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  • From: Randall Austin <ra41717 AT gmail.com>
  • To: Catherine Wright <catherine.wright AT gmail.com>
  • Cc: ocba AT lists.ibiblio.org
  • Subject: Re: [ocba] nosema questions
  • Date: Mon, 06 Apr 2015 15:13:08 -0400

Catherine,

Your question sparked my curiousity, because while I know nosema spores aren't virtually indistructible the way that American Foulbrood spores are (and they are different type creatures, anyway), I didn't know how long they'll live outside of a bee's body. I found this posting by Eric Mussen, who recently retired from UC Davis as California's state apiculturalist and is a person to be listened to:
The spores of both nosema species are susceptible to irradiation or fumigation with glacial acetic acid (details in The Hive and the Honey Bee). Otherwise the spores of apparently Europe-originated N. apis are very resistant to the elements, except sunshine, and persist for many years. Nosema ceranae, on the other hand, originated in tropical Asia, and its spores are susceptible to weather, especially cold weather. The spores can be killed by refrigeration or by freezing. If possibly spore-contaminated combs are placed in a freezer and left there until it is certain that all materials in the combs have reached freezing temperatures (honey holds a lot of heat for quite a while), N. ceranae spores, all life stages of greater wax moth, all stages of small hive beetle, and other little critters that tend to get into stored combs will be eliminated.
A few things to note:
  • Dysentery is a symptom of nosema but nosema isn't the only thing that can cause dysentery.
  • The spores are spread when bees feed other bees with infected food or bees clean up poop that has spores in it.
  • Nobody is bothered by a little nosema. It becomes an issue when the number of organisms increases beyond a healthy threshold.
  • A strong, healthy hive will keep nosema under control without any help from us. It is usually a nuisance disease, like the flu in people. Yes, the flu can kill people but typically it only kills the elderly and the immuno-compromised. Otherwise we get over it.
  • Recent evidence & research strongly suggests that the cure (fumidil-B aka fumigillin) can be worse than the disease, particularly for nosema cerana.
So -- I would certainly believe Dr Mussen and take the precaution of freezing the frames for a few days, then to make sure you take care of either type of nosema, put them in the sunlight for a few days. Then they should be good to go. Beyond that, don't give nosema a second thought. Focus on keeping varroa mite infestations very low -- varroa is the root cause of poor health and weak colonies, opening the door to other problems.

Randall Austin

On 4/6/2015 1:10 PM, Catherine Wright wrote:
Hi everyone:

I have a question about nosema. My family installed hives for the first time last spring. One survived the winter. The other had very small numbers going into winter and did not survive. We found signs of defecation on four frames from this hive. A small cluster of dead bees were on two of these frames where brood was emerging. Most dead bees were on the bottom board. Some were in the top feeder in syrup. My question is: Do the signs of defecation inside the hive signal nosema? If so, what do we do with the frames/comb and honey/pollen?

Thanks,

Catherine



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