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Varroa and DWV - it could happen to You!


After reading of your dwv and varroa incident, do you think there is any wisdom in treating swarms or nucs with oxalic acid/glycerin before introducing into your bee yard? Any negatives to consider?


Big can of worms here! :smile:

Many beekeepers have very strong opinions about this kind of thing. Some package suppliers do actually spray the bees with OA syrup before delivering them. Some beekeepers want their bees to be completely untreated, letting natural selection try to select bee genes for varroa tolerance.

I prefer to treat only when necessary. If we start treating unnecessarily, there is a risk of resistance developing to the treatment, as it has with overuse of antibiotics in humans. So when I get a new colony, I inspect carefully for disease when I install it. I then observe it closely as the numbers build up. When I have a brood box full of bees, I do a sugar roll mite count and treat if the mite count is high. If I start to see DWV, I don’t do a count, because it wouldn’t change anything - I am definitely going to treat anyway. Rotating treatments is important too, so if I have used any form of Oxalic Acid for the last treatment, I will choose something different for the next treatment.

So to answer your question in brief, some people would say there is wisdom in doing that, but I don’t do it myself. I covered the negatives above. :blush:


Well now, a sugar roll will give you some indication and as a swarm is broodless it is the ideal time for an oxalic treatment. I wouldn’t put strips of any kind as one vape is all you will need. There is no need for a treatment of any length.
I would quarantine ANY unknown swarm for one brood cycle and never feed for three days so that the bees’ honey is used in drawing comb.
I’m in the treat anyway camp as far as swarms go. Oxalic acid causes physical damage to the mites and resistance is unlikely.

That is all very well as long as you are actively involved in breeding yourself when you can be ruthless about culling non-surviving stock. You have to remember that VSH/tolerant bees are a tool not a treatment and so far the heritability of those characteristics are very narrow, tolerant bees have to be mated to tolerant bees not out-mated to Joe Bloggs’ bees in the apiary half a mile away.


Just curious if anyone is aware of, or has, any research/information on the evolution of pests & diseases & their relationships, associated with honey bees? Have Varroa, for example, evolved along side honey bees, how long have they been associated etc. Having evolved over a 100 million years, I wonder whether bees are capable of evolving to cope with the main pests & diseases they are presently dealing with & what they have had to deal over through out their evolution?


Not an expert, but have read a lot & consider myself a naturalist. It’s my understanding that honey bees are and will continue to be easy targets for varroa mites, only having come in contact with them starting in the 1980s so never having evolved alongside them in order to develop any sort of resistance - which of course would have had to happen over millennia. They’ll either be overcome & rendered extinct by the mites/diseases they carry, or maybe evolve some millennia from now :slightly_frowning_face:

Wow, I just looked at the list of invasive species on Wikipedia because I couldn’t recall the name of the fish species causing problems in our southern waterways (snakehead)…and saw under “other”, where varroa is listed, that earthworms are invasive here! Never knew.

Anyway, for what it’s worth, I’ve come to view treating bees for mites the way I view vaccines for people and pest treatment for pets. I’m going to inform myself & weigh risk/benefit among options - and I’m going to do it.


1980’s is very recent. Regarding evolution of coping mechanisms/strategies, I suppose I mean the next thousand/s of years? Why are they now susceptible to so many, tracheal mites, varroa, EFB, AFB etc? If we know what they have come up against previously too, perhaps it gives clues as to the way forwards? Not for treating of my own bees, simply curiosity…

I saw those snakehead fish on a program called River Monsters? They are incredible animals, & tenacious! It is hard to believe that earthworms could be invasive species? Not the most threatening of visual images :smile:

I have found this & couple of others so far…


Lol, no - though I found some huge worms in my garden yesterday, like small snakes :stuck_out_tongue_closed_eyes:

Well we only have our own species to blame, having “imported & exported” anything & everything since taking our first hike out of Africa!

And don’t get me started on pesticides…


We are to blame, no doubt. It’s like having a block of chocolate in the cupboard & taking a little bit, but you’ll save the rest for later. Then you take a bit more & a bit more till you think, there’s only half a block left I may as well just eat it all now, no point in saving it, it’s nearly all gone anyway.


If I recall correctly, Varroa destructor originally evolved with Apis cerana. It didn’t get into European honey bees until around the 1960s. The real problem emerged when it combined with various viruses, such as DWV. DWV had been around for years and didn’t really cause problems very often until V. destructor came along. Honey bees can tolerate DWV pretty well in the absence of varroa, but once they combine, it is hard for them to deal with the double hit.

I am afraid I don’t recall the references I read for this information (I read a lot! :blush:), but there is some information on Varroa destructor here:


Adaptation by natural selection requires the ability to produce lots of offspring.
Bees do not do this. Whereas vast numbers of female worker bees are produced they are sterile and cannot reproduce their genes.
Honeybees pass on their genes via their drones and it is only in a new queen that a new phenotype can be expressed and there are relatively very few new queens.
The honey bee has not changed to any degree of significance over millennia and this is probably why.

Fish, on the other hand are ideal candidates for Darwinian change

That isn’t to say that we as bee breeders cannot make a change


Quite right
A healthy bee carries low levels of several different DWV variants which are passed from bee to bee via feeding/trophylaxis
Varroa inoculation by injection of DWV changes the dynamics of the virus somehow…leading to the dominance of one or two of the normal variants which then reproduce to high levels giving you a sick bee


Perhaps I should re frame my question? I find it interesting that many of the pests & diseases presently affecting honeybees have emerged fairly recently to be very broad last 50 years or so (I’m not being exact here). Why, considering how long honeybees have been in existence for, are they coming to the fore now? What is it about honey bees in this past century which has made them susceptible to a growing number of parasitic organisms?

Over the 100 million years or so that bees have been evolving, have there been similar parasitic organisms? I’m not suggesting that we would see any evidence of evolutionary adaptations in bees within our lifetime. I don’t think Darwinian change is defined by a specific time frame of evolution. We have over 1500 different species of native bees in Australia. I think there around 4000 in the USA. Many of them have very specific ecological requirements & physical adaptations.Their diversity in form & habitat suggest that they are capable of evolutionary adaptation in response to environmental requirements. Has this included predators, parasites, etc.?
My understanding is that AFB & the like are Bee specific, most parasites evolve so as not to wipe out the host as they are dependent on them for their own survival. Which in turn implies some sort of co evolution.
There is some evidence that Apis cerana have developed some resistance to Varroa jacobsoni, but not clear whether this is true of the other 3 types of Varroa.


My best guess would be that is has something to do with the exponentially growing force of human influence, if we’re talking about the past 50 or so years.


I think what we have seen in recent times does not reflect any evolutionary ability, or lack of, but simply the increased introduction of foreign species to environments by man, accidentally or otherwise.

Evolution occurs over thousands and millions of years and has resulted in a balance of species within an ecosystem.

Obviously when major events happen, such as the ice age, many species die out and others survive and adapt over thousands of generations. Darwin himself came up with his theory by looking at isolated islands of the Galapagos and studying how animals had evolved differently due to the different selective pressures on the environment. You only need to look at Australia to see how amazing strange creatures can evolve on an isolated land.

And then humans mess with it! Like the man who introduced 10 rabbits to Australia so he could hunt them and within 2 years caused an unstoppable plague. Or the genius that released cane toads to deal with a beetle damaging crops, which have become an unstoppable plague, or the people who released foxes, or who accidentally brought in Portuguese millipedes, or the accidental release of Asian honey bees (with varoa) in a land with European bees. These things are such rapid events that the bees may not be able to adapt quickly enough to the insult and be made extinct… or they might evolve and survive :slight_smile:

rant over :slight_smile:


I imagine the increased movement of bee colonies, intentional & unintentional, would explain the spread of contagion. However that doesn’t explain how/why the origin of the parasitic organisms. Bee genetics weaker? Just find it all a bit fascinating & have lots research to do when I have time. One of the things that started me thinking about it is a mentor who is doing Doctorate re Varroa & Australian incursion/affect.


Good on you for seeking more facts! So far everything I’ve read ends up pretty depressing & basically points to pollution, plastics & pesticides disrupting more well-established & harmoniously balanced natural processes than I can stand thinking about. Bees are just one example. Sorry to sound so gloomy. But the truth will set us free :sweat_smile:

Earth Day is April 22nd and there will be a March for Science in Washington DC and many other cities :rainbow::evergreen_tree::tulip::sun_with_face::earth_americas::sunflower::butterfly::honeybee::turtle::whale2:


I find it incredibly frustrating & depressing too. We are in an age where we have so much information & the ability to act on that information, there can be no excuse of ‘didn’t know’ anymore. Yet our Prime Minister has just signed a deal with Adani Mines, who are acknowledged as causing some of the worst environmental disasters, which will have disastrous impacts on the already dead/dying Great Barrier Reef. In Tasmania they are logging some of the oldest forests we have, not hundreds of years old, thousands. It frightens me.


We definitely need more beekeepers in government!!!


We need more people too , to voice concern & make real change however small it might seem, in their own community.
I was listening to the radio a few weeks ago & person was talking about having successfully stopped their local council & 2 neighbouring councils from spraying pesticides to control weeds in public spaces. He was saying he became fed up with being angry all the time about what was happening in his local community. He decided that he was going to try & tackle the problem differently. He would come from a positive place. Instead of pointing the finger & saying this is bad, he found all the benefits for multiple aspects of the community, for changing the way they dealt with that particular issue. He found that by being positive he reached more people & a broader demographic. It was really lovely to hear of a successful community campaign.


Unnatural speed of exposure to a wider range of pests, caused by pesky humans mixing and moving bees around faster than they would migrate in nature.