Mite levels autumn 2018

For reasons that are not entirely clear the mite levels in my colonies are unusually low this autumn.
By 'unusually low' I mean single figure cumulative drops 7-10 days after starting the autumn treatment.
Is this good beekeeping (Ha! ... didn't think so) or a consequence of the excellent season we've had?

These colonies were last treated in early December 2017 after an extended cold-snap and during a known broodless period with a trickled Api-Bioxal. Almost all have been split during the season, had a nuc with the new queen removed and the remainder re-united back to one box. All are strong colonies, though most have limited amounts of brood at the moment after the Q stopped laying when the flow stopped.

There's been some drone brood removal (to make space, not for mite control), but not excessive and most colonies have foundationless frames which have a much higher proportion of drone brood anyway. Nothing else ... no sugar dusting, no rhubarb leaves over the crownboard, no careful location of apiaries on ley lines ;)

For work we've individually uncapped many hundreds of pupae and not seen a single mite all season.

Many of you will be starting autumn treatment about now ... are your mite levels also unusually low?

yep - same here apart from one colony of yellow bees which arrived as a swarm at the start of june, a real silver spoon as i got 4 supers from them. Mite levels very low all round with Amitraz strips

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Originally Posted by fatshark

Many of you will be starting autumn treatment about now ... are your mite levels also unusually low?

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Mine won't be treated until we get all the hives back from the heather in a week or so's time. Checked a couple of double brood hives with sticky boards. Over 5 days, 1 dropped 0, 1 dropped 3..
Yeah, I know there will probably be 1000's on the first vape :)
But others are also reporting low varroa upon vaping...seems this summer may have worked in mysterious ways.

Or all our Api-Bioxal (ahem!) has become inactive ... ;)

I checked again today and still see v. few mites. Ants aren't taking them as I've got some of Pete Little's excellent floors with tight-fitting Varroa inspection trays. I might pop some Apivar in one to see if anything appears over the next 4-6 weeks.

I seem to have less varroa this year too; Drone uncapping has revealed almost none. There have been suggestions that varroa have lost their potency (especially as they breed with their own siblings so there is little genetic diversity). However I wouldn't rely on that as being gospel. I think this year I certainly witnessed a long cold spell from the 'Beast' and then a poor March where there was little pollen and little brooding. So maybe the varroa just fell off! :)

They've done perfectly well with little genetic diversity so far!
If it was the "Beast from the East" and a rubbish March reducing early season mite numbers it could suggest there are other strategies that could be used to control Varroa.

Mixed results : one with lots (100+) in a week, others with minimal (10-50). Apiguard mainly gone after 9 days treatments - 2nd due next week..
Half my hives have solid insulated floors so no monitoring..

I have some VERY big colonies with a super of honey for winter they appear to be dropping most (what a surprise!).

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Originally Posted by fatshark

They've done perfectly well with little genetic diversity so far!

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True - but I am reporting what I have read (somewhere) which might have been someone else's mad ramblings rather than science!

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Originally Posted by fatshark

If it was the "Beast from the East" and a rubbish March reducing early season mite numbers it could suggest there are other strategies that could be used to control Varroa.

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Some comment that a brood break (swarming) helps bees rid themselves of (reduce levels of) varroa. If bees tend to remove some of the varroa whilst there are no broodcells to hide in, then mite numbers may come down to safer levels.
What we need is an artificial brood pheromone in a bottle that can be used to attract all the varroa to it; then take the bottle away. No need to kill the mites. Simples!

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Originally Posted by Adam

Some comment that a brood break (swarming) helps bees rid themselves of (reduce levels of) varroa. If bees tend to remove some of the varroa whilst there are no broodcells to hide in, then mite numbers may come down to safer levels.
What we need is an artificial brood pheromone in a bottle that can be used to attract all the varroa to it; then take the bottle away. No need to kill the mites. Simples!

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Swarming undoubtedly helps get rid of mites. The swarm leaves with about 25-30% of the entire mite population (which is perhaps surprising when you consider that most people quote ~10% of mites are phoretic ... I suspect this reflects the reduced laying rate of the queen leading up to swarming. Someone smarter than me could model this.). The remaining 75% in the original colony will get increasingly exposed as sealed brood levels decrease (and therefore increasingly removed you'd hope).

Randy Oliver has a great quote about colony splits and Varroa ... Take home message: early splitting knocks the snot out of mite levels.

All my colonies were split this year. Most were either reunited after requeening or used for nuc production. I've been toying with the maths of mid-season treatment on temporarily queenless colonies with the intention of testing things next season.

A nice presentation on brood attractant pheromones ...

https://www.alfredstate.edu/files/do...rk-Carroll.pdf

a bee landed on my knee resting, at the beginning of the week , with a varroa on its back

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Not one of mine ... mine refuse to go "Norf of the river".

However, I've now completed my treatments and mite levels remain vanishingly low.

On a related point ... as part of my day job we've also looked at viral loads in lots of colonies and they're some of the lowest we've ever seen. In some they're bordering on the limit of detection. We're pretty sure this is because the Varroa levels are so low, but still don't have a rational explanation for this. Our management has been the same as previous years - early autumn treatment, midwinter dribble and some drone brood removal (though the latter primarily to make space *, rather than manage mites).

* I use a lot of foundationless frames. Currently I favour those with vertical bamboo skewers. The bees initially build three panels of comb, often alternating worker and drone. During the swarming season I repeatedly cut out and discarded the drone brood. This gave the colony something useful to do and may have helped lower mite levels. The "three panel" foundationless frames make this particularly easy to do ... much easier than those with horizontal wires or nylon ... though they're a bit more fragile in the early stages of being drawn.

It may even have helped delay swarming in some of the colonies though I'm aware of a couple that made a successful escape.

Mite levels are low in colonies from which we removed no drone brood as well.

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Originally Posted by fatshark

However, I've now completed my treatments and mite levels remain vanishingly low.

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Not started treatment yet as just bringing hives back from the moors. Drop counts (inaccurate I know) have been extremely low, so expecting to find similar to most.
Spring was at least a month late around us and I've got no idea how long varroa can exist in the phoretic state. Perhaps this killed many off.
And then followed by a summer that has been one of the hottest on record. Isn't there some guff somewhere about varroa not being able to breed as succesfully in elevated temperatures?
I recall a heated hive being marketed as the "answer" to varroa.
Obviously it wasn't...but perhaps extended heating might be an avenue to explore?