It has been discussed where to take the bees when making the test for infestation level of Varroa mites with the Bee Shaker. From a brood frame or just near the brood. The first week of May, I did a test with the Bee Shaker of a number of bee colonies. After that I inserted sticky boards to collect the natural downfall. This happened to coincide so that two colonies tested with the Bee Shaker also got sticky boards. The sample of bees for the Bee Shaker were taken from the middle of a the super just above the queen excluder.
A good compromise place to take the beesample from to the Bee Shaker is in the middle of the first super above the queen excluder. You don’t have to look for the queen. Not close to the entrance where the number of mites are fewer than average. And not far awav from the brood, when there are many honey supers. The number seems to vary more there.
Those colonies tested were choosen as I had found them to be potential breeders. The two colonies mentioned both had one (1) mite in the Bee Shaker out of about 350 bees, ie about 0.3% infestation level. Three weeks of natural downfall thereafter gave 7 mites from one and 8 from the other. The sticky boards covered almost the entire bottom. Let’s say I missed seeing two mites. If so it was thus about 0.5 mites per day.
Multiplying this figure with 120 I have heard gives a figure for the total number of mites in the colony. 0.5 x 120 = 60 mites in total then. The number of bees in the colonies were at least 30 000. But let’s say it was 30 000. Then 60/30000 would maybe give an infestation rate = 0.2%. But now I’ve seen reports that one should multiply by 30 (20-40). Then it will be completely different figures (in “favor” of the Bee Shaker). Collecting natural downfall should be done during the normal brood period, not in the very beginning or the very end of the brood season. In the case of the natural downfall of varroa mites, mites will also come from mites emerging from brood cells that have hatched during these three weeks. The natural downfall should therefore have given more mites compared with the Bee Shaker if these methods should have given corresponding figures. Therefore, the conclusion should be that the Bee Shaker revealed a greater proportion of the total number of mites in the hives than the natural downfall did.
The Bee Shaker could therefore be trusted to be an enough reliable tool to show infestation levels of Varroa mites, when samples are taken close to the brood, but not from brood frames. http://www.elgon.es/diary/?p=914
Following your early posts from this blog I found this:
http://www.elgon.es/diary/?m=201401
which made me change my attitude concerning your recent explanations about varroa infestation and the possible solutions.
Now I understand your management much better.
I never thought there is so much drifting but now I know.
Means: hard to see how much each hive is infested. It could change every day!
Now: how to select?
Use colonies thriving in spite of mites, maybe. No sickness observed in spite of mites could be the solution….
Using the hives with less mites because they do the VSH or mite biting….
Use the bee shaker to realize what`s the score while observing the brood pattern…..
Still, I´m very much confused.
There is so much to learn.
Sibylle
How to select? Focus on the most susceptible bees, unhealthy bees, bad bees, etc and get rid of those. Multiply the others.
You use the methods you find most likely work at the moment for you.
Bee shaker showing low infestation level is good. Cleaning out drone pupae while worker brood pattern is tight and nice without holes is good. No wingless bees is good. Strong colonies together with this is good. Survivor colonies giving a reasonable crop are good, etc.
Sounds very plausible that the bee shaker ist agood option to count mite numbers. However, the natural downfall number you have counted is very close, if you multiply with 120 to the number of the bee shaker. So it seems that this is not too false, if you rely on them (and if you don’t want to kill bees…). Of course a bigger statistic would help to confirm that, but first of all it sounds very close.
Yes, if you multiply with 120 the number is quite close. BUT those mites included in the natural downfall count are mites that have come out of hatched brood cells during the period of collecting the natural downfall. So the actual number fallen per day of only phoretic mites dying during a day is quite less, if that matters. Than another question. Is the number 120 correct? I’ve seen other figures that should be used to multiply with, for example 20-40. And the figure choosen are only valid during the period when the brood is of “normal” amount.
And then we have the possibility that the number of mites on the bees today are smaller in comparison to those of the total number that is multiplying or trying to, inside brood cells. All this means that it is very difficult to have any idea of how to compare natural downfall with an alcohol wash test.
Both methods are useful to get a hint of the situation concerning the mite population in the bee colony. the values you get you have to compare to earlier values done the same way and to other observations of the hives with different values.
Concerning killing bees, you are “killing” bees whatever you do, in different ways. Not doing anything you “kill” bees as many dies of different causes related mites and viruses. During the peak of the season 1-3000 bees are hatching, hundreds of bees are not succeeding in coming back to their hive but die in the field with their boots on with worn out wings or eaten by birds or wasps. An alcohol wash has an aim of rescuing many more bees. Well, it’s an interesting discussion too.
Valid arguments indeed,
my personnal aim is to find an additional measure regarding the infestation level to judge about the resistance behaviour of a hive. Earlier I concentrated on the number of wingless (DWV bees)/hive, which tells me when to remove the capped brood. But now after leaving the period of nuc splitting (as an effective method to keep mite number low), I want to know which are my breeders or my candiates to be queen shifted for bigger hives
Of course you keep notices and learn how to judge on the hive performance, e.g. hygienic behaviour of brood or drone brood. That tells you if the hive react, how fast he react and if he can control the situation. At the moment I’m very much interested in infestation level or tolerance level of a hive, when it start to react. It tells you whether a hive starts very early to detect mites or late.
Of course some hives learn via crisis and become better, but you have to commit to a certain value, when you will react.
I start to work with natural downfalls and the future will demonstrate whether this is a good idea or not.
Scientifically it would be a good idea to combine this numbers with alc wash and counting mite numbers by VSH test. But you know this is time consuming…
Yes, and when mite numbers get low, all methods get even more difficult. But then it doesn’t matter that very much either.:)