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Nosema and dysentery are not the same

Yesterday I read the following statement on the blog of a well-known beekeeper. “First I looked at the hive entrances which had signs of nosema the last time I visited. The hive looked just the same – no new nosema on the side of the hive.”

Whoa! There are at least two things wrong with this statement. First off, you cannot see Nosema on the side of a hive. What you can see on the side of a hive is bee feces, which may or may not contain Nosema. More often than not, an accumulation of runny brown feces at the entrance to a hive in spring is honey bee dysentery. Unlike human dysentery, honey bee dysentery is not caused by a pathogen but by poor diet.

It is true that Nosema apis also causes diarrhea-like feces to be deposited in or on the hive, but it cannot be distinguished from dysentery without a laboratory analysis—or at least a microscope and some training.

Secondly, Nosema ceranae, which also can infect honey bees, does not cause the bees to defecate in or on the hive. Most often bees become infected with Nosema ceranae in the summer and die in the field while out foraging. In any case, bees infected with Nosema ceranae do not leave diarrhea-like feces as a clue.

In summary, seeing no feces does not mean the bees are free of Nosema anymore than seeing feces means they are.

Rusty

Comments

Doug
Reply

I wonder if Fumagilin has any affect on Nosema ceranae? I haven’t found anything with a solid, conclusive, yes or no, yet. Some say yes. Some say no. Some say a little and I still don’t know. Are there any scientific papers on this? I can’t seem to find them if there are.
They say the bees will overcome Nosema A, if you let them deal with it. They need to have it, to beat it, without treatment. They can’t beat Nosema C, from what I understand. If Fumagilin treats Nosema C, even a little, then treating is a must.
I guess I’m just not that daring yet. If I caught a serious bug, that could kill me, I would drink my Fumagilin.

Rusty
Reply

The things I’ve read about Nosema are just as you say. The bees can beat N. apis but not N. ceranae by themselves. Some say Fumagilin-B works for N. ceranae and some say it works partially or not at all. Some say it requires larger doses, but no one has said (as far as I know) what those larger doses are. I don’t know anymore about this than you do.

Darwin Deming
Reply

Does regular bee dysentery in the spring need to be treated or will the bees overcome it on their own as temperatures warm and they are able to spend more time out of the hive? I do try to clean up what I can to get the feces out of the hive.

Rusty
Reply

Darwin,

Yes, usually honey bee dysentery clears up by itself once the bees start flying and have a spring diet. I do the same thing—clean up the best I can and call it good.

JennFive
Reply

Thanks for confirming the possible confusion. I am a first timer, and I wasn’t sure what to think when after the first couple days of sun, the front of my hive was covered. We haven’t had great weather to open the hive up and really inspect. Sounds like I am ok to assume spring dysentery…unless the dysentery doesn’t seem to improve?

Rusty
Reply

Jenn,

It can be confusing, but if it clears up quickly, it was probably dysentery. Also feces that is brown and runny should quickly change to yellow globs that sort of hold their shape. Nosema apis can sometimes clear up on its own as well, but not as quickly and sometimes with significant bee loss.

Bridgett
Reply

I am a first year beek. I have my first over-wintered hives. I had two colonies. One colony turned out to have massive streaking and tons of dead bees. The hive right next to it was completely clean. This summer my clean hive is busy, lots of pollen coming in on sunny days. In North Central Idaho we’ve just began to have days that are warm enough to crack open the hives. My “streaked” hive had a few bees coming and going, all without pollen. I suspect they are neighboring bees robbing the stores of the slow (or dead) hive. I opened up my slow dirty hive, and no bees were there. They died, ug. I feel terrible. Can they die from dysentery? We’ve had such a long cold winter. They still had plenty of honey stores. Can I eat that honey? Can I feed it to my good hive?

Rusty
Reply

Bridgett,

Bees can die of dysentery but I suspect yours had Nosema apis. I wouldn’t feed the honey to new bees unless you first had the dead bees tested for Nosema. If they didn’t have Nosema, then it’s fine for feed. You can eat it in any case because humans don’t get Nosema. However, before you extract it, make sure you clean the feces from the combs. I would use a wash of bleach water, gently applied to the combs and then allowed to dry.

As for cleaning up the equipment, this may help: How to clean up after Nosema apis.

Bridgett
Reply

Thank you so much, I will go forward as if Nosema is present. Also, do you know of a colleague, someone who knows honeybees at University of Idaho? If not, I can call the entomologist there. I am a Vandal too. Thanks again Rusty.

Rusty
Reply

Bridgett,

Sorry, I don’t know anyone at the University of Idaho.

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