Archives for posts with tag: Varroa mite

I decided to try a prophylactic mite treatment for my hive after doing the powdered sugar roll a couple weeks ago. You may recall that my test failed due to operator error and it appeared that I did not have any mites. However, among beekeepers in this part of southern California it is known that no mites is highly unlikely, so I was fairly certain that I have mites in my colony; I had simply failed to detect them. I spoke with my beekeeper friend who shared with me some pictures of mites on the bottom boards of her colonies. We even played a little “Where’s Waldo”-esque game of Find the Mite to help me develop a good search image. Equipped with this information, I carefully searched the bottom board a few days later and I found a couple of the little buggers. (Side note: my aging eyes are getting more problematic. I’ve found that even wearing my glasses, the mites are too small for me to be certain of them so now I take a picture of the area where there is something that resembles a mite and then zoom the picture in closer to confirm. Perhaps I’ve found a use after all for Marc’s odd real estate gift magnifying glass he handed me a few weeks ago.)

European honeybees (Apis mellifera) are not co-evolved with the Varroa mite so they have not developed adequate adaptations to this threat, which they have only been dealing with since sometime in the 1960s for the species, and since the 1980s in North America. Varroa mites were originally known in Asia where they parasitize Asian honeybees (Apis cerana), a different, albeit sister, species. I’ve been looking into the array of methods one can use to treat for these mites and the reasons for and against treatment. As a biologist, I tend to agree with some of the treatment-free beekeepers I’ve read. In this philosophy, mite infestations are generally viewed as a genetic issue best handled by re-queening from a treatment-free breeder. A queen bred from stock that has survived without the use of chemical treatments should have genes better adapted to combating and co-existing with the mite. This is why I opted to purchase my queen where I did, since they have queens that have been selected for what is known as VSH, Varroa selective hygiene. Increased mite resistance is also one of the advantages for keeping feral colonies with some Africanized genetics who seem better-adapted to handling Varroa.

A powdered sugar dusting is one non-chemical method that can be used to encourage bees to clean themselves, which results in mite removal. This method does nothing for the mites that are busily reproducing in the capped brood cells, so multiple treatments are needed in quick succession to have any hope at reducing mite numbers. On some sites I’ve read that store-bought powdered sugar, which contains corn starch, is hazardous for bees and it’s recommended to make your own by putting granulated sugar into a blender. Other sites have cited research that cornstarch-laced powdered sugar is not harmful to bees, but other anti-caking agents are. I had powdered sugar on hand, so that’s what I used. After checking the bottom board this morning, I counted five mites. I’ll check the board again the next two days so I can get an average daily mite drop, and I’ll sugar them again in a week. Aside from the mites, the colony appears healthy. They are chugging through their sugar syrup and there were plenty of bees, capped brood, and capped honey visible on the few frames I pulled out.

So I’ve mentioned doing a mite check for a while now and finally did my first one over the Thanksgiving weekend. It was an epic fail that might be better described as a series of what not to do. I had read about the method I had selected; I probably should have looked online for a YouTube demonstration of the technique prior to attempting it myself. Perhaps I will remember that the next time I attempt something. Knowing me, I will not.

Varroa destructor, Varroa mite, is a common parasite of the honeybee. I’m not going to post any pictures because I think they’re pretty icky looking. Wikipedia has a good close-up image though, if you’re curious. This particular mite is a vector of multiple viruses that are passed to infested honeybee colonies. Serious infestations can result in death of the colony unless beekeepers step in with a variety of tools to protect their bees. The mite is native to Asia and so European honeybees, the most common honeybee in North America, have not evolved with this parasite and do not have adequate defenses against it. Beekeepers breed queens from selected stock with genetics that are more resistant to the mite, mainly through increased cleaning behaviors that are more likely to remove the mites. Africanized colonies are also thought to be more resistant to this threat. From what I’ve read, the mite is found throughout the United States. There is a citizen science project, Mite-A-Thon, to track mite levels across North America, but it is dependent on voluntary participation so a high reported mite level could mean that mite levels in the area are higher than other areas, but it could also mean that there is a high level of participation in the area.

There are a few methods to determine the mite level in a colony: alcohol wash, sugar roll, and a sticky board. The sticky board is a passive method that requires a layer of some sticky substance on a board placed under the hive. After three days, one looks at the board and counts the number of mites. This is not the most accurate method to use because it depends on the mites falling off or being cleaned off the bees for them to then land on the sticky board to be counted. The other two methods count the mites actually found on the bees. The alcohol wash is likely the most accurate, but it also kills all the bees used in the sample since they are swirled in alcohol to remove the mites, and then the mites are counted in the alcohol. The sugar roll is a similar method where the bees survive since they are only swirled in powdered sugar and can survive this level of abuse. So that was my preferred choice. Both the alcohol and sugar methods require collection of a sample of approximately 300 bees from different frames in the hive. Ideally the sample is composed primarily of nurse bees from the brood combs as these are the youngest bees and most likely to have mites since the mites attach to baby bees in the brood cells and emerge with the newly hatched bees already attached to them. The video is a great demonstration of how not to collect bees.

Besides my troubles with collecting bees, I also missed a key step in the method. After coating them, I was supposed to let the bees sit for a couple minutes to give them time to heat up in response to the sugar, which then causes the mites to release from the bees. You’ll see in the video my other error.

So after all that, the answer is that I still do not know if I have a mite problem or not. It has been so cold lately that I haven’t felt like disturbing them again so I may wait until spring to try again. Plus, I need to find a finer mesh screen to use that keeps the bees safely inside. My hope is that I won’t have a large mite problem yet since the colony was so small to begin with and I started with a queen known to have more hygienic behavior who will pass that on to some of her offspring. This may be wishful thinking.

I’ll leave you with a photo of my favorite assistant doing what he does best: enjoying the sun. I love this guy more than words can ever begin to express. He’s snoozing next to me now as I type this, hogging the entire chaise lounge and leaving only a small section of the sofa for Marc and I to share.

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