Varroa research digest

[Poly Hive]

From BeeL

An upcoming issue of the Journal of Invertebrate Pathology will focus on honey bee disease. Here are some excerpts from a summary on varroa control:

> Trapping of mites in worker or drone brood: Up to 95% efficacy in otherwise broodless colonies; up to 50% mites removable with solely drone brood extraction; no detrimental effect on colony development

> Use of wire netting bottom boards: Probably no or only small-scale effect on mite population, but as ’natural mite downfall’ a valuable tool for beekeepers to monitor treatment-thresholds

> ’Energy waves’ e.g. ’Bio-Energetic Bee-Vitalizer’ activates grooming-skills of not tolerant bees: Anecdotal reports from hobbyists, effect not scientifically affirmed

> Powdered sugar: After direct dusting, up to 99% of the mites can be removed from the bees in laboratory assay; in the field trial low efficacy even if dusted every 2 weeks for 11 months

> Water -- Swarms are completely plunged for 5 min: Under controlled conditions ineffective

> Ultrasound: No effect on bees or mites under controlled conditions

> Reduced cell size: Promising reports from hobbyists, but under controlled conditions no effect on reproduction or mite population growth

> Rotation of brood combs: Reports of sweeping effects could not be affirmed scientifically

Quoted for review purposes only. SOURCE: Rosenkranz, P., et al. Biology and control of Varroa destructor. J. Invertebr. Pathol. (2009)


PH

 

[RoofTops]

I think these confirm my own feelings but I am unsure what is meant by "in otherwise broodless colonies"? Does this mean a shook swarm when all the brood is removed? I and others I know have certainly found a shook swarm early in the year has a dramatic effect on the mite populations and the colony develops at least well if not better than it would otherwise. Anecdotal evidence perhaps but my strongest colony last year was one I had done a shook swarm on.

 

[tonybloke]

I think these confirm my own feelings but I am unsure what is meant by "in otherwise broodless colonies"? Does this mean a shook swarm when all the brood is removed? I and others I know have certainly found a shook swarm early in the year has a dramatic effect on the mite populations and the colony develops at least well if not better than it would otherwise. Anecdotal evidence perhaps but my strongest colony last year was one I had done a shook swarm on.

perhaps by the term 'broodless colony' they mean a 'collected swarm' ?

 

[oliver90owner]

Yes, I would think so. That is what I am hoping to do with my colonies early next spring. Most of the brood will be transferred (with it's varroah loading) to some isolated colony(ies) and that (those) colony(ies) treated appropriately later on. That way if late, most of the brood will not be wasted, only the first from the fresh comb - and that may be old super comb, if it works out, rather than a hole in a 14x 12 frame.

Regards, RAB

 

[Finman]

.the first case is a dutch method.
You have a broodless colony and you give there one larva frame. During one week mites go into larva cells before capping. Then you take the frame away.

 

[BKF Admin]

Never read of that idea before,interesting Finman.

 

[RoofTops]

The same idea is done with a shook swarm and is known as a "Bait frame".

 

[Heather]

The fact that many bee keepers are being told to sacrifice drone larvae to control varroa - is this having any effect on poor queen matings as drone population is diminished - or is the sacrifice minimal?

 

[RoofTops]

If everyone did it there would have to be an effect, but only the minority carry out drone brood removal.

 

[oliver90owner]

Heather,

Two ways to look at it.

If the drone likely to be badly affected by varroa mites - you might as well remove it. A lot of the drones are likely to be sub-standard and the mite population increase will accelerate. No-win situation, if you leave it to hatch.

A short frame dropped in the bood nest will nearly always prompt drone comb building. Chop out the first capped patch and monitor subsequent patches if you are wanting to proliferate that queen's genes. Remove, if still a bad infestation; leave if not. Win-win situation.

If drone brooding early for queen rearing, you just have to put up with the extra varroa load and treat later.

Your choice, but continual monitoring for varroa (mite drop and drone larvae infestation) will give you a good feel for the health of the colony as the season progresses. One should never get to the stage where a lot of wing damaged larvae are hatching - BTDT in my early days of beekeeping. Know much better now.

As an example, I know that one of my colonies has very little mite load - been watching it with interest all season. I have done very little apart from monitoring, and whacking it with thymol, more as a precaution. Her mother was in a similar situation last year, got the apiguard treatment, but virtually no mite drop, and only a few mites in drone brood towards the end of April this year (no other treatment). That colony will most certainly not be treated with oxalic acid this winter. If it is a winter casualty I am confident it will not be due to a high varroa count.

That colony is the exception.

Regards, RAB

 

[Finman]

The same idea is done with a shook swarm and is known as a "Bait frame".

as far as i know the origin is a dutch university and i have told it many times in british and us forums. And british have invent it now. Good! Sorry. .