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BARBARA J. CAMPANA(4) and F. E. MOELLER(5)
ABSTRACT
Caged colonies of Apis mellifera L. fed diets of bee-gathered
pollen from each of 5 plant sources were able to rear brood for
as long as 45 days. The number of bees reared depended more on
the amount of food consumed (preference) than on the nutritive
value (number of bees reared per gram of pollen consumed).
Pollen is the primary source of protein, fats, vitamins, and
minerals in the diet of the honey bee, Apis mellifera
L., and provides all the nutritive elements necessary for life
when it is ingested along with nectar and water. However, in
any study concerning the nutrition of honey bees, the interaction
between larval and adult honey bees is a prime consideration
because newly emerged adults must consume pollen during the 1st
10 days after emergence. Without this initial pollen, the brood rearing ability of these bees
is drastically impaired (Haydak 1934, 1935, 1937) since the glands
responsible for producing the food fed by nurse bees to the larval
honey bees remain underdeveloped and nonfunctional.
Haydak (1935, 1949) and Back (1956) found that honey bees maintained
on marginal or submarginal (in nutritive value) diets could begin
to rear brood, but this ability rapidly diminished with time
as some essential nutritive factors present in the newly emerged
honey bees were exhausted and not adequately replenished by the
food source (Hagedorn and Moeller 1968). Therefore, normal brood
rearing can occur only when the diet consumed by the nurse bees
is sufficient in essential nutrients. However, diets consisting
of the pollen from different plant sources may have different
nutritional value for the honey bee (Todd and Bretherick 1942,
Auclair and Jamieson 1948, Weaver and Kuiken 1951). Investigators
have therefore attempted to discover the differences in the nutritive
value of pollen from various plant species (Maurizio 1950, Wahl
1954, 1963). The experiments reported here were made in 1973
in an effort to add to the information obtained in the previous
studies.
MATERIALS AND METHODS. - Characteristically, honey bees
gather mixtures of pollens from many sources but when one source
becomes especially abundant , they may gather from that source
almost exclusively. By watching for such periods, which may last
for only 1 or 2 days, we were able to define the sources and
to obtain pure pollen. The pollen used in our experiments was
trapped (Schaefer and Farrar 1946) and frozen during spring and
summer of 1971 and 1972
as it was collected by bees from 5 groups of plants (willow,
Salix sp.; sweet clover, Melilotus sp.; boxelder,
Acer negundo L.; blackberry, Rubus allegheniensis Porter;
and fruit bloom, Prunus sp. and Pyrus sp.). The
control diet was made of pollen, collected in 1972, from mixed
sources. Before the test, 1/2-lb (227 g) cakes of each pollen
type and of the mixed pollen (control) were prepared by combining
the pollen (34.4%) with sugar (60.0%) and water (5.6%). The cakes
were kept frozen until fed to the bees.
In the summer of 1973, twenty-four 2-lb (ca. 7000 bees) packages
of bees (provided with a hybrid laying queen of genetically uniform
stock) were hived in single-story 12-frame hives that contained
no pollen or honey. Thus, no food remained in the combs. The
24 colonies were randomly located in one of six 10x10-ft Saran
screen cages 7 ft high, 4 hives/cage. The separate groups of
4 cages each received one of the experimental diets (pollen cakes)
plus 5-lb cans of 67% sugar syrup containing 5 g of fumagillin/gal
of syrup for control of nosema as needed. Syrup feeding was discontinued
when an excess had been stored by the colony. A pan containing
water and a sponge also was provided in each cage.
As bees for this test were obtained, they were of various ages
representative of the normal colonies from which they were taken.
They were uniformly mixed and 2-lb packages prepared from them.
Thus, every unit had bees of the same ages and condition, numbers,
and stock.
The area of sealed brood in each colony was determined as described
by Moeller (1961) on the 20th, 31st, and 45th day after installation
of the bees, times that coincided with the emergence of new adults.
(Colonies maintained on the fruit bloom pollen diet were terminated
following the 2nd sealed brood count due to an insufficient amount
of pollen diet.) Also, after the 3rd and final brood count, any
remaining cake was removed from the colonies and weighed to the
nearest 0.1 g. Then the total amount of pollen consumed by the
bees maintained on each of the pollen diets was calculated based
on the pollen content of the cake. In addition, the cells of
sealed brood were calculated from each count of square-inch brood
area.
The number of cells of brood reared per gram of pollen consumed
was then obtained by calculating the number of cells of sealed
brood produced for the total 45-day test period and dividing
this by the amount of pollen consumed during the test period.
Comparisons were made between
all treatments for the 3 factors by using a completely randomized
design (Steel and Torrie 1960). Analyses also were conducted
on the total amount of sealed brood produced by bees maintained
on each diet and on the brood production efficiency of the diets.
When significant dlifferences were found in the F values of the
analysis of variance, comparisons between the means were made
by using the Waller-Duncan multiple comparison procedure (1969).
RESULTS. - Table 1 summarizes
statistical analyses. All values are the mean of 4 replicates.
Plainly, more bees were reared by honey bees maintained on sweet
clover pollen than were reared by bees maintained on any other
pollen. However, fruit bloom was not significantly different
from clover to the extent that data could be obtained for fruit
bloom. Values for cells of sealed brood reared per gram of pollen
consumed figures indicate the relative nutritive value of each
pollen diet. Diets high in efficiency were fiuit bloom, boxelder,
and the mixed pollens.
The calculated amounts of pollen consumed per day indicate preference
for a particular pollen diet because of the uniformity of test
colony conditions. The most preferred of the diets tested was
sweet clover pollen followed by fruit bloom pollen and mixed
pollen.
The bees were able to rear brood throughout the 45-day test period
while they were maintained on each of the test diets. However,
the dlifferences in the amounts of brood reared and in the efficiency
of the diets were large. For example, bees maintained on fruit
bloom and boxelder pollen were able to rear more bees per gram
of pollen consumed than bees maintained on the other diets; however,
the colonies maintained on fruit bloom and boxelder pollen did
not produce the most bees. Instead, the colonies that consumed
more pollen were able to rear more bees. Preference is therefore
of greater importance in building colony populations than is
nutritive value provided, of course, that the diet does not lack
any important nutrients. Continued investigations into the nature
of preference would be useful in developing a diet that was both
nutritious and preferred by the honey bees.
ACKNOWLEDGMENT. - We thank Emmett Harp, ARS, USDA, for providing the honey bee stock
and for his suggestions and interest and Richard Smith, ARS,
USDA, Research Geneticist, Madison, Wis., for his guidance in
statistical procedures.
(1)
Hymenoptera: Apidae.
(2) Research supported by the College of
Agricultural and Life Sciences, University of Wisconsin, the
Fred W. Mack Trust Fund, and the Agric. Res. Serv., USDA, Madison,
Wis. 53706. Received for publication June 9, 1976.
(3) Mention of a proprietary product does
not constitute a recommendation by the USDA.
(4) Dept. of Entomology, Univ. of Wisconsin,
Madison 53706
(5) Agric. Res. Serv., USDA, Madison, Wis.
53706
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| 1963. Vergleichenda Untersuchungen uber den
Nahrwert von Pollen, Hefe, Sojamehl, und Trockenmilch fur die
Honigbiene Apis mellifica: ein Beitrag zum Eiweiss- und
Vitaminstoff wechsel der Biene. Z. Bienenforsch. 6: 209-80. |
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Reprinted from the
JOURNAL OF ECONOMIC ENTOMOLOGY
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