It is well known that some colonies of bees have traits such as grooming or hygienic behaviour which make them better able to cope with Varroa. Pinpointing such colonies with the aim of selectively breeding from them can be a challenge. There are several different methods and they range from the meticulous to the downright ruthless.
Monitoring Mite Fall
This involves counting the daily mite-fall by examining a greased slide placed below the mesh floor. It can be done once a week or every few days and the total divided by the number of days since the last count.
The National Bee Unit has an online Varroa Calculator – feed your data into it and it will tell you when you next need to treat.
Bear in mind that the daily mite-fall varies wildly thoughout the season depending on: how strong the colony, how much brood, how much drone brood, have you split the colony, has it swarmed, is it queenless not to mention the whether the weather…
Apart from counting the mites here are some other things to look for…
Signs of Grooming
The dead mites can be closely examined with a magnifying glass. If mature mites – dark reddish brown in colour – are found with bite damage such as missing legs or damaged carapace you can conclude that some grooming is happening. Don’t leave too many days between your counts or you may find yourself looking at Varroa corpses damaged by the generalist invertebrate detritivores that inhabit the dark cornersof the hive floor.
If you divide the number of bitten mites by the total number of mites and multiply by 100 you’ll have an idea of the percentage of grooming activity in your colonies.
Signs of Hygienic Behaviour
Signs of hygienic behaviour to look for would be bits of dismantled pupae and immature Varroa (small pale coloured). Click here for Illustrations
An indicator of possible generalist hygienic behaviour is Chalkbrood, or rather a lack of it in the brood nest when it is present in other colonies in the apiary. Look for umpteen grey mummies on the floorboard and lack of it in the brood nest.
Measuring Hygienic Behaviour
It is possible to assess the level of hygienic behaviour in your bees by adding a frame of capped larvae which contains an area where all of the the pupae have been killed.
- You can either kill they by piercing them with a slender needle – sharp or crewel;
- Or if you prefer to live dangerously, get hold of some liquid nitrogen and use it to freeze-kill an area of pupae;
- Either way – mark the area and count the killed cells;
- Come back in 24 hours and count the number of cells the bees have broken into and removed the dead contents;
- Divide the total removed by the total killed and multiply by 100 to get your percentage hygienic behaviour.
A word of caution here – it is possible that the bees respond to different cues with these tests. Just because they are acutely aware when a pupa has been lanced or frozen doesn’t necessarily mean they would notice when a Varroa laid an egg in a sealed cell. It would give you an idea of general hygienic behaviour but not necessarily Varroa Sensitive Hygiene (VSH) which is different.
Again this is time consuming.
Icing Sugar Test
For most stand-alone beekeepers – the bottom line is how many Varroa are in the hives at the end of the active season after the honey has been removed and before the bees are treated.
If this can be determined, it is possible to make a decision about whether to treat or not to treat. A relatively simple test is the icing sugar test.
By the way, if you are going to do this – only test hives that have not been treated since the spring. Also – did you split them during the year because this could have a bearing on the count.
Here’s how it’s done anyway…
- A big plastic bucket suitable for shaking bees into;
- Plastic beaker with 300ml level marked;
- Perforated cap to fit or a bit of net curtain with holes smaller than bees but bigger than varroa and a rubber band;
- If you sign up to help NIHBS and NUI Galway find the Varroa Resistant Native Irish Bee you’ll get a free, custom made beaker like this one above. Details here: http://nihbs.org/wp-content/uploads/2013/09/Breeding-for-Varroa-Resistance-in-Ireland-Final.pdf
- Icing sugar;
- A tablespoon;
- A white plastic bucket with water innit.
- Find your queen and isolate her;
- If you can’t find her, take a frame from the centre of the brood nest and make sure she’s not on it;
- Shake the bees off the frame into the bucket;
- Scoop 300mls of bees into the plastic beaker and put the lid on;
- Shake in a tablespoon of icing sugar through lid;
- Tumble the bees around till so they are well coated;
- Leave them alone for 5 minutes;
- Tumble them around gently for a count of ten then;
- Get your white bucket with water innit;
- Invert your beaker over it and shake till no more Varroa fall out;
- Count the Varroa – they show up very well against the white bucket;
- Divide the number of Varroa by 3 then, if there is capped brood, multiply by 2 and that’s your percentage infestation. If there is no capped brood don’t multiply by 2, just divide by 3.
The people from Galway tell me this test, although indirect, is a very accurate measure of how many Varroa are in the actual hive.
Their advice regarding treatment is that if there are 2 or less mites per 300ml of bees you probably don’t need to treat but if there are 3 or more you should treat.
The Bond Method seems to have evolved in Germany. The name derives from the James Bond film Live and Let Die. Dr. John Kefuss is a scientist and commercial beekeeper who lives in France and who has decided for one reason or another that treating for Varroa is a fools game. He took a calculated plunge and stopped treating his bees. He had thought long and hard about it and was prepared for a 90% loss so was pleasantly surprised to lose only 60%.
That might seem catastrophic but since then he has bred from the survivors using ‘caveman genetics’ and is now back to full strength. However, he now no longer treats – AT ALL. He loses on average 15% per year but this is not out of line with his neighbours who do treat.
As somebody who lost 50% of her bees in the endless winter of 2012-13 I know a bit about losing lots of bees. 50% is catastrophic but I was back up to full strength again by the end of that year. You know yourself – bees really go for it when they can.
While it may seem very drastic to allow your bees to be decimated in this way it should be borne in mind that not only are the bees decimated but the most virulent strains of Varroa are decimated also. Virulent strains are failed parasites if left to their own devices because they take so much from the host, the host dies and the parasite dies with them. As long as we blanket-treat all our bees we are helping these strains to survive.
When you stop treating your bees, eventually you are left with the most capable bees and the least capable Varroa
But this could take years. Here’s a way of speeding it up.
Bond Accelerated Test (BAT)
This method was devised by John Kefuss. It is where the Bond selection method is speeded up by adding frames of infested brood to survivor colonies. The effect is to accelerate the selection process – killing out non-resistant strains of bees more quickly – 6 months rather than 3-4 years. You need a heart of stone for this stuff – but that’s science for you.
Soft Bond Method
This method is a variant of the above method for those who lack the nerve or the confidence or the sheer numbers of bees to try the hard versions. It involves selecting a portion of your stocks to experiment with and say to yourself ‘I could afford to lose this lot’ – accept it and carry on.
Here are John Kefuss’s Soft Bond Method Instructions for Big Beekeepers:
Procedure for the selection of up to 20 breeder queens from an apiary of 500 (!)
- From the initial group of 500 hives, select the 100 best producing colonies;
- On those, perform 24-hour hygienic tests;
- Select the most hygienic 40 for Varroa count;
- Spread this breeding material by rearing daughters and requeening in all bee yards to produce selected drones;
- Leave the best 20 of the selected hives without treatment – the Bond Test to produce breeder queens.
There now – gird up your loins.
Soft Bond Method for Small Beekeepers
For those of us with too many colonies to count mites and not enough to do a full Bond or BAT test here’s something we can do.
- Use the Icing sugar method above for as many of your colonies as is practical;
- Resolve to count and examine mite-fall in the best of these next year;
- Add all of this data into your Colony Assessments and Colony Appraisals and use all the data to select queens to breed daughter queens and colonies to raise drones;
- If you have the nerve – stop treating the best of them and see what happens;
- If you don’t have the nerve or the numbers of bees to play with, then at least get in touch with NIHBS and join the Ireland Varroa Monitoring Programme.
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