regions.”

If in fact Nosema and Varroa act as kryptonite for each other, the possible benefits from learning the details of this relationship are obvious. 

In her U.S. Survey paper, Dr. Traynor discusses several possible scenarios that might explain how these two pathogens are linked. But nosema infecting varroa was not one of them. Could this be possible?

The Canadian survey samples were collected in late August/early September before fall mite treatments were applied. Hives were not tested for miticide residue but it seems unlikely they were a factor given the sample window.

BTW, I live on a distant spiral arm of the galactic beekeeping universe so don’t have a clear view of what takes place there in the center of everything, but I assume the author of “Multiyear survey targeting disease incidence in US honey bees” is the same Kristen Traynor who is now the editor of ABJ. 

I was appalled to read some of the recent comments concerning Dr. Traynor on the “ABJ Disclaimer” thread. What the heck? Do we not want more scientists trained in beekeeping to participate in our “Informed Discussion of Beekeeping Issues and Bee Biology”?

 Constructive criticism is part of a healthy debate but should not be used as cover to inform people their participation in this discussion group is not welcome – which I suspect is the message Dr. Traynor recently received. At least that’s my view from this distant vantage point. I appreciate Dr. Traynor’s efforts to improve our knowledge of bees and beekeeping and hope she will continue to participate in these discussions.

Thinking some degrees are good. More are better.

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html