On Wed, 11 Nov 2020 11:01:34 -0500, Scott Langlais <[log in to unmask]> wrote:
>Our local beekeepers (RI/MA) are reporting alarmingly high mite counts post-treatment this year.
>
>A few questions have arisen as a result of this.
>
>1) What is the optimal time after treating to retest for efficacy?
>
>2) Is there any way to quantify reinfestation via robbing/drift?
Myself (15 hives) and a beek up the road (4 hives) have a record of clean hives through Sept. Either treating with Formic just in case in Aug/Sept, or checking mite counts in Aug and treating or not as dictated by the results. Less than 12 mites in 300 (alc wash), I wait until fall to treat. So, we know our hives are clean enough come the end of Sept...
Then we treat in Oct with OAV. In northeast OH, the only prudent way to know the mite infestation levels in fall is to treat and check mite drops after treatment - we are not pulling frames to do alcohol washes after Sept.
My buddy's 4 hives all had very high mite drops - 1000+. He doesn't really count them but can tell the difference between a dusting of mites and a lot of them.
I had a range of mite drops post OAV (2nd treatment), from 800 to 50. I'd expect that if I got 90%+ of the mites in the previous treatment, I shouldn't see 800 mites falling with the second treatment - that number is a little lower than the mite drop for the first treatment, but not 90% lower.
A. Interpretation. I'm interpreting a mite drop above 50-100 for a 2nd OAV to be evidence of continuing reinfestation by mites incoming from MY bees robbing a dying hive. Stupid bees.
I also interpret a mite drop of more than 300 for the first OAV to be evidence that they found more than honey in a dying hive...
B. Management. To protect my hives from a possible influx of mites brought back by house bees robbing, I assume all hives are going to engage in this behavior. I think of it as vaccinating them.
I treat in early Oct, then about every 3 weeks until early/mid Dec, after a series of fly days. So, we just had a nice week of weather, great opportunities to go robbing, so now with the weather turning, time to treat.
I treat until mite drops are at 50 dead mites 48 hrs post treatment 2 treatments in a row.
If a hive was clean, and goes robbing in Oct/Nov, they will die by early Jan. But if they are treated in starting in mid Oct, they will be fine. Last year, a few hives had a cumulative mite drop in fall of over 3000 mites. They were very strong this spring, as strong as their neighbors in the apiary that did not have such high fall drops.
I found the hives that were throwing all the mites last year - a mile due west. Between my mite drops and my other buddy's up the road with 4 hives, we figured at least 20000 mites were thrown from those 2 hives.
I made friends with the beekeeper where the mite bombs came from (he doesn't go into the hives at all). I have 2 hives there that were too many for my apiary, and I treat his and my hives, so no more mite bombs.
That's one perspective on the presence (and potentially fatal consequences) of mite immigration from your bees gone robbing.
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