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Date: | Tue, 1 Dec 2020 00:16:41 -0500 |
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For those interested in Meghan's reference for the screened hive vs standard wood Report 169 USDA. Randy O has it linked on his website - http://scientificbeekeeping.com/scibeeimages/Moeller-1978-Overwintering-of-Honey-Bee-Colonies.pdf
Very good read.
I would say Varroa (w/ associated viruses) and Nosema Ceranae (immune system impacts along with potential viral interactions) are the game changers that were not present during many of these older studies. CCD is still being thrown around as a cause in the US (likely caused by a cocktail of issues). Severe Nosema C in winter here will depopulate a hive very quickly. I see the impact because bees don't fly far at -30C. They drop dead at the hive entrance, where they may fly and die further away in warmer location. I can probably do the math to show the equivalent to -30C in my Insulated hive and how it would be equivalent to a 0 to -10C in a non-insulated hive from a cluster cold stress perspective. No issues with healthy bees but it will likely spell trouble if mite loads are high and/or colony has moderate levels of Nosema.
Photo on left entrance has severe Nosema C (~1 weeks worth of dead bees), Right entrance tests clean
I monitor my dead bees in front of the hive once a month. It helps me understand what they are dying from. I also see if the dead bees were "fat" average abdomens or skinny (pollen deficient). After a while you start noticing how some bees have tiny abdomens. My 1st round in October typically shows medium Nosema C likely due to the older foragers dying off. Nosema levels will typically drop off after that. If I start seeing high mortality like the photo and severe Nosema levels than I know that hive will be in trouble. I have so far kept away from using Fumagilin. In the last 3 years I have only lost 1 hive per year in June to Nosema (1 of 8).
By the way, sorry for the typos on my previous post.
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