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American Bee Journal

The Classroom – April 2024

By May 20, 2024No Comments


Keeping sugar water fresh
I have +/- 200 single hives. I pail feed and am running into black mold in the pails. I have heard of putting a teaspoon of bleach in each pail with the sugar water. I do not want to do that as I feel it may harm the bees. I was using 2-gallon (7.6 L) pails but have gone to 1-gallon (3.8 L) pails. Do you have any suggestions?
Peter Lyford
Maine, February

I have received this question frequently in recent years. In fact, I answered a similar question in the December 2021 and January 2023 articles. I paste below my most recent answer (January 2023), given that I feel this continues to be an important issue to discuss.
First, almost all beekeepers who have fed sugar water to bees in glass jars have seen the mystery black scum form on the walls of the jar. I have never seen any research actually determine that this stuff is harmful for bees. However, I am aware that sugar water can ferment, and nothing fermented should be fed to bees. My point is that beekeepers may be trying to control a problem that is not actually a problem [with the black scum]. There definitely needs to be work on this topic.
Second, I conducted multiple literature searches on the topic of adding bleach/chlorine/vinegar to sugar syrup to determine if it keeps sugar water from spoiling and if its addition to sugar water is harmful to bees. I could not find any research projects conducted on this topic.
This leads me to my third point, which is that I would not use bleach or chlorine in sugar water to keep it from spoiling. I am aware that many beekeepers add various concoctions to sugar water in an attempt to keep it from spoiling. I have heard about the use of vinegar, bleach, and other substances. However, I always stress to folks that these are untested methods. You could argue, maybe even rightfully so, that these have been tested in the court of public opinion and that beekeepers have found a way to use these products in sugar water safely. I just hesitate to recommend something that has no data to support it. So, what is a better option?
I recommend feeding colonies only the amount of sugar water that they can consume within 2-3 days. That limits the likelihood of spoilage. I also do not store large amounts of sugar water prior to use. I have always made it “on demand” when needing to feed bees. That way, I do not have large volumes of sugar syrup susceptible to spoilage.
My team and I are interested in determining if the black scum is harmful to bees and how best to control it. Maybe I will be able to provide a research-based answer to this question in the future.

Queen orientation flights
Do queens do an orientation flight before their mating flight? I mean, I would assume they do because they have to find their way back to the box, but maybe they have some other mechanism that helps them find their way.
Kevin Monfelt

They do take orientation flights. I happened to co-author (with Niko and Gudrun Koeniger and Larry Connor) a book entitled “Mating biology of honey bees (Apis mellifera).” I was able to find the passage from the book that deals with queen orientation flights. Here is the quote:
“The first flights of a young queen are normally short, with flight durations averaging less than five minutes. These are thought to be orientation flights during which the young queen learns the location of the nest, and, specifically, of the nest’s entrance. Once she has a good understanding of where the nest is located, the queen leaves for her normal mating flight that lasts 15 to 30 minutes, depending on local conditions.”
I want to elaborate on this for the benefit of the readers of this column. Adult bees (queens, workers, and drones) emerge from their cells naïve about their hive’s location in the surrounding environment. Despite this, bees of all three types leave their hive for various reasons: queens and drones to mate, workers to forage. Foraging and mating do not typically occur immediately outside the hive. Thus, the bees must know how to find their hive before they leave it the first time. They do this by learning the location of their hive through multiple orientation flights.
As the name implies, orientation flights exist to orient the bees with the geospatial position of their hive. The bees will emerge from the hive entrance, fly a short distance from the hive, turn back toward the hive and return to the hive entrance. They do this over and over, with each flight often being a little longer than the preceding flight. The bees are using these flights of ever-increasing distances to determine local landmarks they can use to locate their hive when leaving the nest for foraging (workers) or mating (queens and drones) purposes. Queens do take orientation flights, as they otherwise would not be able to return to their hive after mating.

Can RNAi technology work to control Varroa?
Have you tested the product being developed by GreenLight Biosciences whereby RNA that is detrimental to Varroa is fed to bees in sugar syrup? If so, is it going to be registered in the United States? Does it work?
Andy White
Mississippi, February

I have not tested the current product being developed by GreenLight Biosciences. I am familiar with the science and the history of the product, having worked on the project years ago when the technology was owned by other companies. I have watched the product mature through the years, to the point that it is now. The company is attempting to register it and there may be a product available in the future.
To address the question, “does it work,” is a bit outside the scope of what I am able to answer. I have not seen the data the company is using to support the product’s registration. I assume that it has some efficacy; otherwise, they would not pursue registration. However, I am not sure what that level of efficacy is, meaning that I do not know how much its application reduces Varroa populations in the nest.
Let me provide a general overview of how this technology works. RNAi stands for “RNA interference.” It is often referred to as post-transcriptional gene silencing because it “silences” gene expression after it is transcribed. What does this mean? We all learn in biology class that a gene is a region of DNA that serves as a blueprint, or cellular instruction, for making a protein. For the blueprint to be read, it must first be converted to messenger RNA (mRNA), a process called transcription. To oversimply: A gene within a strand of DNA is transcribed to mRNA and is read to produce a protein.
I teach it this way: Imagine receiving instructions to… (end of excerpt)

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