Colonies of honeybees gather and consume pollen and
nectar; the pattern of collection of these substances,
certain aspects of their composition, the individual pollen
types utilised and the effect of variations in the pattern
of nectar collection on colony development have been investigated
in the South-East of Scotland. A very small proportion of the available flora is utilised by bees for pollen
gathering and an even smaller number of pollen types are
collected in any quantity. The mean active pollen gathering
period is only between 107 and 120 days long. Variability
between colonies rather than between sites accounted for
most of the differences between the amounts of pollen trapped.
Most pollen and most pollen types were gathered when brood
rearing was at its peak. Mixed woodland was the habitat
from which bees gathered relatively most pollen and sycamore
was the best individual source; less pollen was collected
from raeadowland and arable land; in the former white clover
was the best source and cruciferous weeds in the latter.
The same pollen types were harvested from the one site during
the 4 years in which it was investigated although individual
colonies there showed slightly different preferences.
Trapping pollen from colonies did not affect the amount
of brood reared although it appeared to influence the winter
survival and also produced a few other temporary effects.
A variable proportion of the total pollen being harvested
appeared to be culled from the colonies throughout the
active season by the traps.
Significant relationships between the colony weight
and the amount of honey in store throughout the active
season (r = 0.94) allowed a study of the nectar flows in the
area to be made by direct weighing of the colonies in their
hives. This established that good nectar flows occurred
on the Lothians' coast in early summer and in the upland
area to the south of this coast in Enid and late summer. The
first of these produced transient effects upon the colonies
while the second affected the amount of honey stored (36 kg
stored in upland colonies compared with 11 kg in the coastal
ones) and the brood reared.
All the colony characteristics measured with the exception
of honey in store reached their maxima about mid-summer
when they averaged 37,000 adult bees, 2.7 kg stored pollen
and 21,000 brood. Larger colonies stored most honey by the
end of the season and reared most brood; but the only significant
correlations were those between the pollen trapped
per day and the brood, and between the mean pollen in store
and the brood.
As a result of chemical investigations the results
mentioned in this next section seemed most worthy of note.
Fresh pollen contained 27% water. Wooden traps produced
pollen in a much more satisfactory state than metal ones.
The mean lipid and ash content of the pollens was low.
About 31% of the pollen consisted of sugars, which are valuable food materials for honeybees. The gross energy of
pollen was high (5,500 kilo calories per g). Pollens
contain a low quantity of nucleic acid. Most of the
nitrogen content of pollens after hydrolysis was in the
form of amino acids. The various types of pollen showed a
close similarity in the relative amounts of amino acids
which they contained with the exceptions of serine, cystine
and histidine. Analyses of honeybee carcasses indicated
that their amino acid contents were very similar to those
of the pollens which are therefore nearly ideal sources of
these nutrients for bees. Pollens were also found to be
better sources of the minerals Na, Mg, K and P for honeybees
than honey in which the cation pair K and Mg were closely
related and Mg was most affected by the other ions