What constitutes a "heavy" varroa load?

[The Riviera Kid]

I have been using the autumn evenings to read up about varroa. What constitutes a "heavy" varroa load - i.e. a badly infested colony?

I took out the boards from under the varroa mesh floor before and after treatment and counted the corpses... but I have no idea whether the figures are high or low as I don't know what is the expected benchmark figure for a hive with typical infestation.

What sort of natural drop should there be for a National hive over a period of x days? and what sort of body count should there be after apiguard?

 

[itma]

DEFRA/FERA suggest a *natural* average daily death rate of more than about 10/day should trigger strong treatment ("effective control").

Take a look at fig 50 (hidden away on page 31) of the 'Managing Varroa" booklet ...
download the pdf https://secure.fera.defra.gov.uk/beebase/downloadDocument.cfm?id=16


ADDED - since you are after natural death rate, no need a sticky board.
For the average rate, measure it over say 3 days, to get a good average and a countable (not too many) target (30).

During treatment, you might be hoping to get rid of 1,000 mites or so ...

 

[mazzamazda]

1000 mites!!!!!!!!

I've never had any more than 100 mites during weeks of thymol or oxalic acid treatments.

 

[itma]

1,000 mites has been quoted as a problematic level.
If you have a problem, you could have that sort of number to get rid of.

mazzamazda, it sounds like you might not have studied the text on page 9 and the graphs on pages 10 and 11 of the FERA Varroa booklet.
Its the official UK orthodoxy, so its as well to understand it.
Its a free download, so no excuses!


Ideally, everyone would like to be keeping the level much lower, but there's no accounting for what varroa-weakened collapsing colony your lot might decide to rob.

 

[Skyhook]

Or go the beebase calculator- that will give you an indication of how many mites you have in the hive, and how much of a problem that is.

https://secure.fera.defra.gov.uk/beebase/public/BeeDiseases/varroaCalculator.cfm

 

[mazzamazda]

Itma,

Of course I have, if I took the booklet on every word I'd never keep bees, a friend of mine destroyed a nuc as he thought he had afb, I'm not sure but it sounded like chalk brood.

I'd be seriously worried with a mite drop of 4-5000

 

[For want of a better word]

ADDED - since you are after natural death rate, no need a sticky board.
For the average rate, measure it over say 3 days, to get a good average and a countable (not too many) target (30).

During treatment, you might be hoping to get rid of 1,000 mites or so ...

Is that 1000 mites killed during a month of treatment with API.... as opposed to 270 natural count for same period ?
Most I have seen from an infested swarm was 309 dropped in one day ( on a sticky board) but rapidly reducing to < 10 per day within a week. ( Using APIGUARD)

Put the boards in occasionally to determine mite level and often get zero... but I bet the little beggars are there!

At least you are worrying about it !

 

[itma]

DEFRA/FERA have concluded that a hive population of 1000 mites is a serious problem.
Though they do point out that some other countries put the threshold higher, at 4-5000 mites.
1000 mites can turn into 5000 in 6 to 8 weeks.


But the DEFRA/FERA 1000 mites is indicated by their ~10/day natural death rate.
So, if The Riviera Kid is getting 10/day before treatment, he should be expecting to see something around 1000 dropping during treatment ... (but the error bars are still quite big for 3 days measurement).

 

[Finman]

DEFRA/FERA have concluded that a hive population of 1000 mites is a serious problem.
Though they do point out that some other countries put the threshold higher, at 4-5000 mites.
1000 mites can turn into 5000 in 6 to 8 weeks.

t).

every country has the same values in varroa. I have not seen why it is different. European Union Varroa Group has the basic work. Intermediate results has been used and it makes variation on recent information. Defra has followed European Union Group work all the time and it has informed UK WELL. Opposite powers has succeeded to make things from here to there. Famous inspectors have spoken for 15 y old methods. Some old farts I suppose or nature besser wissers.

Very few country has own varroa research. Best countries has been in EU GROUP. Missunderstanding has produced different figures to some countries like in Ireland.
Local society guys modify values, but they have no researches on their background. I have seen those guys in this forum more than enough.

**********


The point is that varroa douple itself in one month or in 4 weeks.

If you have in August 1000 mites, next you will have 2000, 4000 and then your winter bee brood are caput.

The beginning starts from 10 mites after winter

feb 10 .......30
march 20.......60
april 40...........120
may 80 ............250
june 160 .........500
july 320 ...........1000
aug 640 ..........2000
sept 1300 ........4000
oct 2600
nov 5000

"we must keep under 1000 mites". That guy who wrote so, do not understand the varroa.

We must hit the mites near zero that they do not make harm before next autumn.


If the chemical kills 96% of mites, out of 1000 it is 40 mites. Repeated handling -96% again and it is 40 x 4% = 1-2 mites.

When bees and drones fly, they move mites to another hives. No hive stays clean.

And don't trust that if you have on district 1000 hives it is your hive which resists the mites!

.

More information look from google "nanetti varroa control". Italian professor Nanetti is a man who you can trust on.

Now researches has concentrated their energy to COLOSS - PROJECT. It means that countries research widely the wellfare of honey bee.

..... And media will make their hype news. Mankind is still dying even if 7 billion value has just achieved.
10 years ago it was 6 billion.

.

 

[oliver90owner]

Ideally, everyone would like to be keeping the level much lower,

and

1,000 mites has been quoted as a problematic level.

Ideals and problematic don't go down too well with me.

The one thousand DEFRA figure is simply a threshold value for action. They are neither saying it is a problem or it is too high. Reading and understanding the text is important so that apathy or panic are avoided. Simple common sense actions are necessary.

The DEFRA information tends to say that if less than about a thousand mites in a strong colony, the bees can cope quite easily and little damage will result in the normal seasonal running of the hive.

Other places than the UK have different loading thresholds - and 3-4 000 mites does not cause undue concern, perhaps in the USA.

Threshold means the time to take action. Finmans figures demonstrate what is likely to happen if that action is not taken.

Ideally we would not have the varroa mite, but ideals are rarely achievable. There is too much emphasis on killing the last of the mites in a colony. That is unachievable as a sensible economic option. The simple way to achieve that is to kill all the bees as well!!

What should be emphasised is the need for adequate monitoring and timely intervention as required. Some say use oxalic in the winter and forget the mite until autumn. Poppycock - OK if you are experienced enough, but if the exceptions happen to include your only colony which then goes on to collapse (and spreads disease and pests to other local colonies), it is not very clever advice to give or follow. Neither good for the beekeeper nor any local beekeepers.

I say read and understand the DEFRA publication. Just having read it is not a waste of time but not understanding what has been written is a waste of a hugely useful resource.

RAB

 

[The Riviera Kid]

Thank you for all the input. I have read the "Managing Varroa" booklet but, as any novice knows, books are never a perfect substitute for a very experienced pair of eyes looking in to the hive with you.

I was a bit surprised by the body count post Apiguard. I do all the standard techniques for varroa control and periodically and there were no signs of long-term problematic infestation (e.g. deformed wings). The bees seem healthy and happy enough and have got plenty of stores for winter but I suppose as we go into the "quiet" time of year for beekeeping, I have this nagging doubt at the back of my mind that I have overlooked something that a more experienced keeper would have seen and I'll open the hives up next year and find loads of dead bees

 

[drstitson]

"I took out the boards from under the varroa mesh floor before and after treatment and counted the corpses"

can you clarify - were you briefly monitoring natural drop before treatment OR have you been keeping the trays in all the time?

 

[The Riviera Kid]

"I took out the boards from under the varroa mesh floor before and after treatment and counted the corpses"

can you clarify - were you briefly monitoring natural drop before treatment OR have you been keeping the trays in all the time?

To clarirfy, no, I don't leave the boards in all the time. I put them in briefly for a few days when monitoring natural drop and then again when treating with Apiguard in accordance with the instructions and to compare the drop to the pre-treatment rate over the same quantity of days. I tend to leave the board in place through the worst of the winter too.

 

[itma]

...
The one thousand DEFRA figure is simply a threshold value for action. They are neither saying it is a problem or it is too high. Reading and understanding the text is important ...

Rather than dispute the precision of a précis, instead let's just quote the actual words from page 9 of the DEFRA/FERA pamphlet:

There is no clear harmful threshold beyond which a mite population suddenly causes harm. A mite population that causes no obvious damage to one colony may prove very damaging to another. ...

However, in the UK researchers agree that it is a wise aim to keep the varroa population below about 1000 mites; above this level the risk of damage from the mites, associated pathogens and the effect of feeding on the bees can quickly become very significant. ...

 

[Finman]

.

"However, in the UK researchers agree that it is a wise aim to keep the varroa population below about 1000 mites; above this level the risk of damage from the mites,"

I just wrote that this opinion is false.

Do you have in UK any honeybee researhers? Not at least in varroa.

Show me the researches...

To keep mites under 1000 per hive. That is nonsense.

.

1000 mites is a limit after which colony will be in danger.

But before that honey yield starts to deminish.

Manitoba University:
Spring infestation levels of varroa on adult bees at average rates as low as 2% (2 mites per 100 bees) reduce honey production by 40 to 50%.


.

 

[Skyhook]

However, in the UK researchers agree that it is a wise aim to keep the varroa population below about 1000 mites; above this level the risk of damage from the mites, associated pathogens and the effect of feeding on the bees can quickly become very significant. ...

1000 mites is a limit after which colony will be in danger.

Sounds to me as though you agree!

 

[itma]

.

"However, in the UK researchers agree that it is a wise aim to keep the varroa population below about 1000 mites; above this level the risk of damage from the mites, associated pathogens and the effect of feeding on the bees can quickly become very significant. ..."

I just wrote that this opinion is false.

Do you have in UK any honeybee researhers? Not at least in varroa.

Show me the researches...

Finman, on this its you against the UK Government's Civil Service!
Its their official advice, and I'm happy to go along with their indication of the level of natural mite deaths that indicate that one should very soon be applying some form of effective varroa control.


Contact details are given at the start of their "Managing Varroa" document (linked near the start of this thread).
I'm sure they'd be happy to explain to you exactly what their advice is based on.

 

[Finman]

'm sure they'd be happy to explain to you exactly what their advice is based on.

I think that I have explainer to British beekeepers varroa managing 5 years. I have learned nothing from UK varroa advices. UK has travelled in late train, as we use to say.

Somehow an English professional stayed away from EU varroa group. At the beginning his name was there.

"U Project FAIR CT97-3686
This project lasted from 1998 until 1999. The main objectives of this Working Group were to co-ordinate research efforts in Europe on integrated Varroa control and to disseminate information to the beekeeping community on how populations of the bee parasite, Varroa destructor, can be kept below the damage threshold by alternative strategies. "

 

[RoofTops]

The NBU Varroa booklet is well out of date. I can't see any bee inspector these days saying anything other than beekeepers should keep varroa levels as low as possible by appropriate treatment at the recommended times of the year - irrespective of what the varroa count might be - because it can be a very unreliable guide to the number of mites present.

 

[TOBY-3652]

1000 mites??????? try nearly 9000 one of my hives dropped this no in a month