I happened to come across this paper on Disappearing Disease from 1984,
quoted below:
159553658.pdf (core.ac.uk) <https://core.ac.uk/download/pdf/159553658.pdf>

"Bees up to l day old were collected (from caged brood) at the dates given
below. The average time required for 50% mortality in 3 samples of 50 bees
from each of the 8 colonies are the following with their standard errors:
 1977
 First test, Aug. 4: 20.6 days ± 1.3
 Second test, Sept. 23:   22.5 days± 0.7
1978
 Single test, June 16: 42.3 days ± 1.3
Why bees should live twice as long in 1978 as in 1977 is not clear. All
conditions of the experiment were similar as far as we can judge, except
the pollen supply and the time of test-different dates in two different
years. Colonies had about twice as much pollen in 1978 as in 1977, and
amount of pollen per comb of bees in the early part of the year was greater
in 1978 than in 1977."

Of additional interest are the high rates of diseases and attempted
supersedure.  And "From this evidence, one can conclude that none of these
so-called stocks were really genetic stocks showing genetic homogeneity
among their colonies."


Randy Oliver
Grass Valley, CA
530 277 4450
ScientificBeekeeping.com


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