Varroa Isn't the Only Reason Why Your Hive Absconded this Fall..
Over the last few weeks I have noticed a surplus of facebook posts that go something along the lines of "Bees left this past weekend. Had 3 boxes on. Had plenty of resources and honey. I used mite strips earlier in season. Why'd they leave?" or "The bees left, have eggs on 2 frames, no pests, inside looks good.. While inspecting hive, the queen lands on a frame and climbs back in hive no workers in sight. Any suggestions?" and "Quick question about bees: 3 of my 5 strong Russian Hives left over the last few weeks. Taking all their honey & their larvae. What happened?"
In November, it's common for hives to start absconding (leaving the colony). But this is the big head scratcher that beekeepers have been trying to figure out over the last decade. We have coined a blanket term for it, Colony Collapse Disorder (CDC). Colony Collapse Disorder (CCD) is a phenomenon honey bee colonies have a sudden and unexplained loss of a majority or all of the worker bees in a hive. In some cases they will leave behind the queen, immature bees, and a small number of nurse bees. But in other cases, they will leave behind an empty box with capped brood and some resources (bee bread and honey) they couldn't carry with them.
If you scroll through the comments on these posts you'll see that 90% of the responses mention high varroa levels being the culprit. Which CDC didn't appear until varroa appeared but is there more to the picture on why your colony may have died?
What happens when a hive collapses from mites?
Month 1-2: First you have a strong and vibrant colony, they're racking in honey and pollen, going flower to flower to collect all that they can. This is where the infestation begins. Mites are transferred from bee to be at foraging sites and amongst partnering colonies in a yard or near by.
Month 3-4: The mite population begins to increase. Mites utilize brood cells to reproduce and can make 1 to 2 daughters in every worker bee cell. But, drone cells have the potential to produce 2-4 mites per cell because drones have a longer development time, allowing more daughter mites to mature before the new bee uncaps and emerges from the cell.
Month 5-6: As each cycle of brood replicates more and more mites, the development of new bees begins to be affected. Newly hatched mites feed off of the developing honey bee larva, weakening the newly forming baby bee and depriving it of nutrients and weakening it's immune system. At this stage you will begin to notice that you hive population will begin to go down. Foragers will become less effective as they don't have the necessary nutrients to support their flights and viruses will begin to overtake their health.
Month 7-8: Because the foragers weren't able to be productive in the previous month, the hives food stores begin to drop. The nurse bees begin consuming eggs to help conserve food. This is when a spotty brood pattern will begin to appear. You will also notice sick looking brood. Some that may appear melted, laying flat on the side of the cell. You will also noticed uncapped brood cells where you can see the white heads of developing baby bees and other with their heads chewed off.
Month 8-9: If the mite infestation remains unchecked (often time at this point it is already so far gone that it is hard to recover a hive in this state) the hive will begin to collapse entirely. The few remaining bees that are left in the hive after this stage will abandon the hive in search of healthier living conditions, leaving behind the queen and a small number of immature bees. (They often join surrounding hives, but remember these bees still have mites on them so now they will be taking those mites to other hives...)
See chart on varroa and honey bees over the year.
As you can see in the graph, as winter approaches varroa levels become unbearable as almost every bee in the colony now has a mite on it.
This last year of beekeeping for me was probably one of my most eye opening years. This was the year of skipped flows from poor weather and many flowering trees just decided to skip this years bloom all together. I did not for see this coming and when we would have normally had our black locust flow, I made some splits for increase with the expectation that I wouldn't need to feed them because our black locust flow would help them build up nicely. Not to mention, I was also trying out a new yard location which appeared to have a large number of flowering plants but looking back that yard struggled to bring anything in all year. Well, it's safe to say that what I had planned did not take into account either of these factors. Many of my hives seemed to have just stopped growing and in fact their numbers began to dwindle. I saw what a starving colony truly looked like from start to finish.
Two years ago I posted a video on Youtube of some of the research articles I was reading around honey bees and varroa mites. Around this time researcher, Dr. Samuel Ramsey, published a new discovery proving what we knew about varroa mites wrong. We originally thought that varroa mites were feeding on the hemolymph (blood) in a honey bee's body. Well, what Dr. Ramsey found was that actually varroa mites weren't feeding on hemolymph but instead they were thriving off of the fat body of our honey bees. To go more in depth, a honey bees fat body is essential for maintaining longevity especially in winter bees. It contains the protein vitellogenin which is responsible for immune function, brood development, it signals the transition from nurse bee to a forager, and it is what keeps winter bees alive for up to 6 months rather than the usual 4-6 weeks of summer bees. This got my wheels turning, as from the sounds of it, varroa mites are feeding off of the one thing that keeps honey bees alive and healthy throughout the winter.
So what promotes higher levels of vitellogenin in honey bees?
POLLEN! This is what I learned from a blog post by Randy Oliver at the scienceofbeekeeping.com. In this article he indicates that every time the pollen supply drops, vitellogenin plummets. And, "the lower the bees vitellogenin titer drops, the longer it takes the colony to recover." Imagine how long it would take for one of us to recover our fat stores, vitamin and nutrient levels, mental clarity, and energy if we were to become infected with a parasite feeding off of the life force of our body. But, I mention pollen because as our local climates keep changing over the last couple of decades, golden rod and other late summer/fall pollen sources have began to dwindle. Hobbyists with a few hives in a yard may never need to feed their hives, but once you start getting to 24 or more colonies in one location, those bees are going to compete even in you have a good flow going on for a week or 2. The bees will go through 3-4 pounds of pollen per week. This means that they need to be able to bring in pollen throughout the duration of the bee season. Otherwise, in hive stores will begin to drop. Nurse bees feed on the pollen coming in so that they can feed it back to the developing brood as brood food. What is left after that gets fed back to the foragers as their reward for a good day. But, if in hive pollen/bee bread stores begin to drop, the brood is prioritized first before the foragers. Thus, leading to the foragers having less energy to search for food and their vitellogenin starts to plummet. The hive begins to appear stressed and the nurse bees will begin cannibalizing eggs in efforts to slow down the consumption of in hive stores. Vitellogenin drops across the whole hive, including the developing brood because their isn't sufficient protein to keep them going. Not counting what the varroa mites are doing to the bees and brood.
From what I saw across my starving colonies this year, once food stores drop, the colony begins falling victim to other pathogens in the hive, EVEN if the varroa mite levels are low. At first I was fairly confused by what I was seeing. My first thought when I started seeing sick brood and spotty brood patterns was that maybe my varroa mite levels were fairly high. But, after performing a mite wash, I found that my hives were sitting at only a 1% infestation rate. I timed this mite wash for a period when brood was emerging in the hive so that I would get a more accurate reading (also pulling my samples directly from frames with emerging brood). At this point I was starting to see what looked like EFB (European foul brood) in my hives. So then began my search to try and figure out what I needed to do to save the colonies in this yard. In my search I began asking other long term beekeepers both those with 100 hives and others with thousands of hives what they knew about European foul brood. To the understanding of the group, the spore forming bacteria that causes EFB is always present in the hive. But, the reason you don't normally see it show up in a colony is because the hive is strong and unstressed. It is well known that honey bees can fight off and maintain viral and bacterial infections on their own IF that hive is healthy. Meaning, they have adequate food stores and/or have enough resources coming into the hive to support their growth. But, once that nutrition begins to drop, vitellogenin follows suit and remember vitellogenin is responsible for immune function. So the bees become vulnerable to pathogens in the hive and viruses that the mites are giving them. Let alone the mites are continuing to feed off of the bees vitellogenin so eventually the hive becomes so weak that it collapses.
Now I am telling you this in reference to varroa mites being the cause of why your bees absconded this fall because in my brain this all looks like it is connected. As a general practice, most beekeepers pull their cut of honey off of their hives in July-September. I have even seen some wait until October to begin pulling their crop for the year. But, at a time when resources are dwindling in the bees environment, I wonder if this may be part of the problem. At least for when it comes to the hobbyist or sideliner who may not be planning on feeding their hives after they pull their honey. And with the smaller golden rod flows we have had over the last few years and in some areas reporting no pollen or nectar flow at all, how does this effect the developing winter brood rearing that generally begins in August? I have noticed from speaking to other beekeepers that have been around since before the early 2000s, the natural resources in our bees environment are starting to decrease as land is deforested into corn, soy, and industrial property. I was not intending for this posting to turn into an article about why feeding your bees in the late summer/fall may be important but these are the thoughts and connections that have been going through my brain. And knowing that pollen will increase vitellogenin stores in a bees body, the exact protein that varroa feeds off of, do you think that feeding pollen as a way of preparing for winter may be essential for you colony's winter health and could be a way of helping the bees overcome varroa?
WHY Did YOUR Bees Disappear?! Maybe Varroa Isn't The ONLY Reason... Beekeeping 101 #beekeeping https://youtu.be/5YscNyT5mfQ
