Over the years, my sons, assistant inspectors and commercial beekeepers alike have commented that I only get enthusiastic working bees when we encounter “bad stuff.” I immediately refute such comments, but must confess that they are true to an extent. Bad stuff like American foulbrood, pesticide kills and bears irritate rather than excite me, while the sight of bees hauling in nectar is exciting every time. Truth be told though, my curiosity and interest are piqued when a new parasite, pathogen, problem or crisis is encountered. Having opened and inspected many thousands of hives, the situation need not be unprecedented, but just new to me.
In September, a beekeeper called to report that one of his hives had a severe case of nosema with feces streaking down the front of the brood chambers. If this report had come during late winter or early spring, it would be routine, but September is another matter. I asked the usual questions.
Are bloated bees crawling in front of the hive? Is the colony being fed an unusual source of sugar syrup such as molasses, maple syrup, Tang or Coke? Are the bees visiting water sources that could be contaminated from sewage, a nearby processing plant or industrial runoff? The answer was “no” for all.
Fortunately, I had another inspection of migratory hives scheduled in the same county the following week. Otherwise, I may not have taken the ride and simply concurred that it was nosema.
The apiary had six hives and sure enough, one of them had very dark feces streaked on the hive bodies. Note: It is normal to see yellowish feces on top or in front of hives after bees have been confined due to rain for a period, especially when rearing brood. Flight activity appeared to be normal and no bees were found dead, trembling or crawling in front of the hives. The beekeeper had commenced feeding syrup medicated with fumagillin and the bees were taking it. My instincts were that it wasn’t nosema and I again asked if there was a potential of contaminated water nearby. The contaminated water theory was weak since only one hive had symptoms. But you never know. Also, the fact that the bees were consuming syrup also suggested the cause for acute dysentery wasn’t nosema.
We sampled the sick hive and one of the strong, productive hives. Varroa was present in both, but not at a critical level, due to a summer mite treatment. I couldn’t wait to process the nosema samples the following day.
The first thing I noticed when preparing the sample (by crushing bee abdomens) from the sick hive was a strong putrid odor which hasn’t been common among the thousands of samples I’ve checked over the years. My immediate thought after getting a whiff was septicemia. However, the bees didn’t fall apart, which is a common symptom of this bacterial infection that damages connective tissue. The “healthy” hive had a normal odor and tested negative for nosema. The hive with acute dysentery did have nosema at a very low level (100,000 spores/bee), which is well below the current treatment threshold of 1,000,000 spores/bee. In fact, I have seen many hives with spore counts in excess of 20 million spores/bee without dysentery symptoms, even during winter. I did see amoebas.
I called the USDA Bee lab for insight. Yes, the lab has seen a few samples with amoeba infections and they too noticed the putrid odor when preparing the samples. There are no recommendations for treatment since the condition is neither very common, nor of economic importance. Antibiotics such as tetracycline aren’t effective in killing these single-cell organisms. I have communicated with the beekeeper and he reports the dysentery has not worsened. I had no advice for him other than to continue the fumagillin and to consider dusting with Terramycin even though it won’t kill amoebas.
Apparently, my boys and the commercial beekeepers are right.