Phoretic vs non-phoretic varroa mites

[beeno]

Hi all,
Does anyone know what percentage of all the mites in a hive are phoretic as opposed to being in the brood? If you monitor over a period of 7 days and no brood has emerged you may vastly underestimate the amount of varroa in the hive. Thus 2.5/day with no cappings on the tray vs 23/day with emerging brood a week later on the same hive!

 

[oliver90owner]

Refer to the DEFRA publication. It is likely all there for the reader. Monitoring without consideration of the real-world situation will always likely lead to erroneous conclusions.

 

[jenkinsbrynmair]

would have thought the FERA ready reckoner would have taken all that into account, otherwise it's pointless using it. They're not that daft!

Monitoring over seven days and no brood has emerged - i would be more concerned with other things than faffing around with drop trays.
And if you start about queen being off lay and then coming back on - if that's the case it would be a ridiculous time to monitor as the phoretic mites would quickly be in the brood cells making up for lost time and regardless- it would not be an accurate figure.

 

[beeno]

I have read the Fera leaflet thanks. It was more of a heads up for newbies than something for the old timers to have a go at. Since I am a caring beek I did not want beeks to jump to erroneous conclusions. Maybe someone will come along in a minute, who knows the answer. Very happy with this colony thanks. They have paced themselves nicely and made lots of honey.

 

[REDWOOD]

80% of varroa are under rhe capped cells

Sent from my GT-S5570 using Tapatalk 2

 

[oliver90owner]

80% of varroa are under rhe capped cells

But not all of the time. That is where the 'thinking' has to be able to discern between instantaneous and real-world, well thought-out and sensible reasoning.

Thinking beekeepers can cope with that, the others just look for some definitive figure that they can cling to, unable to think for themselves or remotely understand that different situations might present non-standard situations.

 

[REDWOOD]

Quite right Rab, I should have been more specific.

 

[beeno]

Thank you Redwood, it would appear that is in the region of what the Varroa Calculator is working on at the moment. So, what's up with the twenty percenters, too slow to get into a brood cell?

 

[itma]

There is no true answer.
The percentage varies during the season, and will be dramatically skewed by any periods without new brood AND any treatment directed at phoretic mites (such as Apiguard and other thymol recipes, Oxalic, the upcoming Hopguard and even icing sugar).


In mid winter, when there should* be absolutely zero sealed brood, ALL the mites - 100% - must be phoretic, they have to be! Which is why that is the ideal time for an Oxalic treatment. (*Pedant risk! But such pedantry doesn't affect the central point here.)
On the other hand, in late spring, when there is likely to be a surfeit of available brood for relatively few varroa, the % phoretic is likely to be at a minimum.

The mites are phoretic simply to get transport to their next available on-the-point-of-capping brood cell. The quicker they come across one, the shorter time that they would spend as phoretic mites.


All "varroa calculators" would expect to be based on a 'normal' varroa population. However, if your varroa population has 'recently' been disturbed - for example by treatment or Q being off-lay (or even not present), then any such calculator is bound to give less accurate results than it would with a 'natural' varroa population.

 

[jenkinsbrynmair]

Thanks itma. Maybe we can now leave this thread as a pertty pointless exercise.

 

[beeno]

Thanks itma.
As a matter of interest I had 37% varroa in my drone brood in one colony. However, there was only one frame of drone brood in the there (first of the season in April). Shows the importance of drone brood checking... and culling if there is a problem - Integrated Pest Management.
Varroa is a very important subject matter this time of the year. Get it wrong now and your colonies can be dead by Christmas. If you are feeling too old and tired Jenkins it's ok to have a rest.

 

[jenkinsbrynmair]

Just tired of inane and pointless twittering.

 

[Finman]

Thanks itma.
As a matter of interest I had 37% varroa in my drone brood in one colony. However, there was only one frame of drone brood in the there (first of the season in April). Shows the importance of drone brood checking...

But mites are not only in those drone brood. Sounds bad that 37% and it tells that you have mites really much in the hive. It needs now treatment.

 

[beeno]

But mites are not only in those drone brood. Sounds bad that 37% and it tells that you have mites really much in the hive. It needs now treatment.

Hi Finman,
This was back in April. All is well and all my hives are being treated with homemade Thymol at the moment. Not much of a Phoretic drop, but 52 overnight on one hive which coincided with emerging brood.

 

[DanBee]

The accepted average (ITMA's comments accepted) is 30% phoretic / 70% reproductive. We do not often see winter broodless periods here.