varoa treatment

[beeno]

Hi all and especially mbc,
Did a sugar dusting of one colony the other day, I will never forget the covered bees with their white eyes. Anyway, seem to recall that this was supposed to give a more accurate measure of how many varroa you have in the hive as compared to natural mite drop. Well, I got 15 mites in 24 hours and 17 in 48 hrs. I am not sure what I can infer from this result, if anything. I would be interested in how other beeks would interpret this level of mite drop from sugar dusting.

 

[pargyle]

Hi all and especially mbc,
Did a sugar dusting of one colony the other day, I will never forget the covered bees with their white eyes. Anyway, seem to recall that this was supposed to give a more accurate measure of how many varroa you have in the hive as compared to natural mite drop. Well, I got 15 mites in 24 hours and 17 in 48 hrs. I am not sure what I can infer from this result, if anything. I would be interested in how other beeks would interpret this level of mite drop from sugar dusting.

I don't think that will give you any better indication just by dusting ..

A sugar roll however will - you take about 200 bees from the brood area (these being the ones most likely to have mites on them) put them in a a jar with a couple of spoonfulls of icing sugar .. the jar needs a mesh lid (I use a Kilner jar with the removable metal section replaced with varroa mesh) and shake the bees up in the icing sugar, gently, then tip the jar over and the dislodged mites fall out through the mesh. Pisses the bees off a bit but doesn't kill them. Gives you a good idea of the infestation level ... even better with alcohol as you can count the actual number of bees and compare this to the mite number - but you have to get over killing some bees ...

 

[clv101]

This guy reckons most of the action (some 80% of the mites that are going to drop) takes places in the first hour after dusting:
http://scientificbeekeeping.com/pow...weet-and-safe-but-does-it-really-work-part-2/
He goes on to say the 24hr drop after dusting has a good correlation between the alcohol wash with even 10 minute drop rate being useful.

 

[charlievictorbravo]

This guy reckons most of the action (some 80% of the mites that are going to drop) takes places in the first hour after dusting:
http://scientificbeekeeping.com/pow...weet-and-safe-but-does-it-really-work-part-2/
He goes on to say the 24hr drop after dusting has a good correlation between the alcohol wash with even 10 minute drop rate being useful.

That's an interesting link - thanks for posting it. I was kind of hoping he might be able to give some indication of what percentage of the phoretic mites the sugar dusting knocked down. He was comparing 24 hour sugar drop with alcohol wash and said there was good correlation between the two for monitoring purposes but that implies that the sugar gets as many mites to drop as the alcohol wash. Does this mean it could therefore be used as an effective treatment - or am I missing something?

Even if you only knock down 50% of the phoretic mites, you will half the mite population in a month if you dusted every week - might not be easy if you've got 100 hives but for say 5 hives or less it's easily do-able.

Anybody know what the efficacy of sugar dusting is on phoretic mites?

CVB

 

[masterBK]

Ellis, M (2000). Using powdered sugar to detect varroa. Beekeeping and Honey Bees Newsletter, University of Nebraska(2): 1-3.

This paper the basis for the advice on page 35 in
CONTROL OF VARROA : A Guide for New Zealand Beekeeper
can be downloaded from
http://www.biosecurity.govt.nz/files/pests/varroa/control-of-varroa-guide.pdf

Sugar shake 70% of mites extracted from sample using brief shake with icing sugar but 79.8% if bees shaken three times or shaken until no more mites fall out.

This is less effectivethan using soapy water or alcohol extraction (80 -90%) (see page 34) but at least the bees survive the icing sugar.

This New Zealand publication well worth a read for information about all aspects of Varroa detection and control

 

[Hivemaker.]

..The efficacy of dusting honey bee colonies with powdered sugar to reduce varroa mite populations.

Within the limits of our study and at the application rates used, we did not find that dusting colonies with powdered sugar afforded significant varroa control.

http://www.ibra.org.uk/articles/20090217_5

 

[itma]

...
Even if you only knock down 50% of the phoretic mites, you will half the mite population in a month if you dusted every week ...

Can you explain that calculation, please?



If the hive is broodless (and thus there is nowhere for the mites to shelter and reproduce) then sugar dusting will indeed reduce the mite population.

But if there are plenty sealed bee brood cells, and especially if there is drone brood, I have become convinced that a weekly sugar knockdown is sadly unlikely to do more than slightly slow the rate of varroa increase - because the phoretic mite population is only a small proportion of the total, and the ruddy mites breed so fast.

 

[Finman]

.
80% out of mites are under cappings, when it is brooding period.

Drones pupa stage is longer, and it produces more adult mites.

 

[clv101]

I can't see the Ellis paper, did they explain how they came to use 120g every two weeks? There's a quick follow up study here concluding sugar dusting isn't much use: "Powdered sugar is thus, at best, another “weak” IPM component that may contribute toward varroa management when used in conjunction with other components." but is "most efficacious when it can be applied early in the season and exploit a winter brood-free period."
http://www.ent.uga.edu/bees/documents/RevisitingPowderedSugar-JAR51414.pdf

Interesting how it isn't much use in the field over a season, but is effective during the shake test and in part one of Randy Oliver's write up he reported "34% of all phoretic mites dropped in the first hour" following dusting, with 1 cup (125g) per box: http://scientificbeekeeping.com/pow...weet-and-safe-but-does-it-really-work-part-1/

What can we conclude? Dusting can give an indication of infestation based on the 1 hr and/or 24hr drop rate and the shake test works. But can't be used a season long control treatment. What about shortly after performing a shook swarm? Knocking off a significant proportion of the phoretic mites would be useful then.

 

[BeeJayBee]

Even if you only knock down 50% of the phoretic mites, you will half the mite population in a month if you dusted every week -

That would assume there is no increase in the mite population between dusting. At best, sugar dusting will decrease the phoretic mites, but it cannot do anything to those that are in with the larvae.

Back to Randy Oliver http://scientificbeekeeping.com/ipm-3-strategy-understanding-varroa-population-dynamics/

Unchecked, varroa can really multiply! A 12-fold increase is typical in a short season consisting of 128 days of brood rearing (Martin 1998). However, its population can increase 100- to 300-fold if broodrearing is continuous! (Martin and Kemp 1997).​

Use it with care because, according to our BI and the non-chemicals beekeepers in my association, trying to improve the kill rate by using more icing sugar can be damage open brood by dessication and if it rests too long on cappings it can sometimes absorb atmospheric moisture and set, stopping gas transfer so the larvae die.

 

[Tremyfro]

So there are not many ways of decreasing the varroa load during brood rearing. Icing sugar....decreases the number but not significantly.
MAQS....bees no likey and queen may go off laying.
Sublimation of OA....at 5 day intervals....any drawbacks?

 

[Hivemaker.]

MAQS....bees no likey and queen may go off laying.

Sometimes permanently, often damages brood and not effective enough.

Sublimation of OA....at 5 day intervals....any drawbacks?

None that i have come across with regards the bees, but can be expensive for some of the equipment and harmful to the beekeeper, or others, if used without proper protection.

 

[Finman]

.
And when you have 2 boxes brood and 4 boxes honey in the hive, it is not time to control varroa.

 

[Hivemaker.]

.
And when you have 2 boxes brood and 4 boxes honey in the hive, it is not time to control varroa.

Unless control is urgently needed, dead colonies will collect no more honey.

 

[Finman]

Unless control is urgently needed, dead colonies will collect no more honey.

If you do not believe preventive control, and you see urgent situation, treatment then is too late. That is the way it goes.

Like that "destroy brood frames" -method. It seems to be very popular among 2-hive consultants, and advisors do not even know what it means.

Bailey frame exchange is not better. How to get new combs annually..... Basics...

 

[Tremyfro]

In one of my hives....treated last year with MAQS....a few dead bees but otherwise OK. Some varroa drop down but not a huge amount. Treated with OA dribbled on in January. A higher drop down.
Some bees with DWV seen on landing board recently....they were baby bees so I guess they were thrown out of the hive.
After monitoring with varroa board and getting between 15-30+ varroa daily.
No supers yet.
Treated with Sublimated OA yesterday.
If we get a flow on during the 15 days of treatment....does it effect the honey? Could this honey be taken off and fed back during the winter if unsuitable for human use?

 

[Finman]

.
Normally one box hive is not able to get surplus honey. It uses all its honey and pollen to rear new bees. It takes one month to build up that hive is able to fill super boxes with honey

Your varroa load is bad, and it does not promise good.

Do you have drone brood gaps in the hive? Ay same time you see, how bad is mite contamination.
Gasifying OA weekly surely help the hive, but AS would be better.

Let the hive grow, and when it is about 3 boxes big, make an AS, and treat boath hive parts. Swarm part is easy to clean. Brood part you get cleaned during next weeks.

Read more about that method. I saw good advices in UK papers.


AS from one box size is not good, because nights are still cold. Swarm part would be too small to continue good build up.

Formic acid would be good stuff, but out temps are not enough.

 

[Finman]

.
Errrrf

 

[Finman]

.
And note. If your mite hive is near other hives, mites are easily drifted to other hives.

 

[Tremyfro]

First inspection was one week ago. The colony is on 14x12 frames with a national BB above. There are sealed honey frames I need to take out of the lower box but couldn't as we were expecting bad weather. The upper BB has 4 frames of brood too. There are many bees. The weather forecast for the coming week is better...so today the honey frames will be removed...this will give more space for the queen in the lower box. There are no supers on this hive. We have a field of OSR due to explode into flower in the next few days. So we go from nothing to everything within a week!