> I figured that I was taking pollen collected
> from my strongest colonies and feeding it
> to small spring clusters so that the relatively
> small quantity of AFB spores in the autumn
> was fed to the relatively small expanding
> clusters in spring.
Yes, this is possible, but given the studies on the books, I would say
"highly improbable". Long story short, a forager can pick up some AFB
spores by brushing against a house bee that has cleaned out an AFB-infected
cell, leave to go forage, and thereby brush/pack some AFB spores into a
pollen pellet that is left in the pollen trap upon its return to the hive,
but this requires at least a low-level, undetected "case" of AFB in that
same hive to start.
The standard statement oft-intoned is "~35 spores will infect a day-old
larvae. 1 spore is enough to infect an hour old larvae." But I do not have
an actual citation for this factoid. (Anyone have one?)
Sharply contradicting the above, Mark Goodwin of the NZ Apicultural Research
Unit fed spores in syrup to colonies, and could only get ABF infections
going In 4 of 5 colonies he fed 5 million spores. Hives fed 50k or 500k
spores remained "AFB-free". So, the threshold for infection is somewhere
between 500k and 5 million spores fed, something you simply are not going to
achieve without transferring infected brood frames between colonies or some
serious robbing of a very weak or deadout hive.
To further debunk, Goodwin also set up pairs of infected and uninfected
hives with sides touching and entrances adjoining. The infected hive had
less than 50 larvae with symptoms. After 5-388 days (average 103 days)
only 2 of the uninfected colonies developed AFB as a result of the drifting
bees.
"The effect of drifting honey bees on the spread of American foulbrood
infections"
JAR Volume 33, 1994 - Issue 4
https://doi.org/10.1080/00218839.1994.11100873
More recently, these guys worked up a model of AFB transmission and
infection, and the narrative lists all the possible mechanisms, even if one
has no interest in the math.
"A Mathematical Model of Intra-Colony Spread of American Foulbrood in
European Honeybees (Apis mellifera L.)"
PLoS One. 2015; 10(12): e0143805
doi: 10.1371/journal.pone.0143805
So I'd wager that the more likely scenario is that your infections were
brought back by robbers of spring dead outs, and your pollen feeding had
nothing to do with it.
That said, do I still clean my hive tools? Yes, I burn off the Propolis
with a torch, and autoclave them weekly at my very understanding Doctor's
office. But would I trap and feed back fresh-frozen pollen? Yes I would,
if it did not sell for such a good price.
Also, you need a USB-based external modem to plug into a phone line with
that MacBook.
Here's one on eBay, still sealed in its little plastic bag for $7.99
https://www.ebay.com/i/362490900082
Non-Apple modems will also work, like the US Robotic 5639, for $26.49 @ B&H
Photo
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