nosema spore count?

[rober]

I sent 2 dead-outs to the usda last feb. finally heard back. no trachea mites, low varrora count, & 4 million nosema spores per bee. the usda guy had no answer & I can't find anything online. how many spores per bee is too many????

[buzzbee]

Maybe this will help:
"For Nosema apis, the treatment threshold was considered to be a mean spore count of 1M per bee.  On the other hand, there is considerable debate as to what constitutes a worrisome spore count for Nosema ceranae.  At the time of this writing (9/16/2011) a few million spores (up to about 25 in a field of view) would be considered by many to be “normal” for field bees for much of the season, perhaps spiking to several million (100 or more spores per field of view) during spring when there are heavy pollen flows, but then dropping to near zero during summer.  I cannot make recommendations, but post the latest information at ScientificBeekeeping.com."
Here is the link:
http://scientificbeekeeping.com/sick-bees-part-13-simple-microscopy-of-nosema/
This may also be helpful:
http://entomology.ucdavis.edu/files/147621.pdf

[rober]

I asked the contact at the usda & was told their tests don't say which type of nosema spores were present which I thought was odd. is not nosema ceranae the most common form of nosema these days? also this was a winter deadout that occurred in jan. or feb. so that's when the count should be calculated. thanks for the links.

[Michael Bush]

Nosema apis is virtually extinct.  It's been replaced by ceranae.

[rober]

I just got an interesting reply from the usda. the rep says that when treating nosema ceranae with fumigillin B that spore counts will drop but often there is a rebound effect 2-3 weeks later & the spore count can double or triple what it originally was. I do not believe i'll be treating for nosema any time soon unless I find spore counts way over the limits ( if I can ever find out what constitutes an excessive spore count).

[Michael Bush]

Yes, the latest research shows that Fumigillan makes Nosema ceranae worse... probably because it kills off the beneficial bacteria that protects the bees from Nosema...