Inside Story of Feeding Sugar to Bees
Transcribed from New Zealand Beekeeper, May 1974, pages 41-43.
The practice of feeding sugar (either dry or as a syrup) is becoming
more and more popular with beekeepers. This trend partially reflects
the increasing price paid for honey, and also the need for extra
winter stores due to the paucity of late autumn and early spring
nectar sources.
Many beekeepers pour the sugar into the hive, close the lid, then
hope for the best. Sometimes when they come back the bees have
converted all the sugar into ripened stores. In other hives, maybe an
adjacent one, the sugar (either dry or in a syrup) is still in the
feeders and could be in various stages of fermentation.
It is a strange fact that two hives can appear equal in bee strength,
brood and stores, yet one will readily store sugar while the other
will not, especially if dry sugar is fed. I wonder if anyone has
noticed any correlation between the productivity of a hive and the
rate at which it stores sugar? In other words does a hive that
produced a good crop of honey, relative to others in the apiary, also
store sugar more readily?
What do the bees do with the sugar?
Bees must invert or "digest" the sucrose molecules, before they can
assimilate them, as well as reduce the water content. In the case of
dry sugar the bees add a great deal of water to the crystal, more in
fact than to concentrated sugar syrups or honey. This will mean the
bees have to make extra foraging flights to collect water. According
to Simpson, food containing more than 50 per cent or more sugar is
diluted first before being ripened.
The enzymes (particularly invertase) which are necessary for reducing
the sucrose molecules are produced in the hypoph-aryngeal glands of
the adult bees. These are the same glands that first produce royal
jelly for feeding larvae and the queen, and are most active in bees
aged 5-13 days. From 17 days onwards during the summer, the glands
rapidly shrink in size, and cease producing royal jelly, but the
amount and activity of the enzymes secreted is increased. Enzyme
production, naturally enough, reaches a peak after three weeks when
the worker bees begin foraging.
In the winter time bees of all ages have large glands rich in
invertase. Effect of disease on the hypopharyngeal glands: Nosema
disease is known to affect the glands of bees and reduce the amount
of royal jelly produced. Nosema also affects the levels of protein
and amino acids in the blood but it doesn't influence the levels of
blood sugar at all.
The effect of enzyme production on honey yields: Some recent research
work carried out in Russia suggests that the honey production of a
hive could be related to the efficiency of enzyme production by the
bees and that this efficiency varied, from hive to hive. Naturally
the strongest hives, with bees producing most inverting enzymes also
produced the most honey.
Storage of sugars in the body:
Bees have the ability to store surplus protein in their body fat and
also in their blood. However, they do not have any storage organs as
such, for sugars. Rather the sugars remain free in the blood and the
levels are not regulated as in mammals, but fluctuate markedly
according to the diet and activity of the bee. Thus, when a bee first
emerges or when it is resting on the comb it has very little sugar in
its blood. However, when it is out foraging, blood-sugar levels
become very high.
Physiological demands on the bees:
Converting sugar into honey and storing it is a very exhausting
process, in terms of energy used by the bees. The bees must first
produce the enzymes, and secrete them, they must suck up the syrup
and invert it, they need to keep the hive temperature high to
evaporate excess moisture from the syrup, as well as secrete and
manipulate the wax to store the honey in.
Let's look at some of the processes involved and see how we can help
the bees to be more efficient. In all these considerations timing is
reasonably important. In most areas April-early May would be suitable
for feeding sugar to winter the bees on.
(a) Inverting the sugar:
We want to get the sugar. inverted and ripened while. the maximum
number of older bees with active glands are in the hive. These bees
are mostly expendable and will not survive long into the winter
anyway. Ideally we want a balance between having enough older bees
but not too many to consume excess food.
(b) Heating the hive:
Bees generate a lot of heat from the sugars they eat. Of this heat
Wedmore calculated that 60-70 per cent is used to heat the bees, 20
per cent is used to evaporate water, and 10 per cent is used to heat
the air, so a significant amount is used solely to evaporate water.
And as warm air is able to hold much more moisture than cold air it
is to our advantage to feed the sugar before the weather gets
excessively cold and damp. The warmer the ambient or surrounding air,
the less energy the bees need to consume solely to keep themselves
warm and evaporate moisture.
(c) Eliminating the water:
The energy required for ripening large quantities' of nectar is
appreciable; for instance Ribbands calculated that the elimination
of each pound of surplus water involved the wastage of 4-5 ounces of
sugar. This is about 25 per cent and approximates Wedmore's figure of
20 per cent. Further the actual consumption of honey also releases
water as the "water of combustion" plus the 17-18 per cent water
naturally in honey, and this too demands energy to get rid of it.
This extra water may be as great as one-half to two-thirds of a pound
for every pound of honey consumed. Some of this water is lost by
evaporation but the great majority is stored temporarily in the
rectum then disposed of during cleansing flights. Again the bees
should have ample opportunity for flying during the period in which
they are ripening sugar stores.
(d) Wax production:
One researcher found that one pound of wax can be built into 35000
cells which would hold 22 pound of honey. Other workers have found
that it takes somewhere between 6-10 pounds of honey to make one
pound of wax. So a significant amount of our original sugar stores
are also going to be used up in producing the wax as well as
maintaining a high cluster temperature needed to manipulate the wax
scales into comb.
(e) Case study:
Let's take an example and see just how much of our original sugar we
can .expect to be converted into sealed stores. Let's feed 4 gallons
of 2:1 or 62 per cent white sugar syrup. This will contain 32 pounds
of sugar at the rate of 16 pound to the gallon and should weigh in
the vicinity of 52 pounds. Assuming our ripened stores will contain
18 percent moisture we have to lose 20 per cent water or about 10.4
pounds of water. Now this represents an elimination cost of nearly 3
pounds of sugar, if 4-5 ounces of sugar, are lost per pound of excess
water. This sugar itself when consumed by the bees will also release
excess water of combustion that will require energy to eliminate.
However, that is getting a bit complicated. Now the bees are going to
use something like 5-9 pounds of honey from sugar to build enough wax
to hold the syrup, although this figure could fluctuate depending on
how drawn out the combs were.
But from our original 52 pounds of syrup we have lost or used up
10.5 pounds. of water, and say 11 pounds of sugar to eliminate the
water and produce the wax. This leaves us with about 30.5 pounds of
ripened stores. As a rough role of thumb in estimating stares
produced from syrup. The final weight of ripened stores in the comb
is slightly less than the weight of dry sugar in the original syrup -
in our case we could expect about 30 pounds of ripened stores from 32
pounds of sugar.
Recommendations: Don't leave your sugar feeding until too late in the
autumn.
Feed while:
There are plenty of older expendable bees with active glands still
present. It is not too cold to secrete wax. It is not too cold or
damp for efficient evaporation of moisture from the hive. There are
still some natural honey stores in the hive.
Remember:
"Bees Do Not Freeze To Death - They Starve To Death".
|
