Adony Melathopolous assumed a bee flight muscle temperature lower
threshold of 25 C, and predicted a sustained flight temperature
threshold of 12 C, with flights below that temperature, dependant on
heat retained from a visit to the cluster.
The reasoning is fine, but since in this area we have a lot of days when
the temperature never gets to 12 (most of our spring build up), yet
there is a lot of sustained bee flight, some of the thresholds must be
different from those Adony used.
Perhaps we'll get some actual measurements from someone, but I could add
a few impressions or observations:
- at -10 C bees that fly out from an exposed cluster will shut down and
drop out of the sky after 5 or 10 seconds (my impression, not timed)
- when hives are opened to feed bees in the fall at 0 C, bees will fly
from the cluster quite actively and keep it up for minutes (perhaps
they're creating heat as fast as they're loosing it). If they land on a
bee suit they will cluster, and when brushed off they might fly.
I've seen bumblebees foraging at less than 5 C (though they might
experience warmer temperatures in the sun, especially in those blossoms
that track the sun and provide a parabolic solar heated platform)
- hives put out in "spring" (2 weeks ago here) at 5 C can have lots of
flight, apparently sustained although a lot of bees end up on the snow.
However, a bright sun on a still day might add quite a bit of heat to a
dark bee.
SEASONAL CONDITIONS: Dawson Creek 55 deg N Lat April 24
Well, I've bit my tongue and held back any response to the reports of
honeyflows and swarms from S Carolina, but I guess it's time to report
that winter is over here. We had an impressive blizzard April 2, lots of
drifting snow, but the daylight hours are too long to allow it to stay.
About April 15, the temperature stayed above freezing through the night,
for the first time since about October 20 (nearly 6 months). Flat open
ground became snow free over the past 10 days, south facing slopes have
a few blades of green poking through the dusty beige dried grass. Shaded
spots still have piles of icey snow. Pussy willows are out and I've
heard of some pollen being spotted, I guess from a particularly sunny
spot. At the base of a southern wall, I even saw a dandelion blossom
open!
This isn't a complaint (well maybe it is, but I know that won't help).
The remarkable thing is that the honey bee colonies that look so pitiful
now, will recover and build up to the point that 150 lb of honey can be
harvested from them.
Busy days ahead
Kerry Clark, Apiculture Specialist
B.C. Ministry of Agriculture, Fisheries and Food
1201 103 Ave
Dawson Creek B.C.
V1G 4J2 CANADA Tel (250) 784-2231 fax (250) 784-2299
INTERNET [log in to unmask]
|