Sudden huge mite drop!?

[Eyeman]

Well I'm glad I'm not the only one who has a colony that does not play by the rules.

I've been struggling to understand why, after 5 vapes, they're still dropping 30 a day.

Has anybody, including Erichalfbee and Beefriendly, come up with a plausible explanation for continued high drops when all the mites should in theory be dead.

Could be be something to do with the squat shape of hives such that the whirling cloud of Oxalic Acid vapour does not get right into the corners so a few varroa mites get away to reproduce in future cycles of bee brood? I don't know but there clearly is an explanation out there somewhere.

CVB

Not sure why your worrying about trying to knock down all the mites. All you need is to get the numbers down so that there isn't any impact on the winter bees.
Leave the 'kill the last mite' until you do the winter treatment when there isn't much brood around.

 

[charlievictorbravo]

Not sure why your worrying about trying to knock down all the mites. All you need is to get the numbers down so that there isn't any impact on the winter bees.
Leave the 'kill the last mite' until you do the winter treatment when there isn't much brood around.

You're right of course but Beefriendly has done 8 vapes and is still getting 100 per day - there has to be an explanation, when theoretically 4 vapes at 5 day intervals will get them all. I'm sure Beef wouldn't aim to kill every mite but he'd sure like to get the drop into single figures!

CVB

 

[Eyeman]

You're right of course but Beefriendly has done 8 vapes and is still getting 100 per day - there has to be an explanation, when theoretically 4 vapes at 5 day intervals will get them all. I'm sure Beef wouldn't aim to kill every mite but he'd sure like to get the drop into single figures!

CVB

My take on this is:
1. The newly emerged mite remains phoretic for an average of 5 days before she enters a cell. This 5 days is an average with some mites entering cells after only 1 day and others longer than 5 days.
2. We don't know how long a single vape of OA remains effective.
3.It could be that in BeeF 's colony the mites are only remaining phoretic for 1-2 days so limiting the opportunity for OA to be effective?
4. Treatment using a shorter interval may be more effective in this situation?

 

[Beefriendly]

Not sure what the answer is. Might be a limit to the amount of mites OA can kill with a single vape and if the numbers are beyond that.......
There is no way it is working at 97% efficiency....or I'm not vaping correctly. But Sublimox and double dose and it's definitely working as witnessed by 1000+ mites being killed at the start of the treatment. The good thing is all signs of DWV have now disappeared.
Not trying to kill every mite but single figures is the aim for most hives.
8th vape (with sublimox and double dose) o/n drop down to 32 mites this morning....nearly there. Or would you consider 32 mites as low enough? It will probably be around 60-70 by 48 hours.

 

[Erichalfbee]

My aberrant hive is at the end of the line of boxes. They are out all ours and weathers. They have more stores than they know what to do with. I'm sure they are robbing some colony out.

 

[madasafish]

I had a similar problem this time last year. Huge drops during Apiguard and still 100 +/day with OA following.

I used Apistan - never used it before - and it killed approx 500 mites and the final drop was minimal. Hive now OK.

Doing the same this year without the OA bit - on another hive.

I concluded OA on badly infected hives with brood does not work thoroughly so will not try it again.

 

[beeno]

My aberrant hive is at the end of the line of boxes. They are out all ours and weathers. They have more stores than they know what to do with. I'm sure they are robbing some colony out.

Yep, reinfestation through robbing is a possibility.

 

[Beefriendly]

My aberrant hive is at the end of the line of boxes.

Mine is 2/3rds along a line of 12. All the others have reasonable mite drops on treatment and 4 vapes each will probably do for them. But this one!

 

[charlievictorbravo]

My take on this is:
1. The newly emerged mite remains phoretic for an average of 5 days before she enters a cell. This 5 days is an average with some mites entering cells after only 1 day and others longer than 5 days.
2. We don't know how long a single vape of OA remains effective.
3.It could be that in BeeF 's colony the mites are only remaining phoretic for 1-2 days so limiting the opportunity for OA to be effective?
4. Treatment using a shorter interval may be more effective in this situation?

Where did you find that information? Zachary Huang here says "The phoretic stage lasts about 5-11 days when there is brood in the colony." so the 5 day figure appears to be a minimum, not an average. This paper says 4.5 to 11 days. The usual 4 treatments, 5 days apart should work but clearly, in some cases it doesn't. Maybe 5 treatments, 4 days apart will do it.

The robbing of an infected colony remains a possibility. My suggestion of mites in the extremities of the hive escaping the OA might be plausible with a heated pan-type vapouriser but Beef's Sublimox would produce so much vapour, under pressure that nothing, even in the corners, is likely to escape a coating of OA crystals.

I seem to remember reading some research a few months ago that counted mite drop after OA vapourising treatment and that suggested that OA was active in the hive for about 30 days, if memory serves. I recall seeing a graph of cumulative mite drop that tapered off after 30 days.

Robbing still remains plausible.

CVB

P.S. Just found this link that suggests a prepicted phoretic period of as low as 3 days but actual phoretic periods of from 4.5 to 11 days ( of 7 samples, 2 values were about 4.5 the rest were over 5 and up to 11 days)

 

[Erichalfbee]

Mine is 2/3rds along a line of 12. All the others have reasonable mite drops on treatment and 4 vapes each will probably do for them. But this one!

I don't have a sublimox but I sure wish I could borrow one. Fifthvape ladt night and I have a drop of 500 overnight. That's nearly 4000 in just over 2 weeks

 

[Eyeman]

Where did you find that information? Zachary Huang here says "The phoretic stage lasts about 5-11 days when there is brood in the colony." so the 5 day figure appears to be a minimum, not an average. This paper says 4.5 to 11 days. The usual 4 treatments, 5 days apart should work but clearly, in some cases it doesn't. Maybe 5 treatments, 4 days appart will do it.

The robbing of an infected colony remains a possibility. My suggestion of mites in the extremities of the hive escaping the OA might be plausible with a heated pan-type vapouriser but Beef's Sublimox would produce so much vapour, under pressure that nothing, even in the corners, is likely to escape a coating of OA crystals.

I seem to remember reading some research a few months ago that counted mite drop after OA vapourising treatment and that suggested that OA was active in the hive for about 30 days, if memory serves. I recall seeing a graph of cumulative mite drop that tapered off after 30 days.

Robbing still remains plausible.

CVB

P.S. Just found this link that suggests a prepicted phoretic period of as low as 3 days but actual phoretic periods of from 4.5 to 11 days ( of 7 samples, 2 values were about 4.5 the rest were over 5 and up to 11 days)

THis was from a recent coment by Randy Oliver:

The amount of time that a mite spends in the phoretic phase appears to be a
function of the ratio between the adult bee population and the number of
8-day larvae in the hive (refer to Boot's studies). A mite can be phoretic
for less than a day, or for hundreds of days. Based upon my modeling (and
hard data collected in the field) the phoretic phase typically AVERAGES
around 5 days during much of the summer.

At 5 days of phoresy, the mite repro cycle would be 17 days, of which 12
take place under the capping. Thus, 5/17 of the mites would be phoretic at
any time. In actuality the percentage would be higher, due to the
additional daughters emerging. My modeling (and hard data) indicate that
roughly 50% of the mites are typically phoretic at any time in late summer,
prior to serious reduction in broodrearing (as low as 20% may be phoretic
at swarming time in spring).

Thus, an oxalic vaporization in late summer, with 90% efficacy, would be
expected to kill only around 45% of the mites in the hive. And if repeated
at 7 days (assuming the OA being active for 3 days), for 4 days a
proportion of the emerging mites could reenter cells without being hit by
the acid.

Nancy's data supports this (Nancy, I'd love for you to send me your data).
We see the same with sugar dusting--it's effective only if repeated at
intervals of only a few days.

 

[Beefriendly]

Trust me it does get less with time....now less than 100 in 48 hours.

 

[Eyeman]

Came across a trial where the effectiveness of OA vape was reduced when there was significant brace comb. Makes sense that the vapour can't circulate as well.

 

[3bees]

One of mine is getting a fifth!

One of mine is on it's 8th...now dropping less than 200/ 48hrs post vape....another few vapes should sort them.
I think they were dead really but hadn't realised it....must have dropped over 5000 mites in the last 40-45 days. Queen still laying...

Surely this goes to show how ineffective vaping is?

 

[Erichalfbee]

Surely this goes to show how ineffective vaping is?

I would agree if it were all the colonies but it is only one of eight. This colony has had a high drop right from the start and continues to do so.

 

[Beefriendly]

If killing 1000+ mites in 48 hrs is inefficient..... I'd be interested in what you know is more efficient.
Please tell.

 

[Erichalfbee]

If killing 1000+ mites in 48 hrs is inefficient..... I'd be interested in what you know is more efficient.
Please tell.

Indeed. It's the colony that's inefficient not the oxalic delivery

 

[charlievictorbravo]

Like others on this thread, I've a problem hive that refuses to give up its mites. It's just had its sixth 5-day vape (2.5 gm of oxalic-based product) from under the OMF and it's still dropped 61 mites in 24 hours.

Possible reasons for continued high numbers of mites:

1. they're robbing out a heavily infested hive
2. the foundress mites are not taking their statutory phoretic breeding break and on emerging from one cell nip into another straight away and are thus not available to be zapped by the OA
3. there are mites in the extremities of the hives that do not get a dose of OA vapour and the vapour cloud swirls around the hive after a treatment

You're welcome to add to the list of possible explanations.

Below is a graph of the drops from this hive in relation to OA treatments - the last count (61) was Saturday 16 September. Just under 2000 mites dropped since the start of treatments.

 

[JWF]

Like others on this thread, I've a problem hive that refuses to give up its mites. It's just had its sixth 5-day vape (2.5 gm of oxalic-based product) from under the OMF and it's still dropped 61 mites in 24 hours.

Possible reasons for continued high numbers of mites:

1. they're robbing out a heavily infested hive
2. the foundress mites are not taking their statutory phoretic breeding break and on emerging from one cell nip into another straight away and are thus not available to be zapped by the OA
3. there are mites in the extremities of the hives that do not get a dose of OA vapour and the vapour cloud swirls around the hive after a treatment

You're welcome to add to the list of possible explanations.

Below is a graph of the drops from this hive in relation to OA treatments - the last count (61) was Saturday 16 September. Just under 2000 mites dropped since the start of treatments.

A few things that may or may not be worth considering :

1. If they're on two boxes, is it worth splitting the boxes and inserting the vaporiser in between the boxes to ensure that the top box gets a good dose.
2. If you're vaping through an OMF then to eliminate the chance of this particular floor knocking out more OA than others, vape via the entrance. Put the vapouriser to the side of the hive if you're concerned about affecting the brood area which is likely to be central.
3. Increase the dose - I think it was the LASI research that showed doses up to 4.2g had no negative effect

 

[3bees]

If killing 1000+ mites in 48 hrs is inefficient..... I'd be interested in what you know is more efficient.
Please tell.

It is your posts that suggests vaping is an ineffective treatment. I would not like to disrupt my colony(s) eight times for treatment - this seems an extraordinarily high level of stress to put your bees through at this time of year.