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by NORBERT M. KAUFFELD**
Bee Breeding Research, Agricultural Research Service,
United States Department of Agriculture,
Baton Rouge, Louisiana 70803 U.S.A.
Summary
In a test during fall and winter in Louisiana, brood rearing
was continuous in colonies of honey bees, Apis mellifera L.,
with uncaged queens and the populations increased throughout
the test. In similar colonies with caged queens (brood rearing
was held at a drastically reduced level), the populations had
decreased rapidly by April. Pollen storage increased in the colonies
with uncaged queens, but the increase in those with caged queens
was not statistically significant. The relationship of stored
pollen to brood rearing in the colonies with uncaged queens was
significant at the 0.1 per cent level. Honey storage decreased
in both groups.
Introduction
During the 1960's, beekeepers in Louisiana and Texas complained
about the fall and winter losses of bees in their apiaries (the
so-called "disappearing disease").
Oertel (1965) noted that the "disease" occurred in
Louisiana from late September to early January when colony populations
literally disappeared within a short time; only a "handful"
of bees was left; honey stores were present; small amounts of
pollen were sometimes present although pollen was generally absent;
and brood rearing was almost nonexistent. He found that his checks
for pesticide residues were negative and also observed that there
were no samples of dead bees with which to conduct any analysis
for (Nosema) disease. Williams and Kauffeld (1973) noted that
the loss of bees in three commercial apiaries occurred during
February which was later than the losses of bees during the 1960's.
Since the loss of large numbers of colonies still recurs from
time to time, we set up an apiary to observe the differences
in colonies of bees with restricted and unrestricted broodrearing
during fall and winter months in the Gulf Coast region. The effect
of different food treatments on the population, amount of stored
pollen and its relation to brood rearing, and consumption and
storage of honey in the colonies from December to the end of
March were also to be observed. It was hoped that the results
would show the importance of continued broodrearing during the
winter months in this region.
Methods and Materials
In October 1970, 24 colonies in standard
Langstroth 2 - broodchamber hives (outside dimensions: 51.4 cm,
w. 42.2 cm, h. 24.1 cm) were selected for this test from one
of our research yards, and frames with brood, pollen, and honey
were shifted between colonies to equalize the amounts in each
as much as possible without recording the square inches of pollen,
honey, and brood in each. All the queens in the test colonies
were sisters (artificially inseminated) and were produced by
this laboratory. The populations of the colonies from the beginning
(12/10/70) to the end (3/25/71) of the test were determined by
counting the number of frames covered by a single layer of bees
on both side (approximately 1,900 bees; CO2 treated; counted).
All colonies were observed for their acceptance of the newly
introduced sister queens, queen egg laying, and egg viabilities
(90-100 per cent) before the first data were taken on December
10, 1970. From early October to December the populations of adult
bees in the colonies changed to that of the new queens.
The test was set up as a 2-3 factorial experiment in which the
24 colonies were randomly divided into two groups of 12 colonies
each, one with the queens free, so they could lay eggs and brood
rearing would be continuous throughout the test, and the second
with the queens restricted. The queens were restricted with a
wire screen push-in cage with one side made of queen excluder
material so bees could enter the cage to feed and groom the queen.
However, these queens in the second group could lay a maximum
of only 25.8 cm2 (4 in.2) of eggs (brood). Thus, these colonies were
forced into conditions that prevail in the north in October when
egg laying and brood rearing most generally stop.
Each of the two groups was then subdivided into three treatments,
each of which was replicated four times.
The three treatments used with both groups of 12 colonies consisted
of the following:
| 4 |
colonies that received no
feeding |
| 4 |
colonies that received 226.8
gr (1/2 lb) cakes of pollen + Drivert feed. Drivert is composed
of 92 per cent finely pulverized sucrose plus eight per cent
invert sugar. |
| 4 |
colonies that received 226.8
gr (1/2 lb) cakes of soybean flour (95 per cent protein) + Drivert
feed. |
The pollen and soybean flour cakes were
mixed with Drivert sugar at the rate of 40 per cent pollen or
soybean flour (95 per cent protein) and 60 per cent Drivert and
fed every two weeks. The 226.8 gr (1/2 lb) cakes were not intended
to be a measure of the total amount that the bees would have
eaten within a two-week period, but rather a measured amount
to act as a stimulant for brood rearing.
Data Collection
The data collected consisted of measurements
of the square inches of brood, honey, and pollen every two weeks
by means of a grid with 2.54 x 2.54 cm (1 in.) squares. However,
inclement weather that occurred during the winter sometimes caused
a slight change in the dates for data collection.
Results
The data in Table One indicate that pollen storage increased
generally throughout the test in the two groups of colonies with
uncaged (continuous brood rearing) and caged (very little or
no brood rearing) queens. Analysis of variance indicated that
variability in the amount of pollen storage from the start of
the test (12/10/70) to the end (3/25/71) with uncaged queens
was significant at the 5 per cent level whereas the caged
group did not show a significant difference in their pollen
storage. The amount of pollen stored fluctuated in all three
treatments of the group with uncaged queens.
Table One also
shows a significant decrease in the amount of stored honey throughout
the test in both groups of colonies. The group with caged queens
showed a greater amount of stored honey for each treatment at
the end of the test than the group with uncaged queens. This,
undoubtedly was the result of less brood reared and the steady
decrease in poptilations of the latter.
Analysis of variance for data (Table One) indicated a highly significant
difference in the amount of brood between the beginning and end
of the test for all treatments of the group of 12 colonies with
uncaged queens. There was a high correlation between the amount
of stored pollen and brood rearing in the group with uncaged
queens.
Discussion
The primary aim of the test was to determine
how long honey bee colonies with populations of young bees could
be maintained in Louisiana with almost daily foraging from October
to March when brood rearing was restricted (only about .12 dm2 of brood
emerged every three weeks). The October population of all colonies
in both groups covered slightly more than 10 Hoffman frames of
a Langstroth hive; the March populations of the two groups were
very different. Colonies with uncaged queens had increased in
population to cover an average of 14 frames (continuous brood
rearing and subsequent replacement of old dying bees by young
bees). Colonies with caged queens (brood restricted) had an average
of only 2.2 frames of bees. Two weeks after March 25, 50 per
cent of these colonies were dead even though food supplies were
present in the hives. March conditions in these colonies were
similar to those associated with disappearing disease in the
southern states.
In the Gulf Coast States, bees probably do not live as long during
winter months as those in the north because of the almost constant
foraging activity for food supplies. Therefore, the maintenance
of brood rearing would be desirable during winter months within
colonies in Louisiana so that a constant supply of young bees
will replace those that are dying. Under northern conditions
the majority of adult bees live from October to March because
of the reduced field activity. Brood rearing which starts around
January in the north is carried on with pollen and honey that
were stored during the previous fall. Stimulative feeding is
often practiced to offset a lack of stored pollen (Farrar 1968).
The colonies which received no feed besides what they collected
from the field and those that received a diet of pollen and drivert
showed increases in the amounts of brood and stored pollen. Those
that received soybean flour and drivert had less brood and stored
pollen than the other two groups.
ACKNOWLEDGMENT
Grateful thanks are extended to Dr. Barton Farthing, Head, Department
of Experimental Statistics, Louisiana State University, for his
help in the statistical analysis and to Dean Brister and Al Raby
of this laboratory for their technical assistance in the collection
of data.
REFERENCES
Farrar, C. L. 1968. Productive
management of honeybee colonies. Am. Bee J. 108(3-10)
: 20.
0ertel, E, 1965. Many bee colonies die of an unknown cause.
Am. Bee J. 105(2): 48-49.
Williams, J. L. and N. M. Kauffeld. 1973. Winter conditions
in commercial colonies in Louisiana. Am. Bee J. 114(6):
219-221.
FOOTNOTES
* In cooperation with Louisiana
State University Agricultural Experiment Station.
** Now Research Entomologist, Bee Research Laboratory, ABS-USDA,
2000 East Allen Road, Tucson, Arizona 85719.
Reprinted from December, 1975, American
Bee Journal VoL 115 (12): 480, 481 and 490
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