Sugar dusting

[Ginger19]

As a relative newbie still, I thought I would share my experience last week.
I have treated only with January Oxalic trickle in my 2-3 years, but came out at Spring minus 2 queens. So that is the end of Oxalic for me.

The last few months I have monitored natural mite drop and as it was so low I was thinking do I need to bother treating at all? So by way of assessment I decided to dust them with sugar. The results are pretty instant, 3 of my 4 hives dropped maybe 20 mites within 10 minutes. The other dropped 100's. So that hive is being treated with Apilife Var, and is on treatment 2 of 4, with good results.
This hive did not have a brood break, which seems to be key. The others were either a caught swarm or re-queened and would have had a period of time with no sealed brood.

With regards to icing sugar, I was concerned about the additives they put in (Maize starch or Anti-caking agent). So instead I used ordinary cane sugar but blitzed it in the food mixer for several minutes. Worked really well, especially when sieved over the hive.

I know some think it is a waste of time. Does anyone else sugar dust?

 

[Cussword]

I tried it a few times this year. I have just treated the same hive with Oxalic Acid by sublimation.

The mite drop terrified me! Forget Icing Sugar Dusting, as a treatment

 

[B+.]

3 of my 4 hives dropped maybe 20 mites within 10 minutes. The other dropped 100's. Does anyone else sugar dust?

You are definitely in the should treat category with that number of mites!

The time to do natural mite drop tests is in the early spring (before there is any significant amount of brood) because the mites will still be on the adult bees. Once the pollen starts coming in and they start brood rearing (i.e. Late March/Early April onwards - depending on when the willows flower in your area), the natural mite drop test becomes less reliable because mites will start moving into the sealed cells to reproduce.
If you are really interested in doing continuous assessment, you should probably use the pin-killed brood test or freeze-killed brood test. I would suggest that the pin killed brood is much easier. However, there are a few tricks that they don't tell you in any of the literature:
1. Age of the sealed brood is important.
The bees remove dead larvae and young pupa more readily than older bees. You should only perform this test on bees that have reached at least the pink-eye stage (mark a frame containing eggs/larvae and wait for the correct time or uncap a cell to find a patch the correct age).
2. The literature suggests that you leave the pierced brood for 8-12 hours before counting the cells cleaned out. It really needs to be closer to the 8 hours than 12 to differentiate between the most hygienic colonies.
By the time you get to July, you really need to start looking at 50g samples of adult bees taken from the super and, instead of doing sugar roll tests, do the soap wash test because there is just too much going on at that time of year (e.g. extracting). With the soap wash test, you can hold the bees in the freezer in marked containers until you have time to do the counting (although this probably defeats the point of doing continuous test because you won't get the result immediately). You can do the soap wash test every 3 weeks to make sure you cover the new mites coming out of worker cells.

 

[Hivemaker.]

you really need to start looking at 50g samples of adult bees taken from the super

How do the mite numbers of bees in supers compare to those taken from young bees on frames of open brood, as mites prefer young bees and like to be near the brood in which they breed.

 

[B+.]

How do the mite numbers of bees in supers compare to those taken from young bees on frames of open brood, as mites prefer young bees and like to be near the brood in which they breed.

I have a paper somewhere on this, but, ...the varroa female goes into the cell shortly before capping to reproduce. At other times, they will be on the adult. It is easier to collect mites from adult bees than to count them in the cell (protonymphs and deutonymphs are transparent/creamy coloured and quite hard to see without a microscope).
The infestation will be quite uniform so you are looking for an estimate, not an exact number as this has no meaning...it is changing all the time...just like the number of bees in a colony. Of course, as the season progresses and the queen stops laying, there will be no mites in the brood. They will all be on the adult bees.

 

[Hivemaker.]

I have a paper somewhere on this.

I would like to see that... if you can find it and put it on here, i am interested in the accuracy of the % of mite infection taken from bees on a frame of open brood, compared to say bees taken from a top super, that could be say...three/ six boxes up from the brood area.

 

[B+.]

I would like to see that... if you can find it and put it on here, i am interested in the accuracy of the % of mite infection taken from bees on a frame of open brood, compared to say bees taken from a top super, that could be say...three/ six boxes up from the brood area.

Its always going to be in a state of flux because bees will be emerging and transitioning through their different jobs before eventually becoming foragers. Thats why taking a 3 week sample allow you to plot the development over time.
I have a chart that I produce for each colony (see attached). It comes from one of the German bee institutes but you can get the idea: plot actual mite counts at 3 week intervals, produce a line of best fit and extrapolate into the future. The colours are like traffic lights: green is safe for now, amber is caution and red is imminent danger.

 

[Hivemaker.]

I know how to work out the % of mites from a test of bees taken from a frame of open brood, and this is how it is done by the scientists/researches that i have seen, i am wondering why they are going to the trouble of doing it this way, if you say that just shaking out a sample of bees from a top honey super is just as accurate, it that what you are saying?

 

[oliver90owner]

What exactly is an 'adult' bee? Is it defined in this report? To me the imago stage is the adult, whether it might be recently emerged or on foraging duties. The other stages in the life cycle are still bee stages, but as usual some would not recognise this as such. Some might even call the larval stage 'baby bees'.

 

[B+.]

I know how to work out the % of mites from a test of bees taken from a frame of open brood, and this is how it is done by the scientists/researches that i have seen, i am wondering why they are going to the trouble of doing it this way, if you say that just shaking out a sample of bees from a top honey super is just as accurate, it that what you are saying?

Why do you think the distribution of mites would be different in higher supers? Its the age of the bee that determines the job it does. The only thing that would change is the number of mites emerging as the number of bees emerging changes.

 

[Hivemaker.]

Why do you think the distribution of mites would be different in higher supers?

I am asking you, is the % of mites on young nurse bees on frames of open brood going to be the same as on the bees working in a top honey super.

This is one of the reasons i am asking you.

Select a comb of open brood with larvae which is close to being capped (this is the scenario most favored by the mites as they try to move in to a cell just before it is capped.

Can you find the paper that states what the % of difference is, if any.

 

[B+.]

I am asking you, is the % of mites on young nurse bees on frames of open brood going to be the same as on the bees working in a top honey super.

This is one of the reasons i am asking you.



Can you find the paper that states what the % of difference is, if any.

I've been out at an agm all evening but I'll get back to you when I have a proper answer.
My understanding is that the distribution of mites is uniform on adult bees, but, due to differences in the queens laying pattern, there may be a sort of stop-start effect on the release of new mites from emerging brood cells. I am not aware of any reason why mites in supers that are further up a stack should be any different to those immediately above the brood as this would mean they weren't uniformly distributed. I thought you were saying you had observed this, which is why I was trying to understand exactly what you were saying.
Mites do enter the cell shortly before it is sealed though (https://aristabeeresearch.org/varroa-resistance/) so their population growth would be governed by the amount of open brood. If the queen was prevented from laying for any reason, like a sudden influx of fresh nectar which temporarily blocks the brood nest, this could restrict the options available to the mother mite. The bees in the supers don't stay in the supers all the time though, they'll come down to receive more nectar and mites will transfer onto them.

 

[Hivemaker.]

My understanding is that the distribution of mites is uniform on adult bees,

So an accurate count of the % of varroa infestation could also be obtained by catching a sample of... say 300 bees returning to the entrance of the hive, just as accurate as taking a sample from young nurse bees feeding open brood...yes?

 

[Finman]

AsI have treated only with January Oxalic trickle in my 2-3 years, but came out at Spring minus 2 queens. So that is the end of Oxalic for me.

?

Oxalic trickling does not kill queens. It is sure, Reason is somewhere else.

You may give wrong dosage, but it must be quite much wrong.

 

[Finman]

I am asking you, is the % of mites on young nurse bees on frames of open brood going to be the same as on the bees working in a top honey super.

This is one of the reasons i am asking you.



Can you find the paper that states what the % of difference is, if any.

No paper is needed. 80% of mites are under cappings of brood cells.
It does not matter are yhe mites in Super on in lower boxes.

And mites double themselves in one month. When you have 10 mites in Marsh, you will have 1000 in September.

I do not calculate mites., I kill them.


.

 

[rook66]

So an accurate count of the % of varroa infestation could also be obtained by catching a sample of... say 300 bees returning to the entrance of the hive, just as accurate as taking a sample from young nurse bees feeding open brood...yes?

Not according to this paper by Zachary Huang. Go down to mite preferences.

http://www.extension.org/pages/65450/varroa-mite-reproductive-biology#.Vh3xNMtwZpU

 

[B+.]

So an accurate count of the % of varroa infestation could also be obtained by catching a sample of... say 300 bees returning to the entrance of the hive, just as accurate as taking a sample from young nurse bees feeding open brood...yes?

I wouldn't do it that way. I'm a bit picky about having consistent samples as you can introduce all sorts of errors that can invalidate the test altogether.
As I see it, there are two problems with taking the sample the way you suggested.
1. They may have shaken mites loose during flight.
2. They can be anything up to six weeks old.
By taking the sample from the super, you are taking a sample of consistent aged bees. 50g of bees (the recommendation is for > 30g) isn't a lot of bees to sample and there is no danger of including drones by taking them from the super.

 

[Hivemaker.]

Not according to this paper by Zachary Huang. Go down to mite preferences.

http://www.extension.org/pages/65450/varroa-mite-reproductive-biology#.Vh3xNMtwZpU

Not according to B+.

 

[B+.]

Not according to B+.

Rook66 - That article talked about a number of factors affecting mite reproduction, but nothing about distance from the brood area which is what HM was talking about.
I don't see anything in that article that contradicted anything I said.
For a consistent sample, I would still recommend taking it from the super for the reasons I stated above. The point about phoretic mites prefering nurse bees to foragers needs to be considered carefully. I certainly wouldn't recommend people to start taking samples from the brood nest because, I feel sure, someone will collect an indeterminate and inconsistent number of drones (and god forbid, even a queen!). It is much safer to recommend samples be taken from the super as those nurses will transition to become wax drawers/honey packers anyway. I accept that they may lose a few phoretic mites along the way (bees rub against each other in the hive and may dislodge some), but this will be stable.
I've just tried to provide a common sense recommendation that anyone can follow no matter whether they are an experienced beekeeper or a beginner. There is certainly a lot more invasive tests you can do, but, I don't think many people would do these.

 

[Thymallus]

It seems even the scientific literature is quite divided. From the paper that Rook66 kindly posted a link too....very interesting BTW.

Whether or not varroa mites can choose phoretic hosts was studied previously, using caged bees and petri dishes. Varroa mites preferred nurses when they were presented with a choice between foragers and nurses in a petri dish. Mites also transferred more often to young bees than to old bees, when they were confronted with freshly frozen young and old bees. This discrimination by varroa was later shown to be related to the repellent effect of geraniol, a component of the Nasonov pheromone, which is high in foragers. However, it was not clear whether mites show the same preference under a more realistic colony condition. One study showed nurses had a higher percentage of mites than newly emerged bees, but no difference was found between nurses and foragers. Another study found nurses were the most preferred but the experiment was conducted in one colony (i.e. not replicated). My laboratory studied mite distribution among one-day-olds, nurses (5-11 day old marked bees recovered from a colony) and foragers (unknown age but the average age of foraging bees should be higher than 21 days in a typical colony), and found a clear preference of nurses > day-old-bees > foragers (X. Xie, Z.Y. Huang and Z. Zeng, in preparation). Thus, mites do show the same preference for nurses, even in a colony setting.