Colony postmortem #4: two losses in one week
Here’s a new postmortem for all of you bee sleuths out there. Jim Metrailer from Alabama sent the following pictures and questions with the go-ahead to share them with you.
The first colony
On January 25th, a sunny day with temperatures in the mid-50s, Jim inspected his hives. His top-bar hive and one Langstroth showed activity, but the other Langstroth was completely inactive, showing no signs of life.
Upon opening the hive, he found no bees in the honey super which was situated above a queen excluder. The super itself was well-stocked with honey.
In the brood box below, he found the marked queen, torpid and alone. A few dead bees had accumulated on the bottom screen along with some small hive beetles. The brood box contained lots of honey and pollen. The nest contained capped brood, eggs, and larvae, and a small amount of feces was visible on the frames.
Jim noted that the bees in this hive were fed Honey-B-Healthy in their fall syrup, and that back in June this hive had a large number of dead bees in front of it.
- Could this situation be caused by Nosema apis? He theorized that the pathogen could have reduced the population to the point where the colony could no longer keep itself warm in winter.
- Should the dead bees be examined for Nosema?
- How might the brood box frames, honey, and residual brood be used?
- How should the equipment, the box itself, and the bottom board be handled?
- How can the honey frames in the super above the queen excluder be utilized?
- Any other thoughts or suggestions?
The second colony
Then, on January 31, I received an update from Jim. The second Langstroth was now showing no sign of activity and, upon opening, no bees were present. The hive still contained plenty of honey. On a side note, the top-bar hive was still showing lots of activity.
Jim’s new question is, “What did I do wrong?”
At this point I was able to gather a bit more information:
Neither of the dead colonies were treated for varroa because mite counts had shown an infestation rate of less than 1%. The second colony to die was also supposed to be varroa-resistant. Jim uncapped some of the brood and found no varroa. These colonies were both quite populous in the autumn.
The top-bar hive in this same location was also not treated. Jim also has two top-bar hives in another location that are doing fine. One, started from a package, was treated with Apivar, and the other, started from a swarm, was not.
My thoughts and observations
I suppose this set of conditions could be caused by one of the Nosema pathogens, although in lots of areas N. ceranae has replaced N. apis, so I think the former is more likely. I think the small amount of feces shown in the photo is a red herring. It’s such a small amount that it could have been released by a bee with bad timing. Furthermore, although Nosema apis and dysentery often correlate, Nosema doesn’t cause dysentery. Even if the bees got into some watery feed, it sounds like they’ve had enough fly days to take care of it. I also think the number of small hive beetles is a non-issue.
Often, if the queen has Nosema, you see some queen cups in the remaining brood patch, which are obviously not here. Queen cups, though, are not mandatory.
The small number of bees on the bottom board suggest to me that, until recently, the undertaker bees were still carrying out the dead. Alternatively, the bees, knowing they were sick with something, were performing altruistic suicide, flying away to die remotely. Also, in my experience, the dead seem to pile up more with Nosema than they do with varroa—not sure if that’s a fact or not.
The shot brood photo is hard to read. Shot brood (a brood pattern that looks like it’s been hit with a shotgun) can arise from several things. It can result from an inbred queen, AFB, or varroa, and probably other conditions as well. I doubt it was an inbred queen because she was doing well until now.
Holes in the cappings
One thing I do see is some caps with holes that often arise along with varroa mites, but they also appear with AFB. I don’t see any additional signs of AFB, however, such as scales with tongues or dark cappings. It would be helpful to know if any odor accompanied the brood nest.
The close-up photo is pretty interesting. If I’m seeing any mite frass, it’s not predominant. The dead larvae are dark, which probably means they got chilled and died, which makes sense. The odd thing is the eggs. The eggs appear to be single, centered, and tipped over, which indicates they were laid by a queen and not laying workers. This queen appears to have remained active until just a day or two prior to the photos, and until recently she was still laying fertilized eggs.
Things that make me think of varroa are:
- Honey remaining in the hive
- Most bees are gone, a possible indication altruistic suicide
- A small patch of brood remains, accompanied by a queen until recently
- The collapse occurred in late winter
- These were large colonies going into fall (large populations tend to collapse faster from varroa than small ones)
- Although varroa numbers were low in fall, I don’t know the protocol for counting (sorry, I didn’t think t ask)
I don’t know the answer
In spite of all that, I don’t know the answer. I lean toward varroa, but that’s based just on the things I can see and not those I can’t, so I’m eager to see what everyone thinks. I know that Jim will appreciate any insight you have.
Honey Bee Suite