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Screening of Potential Shrubs for Bee Forage Development
ArticleinJournal of Plant Sciences · October 2017
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Journal of Plant Sciences
2017; 5(5): 160-164
ISSN: 2331-0723 (Print); ISSN: 2331-0731 (Online)
Screening of Potential Shrubs for Bee Forage Development
Tura Bareke*, Admasu Addi, Kibebew Wakjira
Oromia Agricultural Research Institute, Holeta Bee Research Center, Addis Ababa, Ethiopia
firstname.lastname@example.org (T. Bareke)
To cite this article:
Tura Bareke, Admasu Addi, Kibebew Wakjira. Screening of Potential Shrubs for Bee Forage Development. Journal of Plant Sciences.
Vol. 5, No. 5, 2017, pp. 160-164. doi: 10.11648/j.jps.20170505.15
Received: July 22, 2017; Accepted: August 2, 2017; Published: October 26, 2017
Abstract: Availability of adequate honeybee forage plants is very important for honey production. The study was therefore
conducted to screen the best performing bee forages from five plant species with a view to selecting for honey production for
high and mid land agro-ecologies. The planting materials were Vernonia amygdalina, Buddleja polystachya, Callistemon
citrinus, Dovyalis caffra and Chamecytisus proliferus. The species were evaluated based on the number of flower heads per
plants, foraging intensity of honeybees, flowering length and amount of pollen. C. citrinus, C. proliferus and V. amygdalina
were set flower with the ranges of two to three and half years while B. polystachya, and D. caffra didn’t reach to set flower up
to the end of five years. V. amygdalina and C. proliferus provides significantly higher pollen compared to C. citrinus. Average
number of flower heads per plant were highest for C. proliferus and it was significantly different (p<0.05) from the rest. The
flowering time of C. citrinus, C. proliferus and V. amygdalina are almost during the dearth period at which only a few bee
forage plant species in flower around the area. V. amygdalina and C. citrinus was highly foraged by honeybees from 10:00am-
12:00 am, while C. proliferus 10:00 am -2:00pm. C. citrinus has the highest flowering time with duration up to six months in a
blooming state having lots of flower heads and the rest months with few flowers. Generally, the study revealed that C. citrinus,
C. proliferus and V. amygdalina were selected as major bee forage plants. However, it requires further evaluation particularly
on nectar volume and sugar concentration for these plants and their integration with watershed development is recommended.
Since they were flowered in dearth period and their further multiplication is recommended to increase honey production.
Keywords: Shrubs, Flowering Period, Foraging Intensity, Set Flower, Bee Forage
Beekeeping is an incentive for planting trees and
protecting existing trees, because trees are very important for
bees and therefore for beekeepers as well . On top of this
honeybees serve as pollinating agents for numerous species
of plants and contribute to their survival, genetic prosperity
and play a crucial role in the maintenance of ecosystem
services [7, 8, 15]. On the other side, honey bees can benefit
from plants in different ways: some plants can be utilized by
honey bees as food sources (pollen and nectar); honey bees
visit certain plants to gather propolis beside their ability to
recycle previously collected propolis ; some plant cavities
and branches can be used by honey bees as permanent or
tentative nests, respectively. Beside these benefits, some
plant extracts have been used as treatment for honey bee
parasites including; neem oil  and thymol powder .
The success of beekeeping depends not only on honeybee
strains and its management but also on the abundance and
availability of bee floral plants around bee farming area .
Bee forage management is important for increasing the
beekeeping potential of an area. Without proper bee forage
management, it is difficult to maintain an apiary of strong
and healthy bee colonies. Poor management of bee forage,
especially during dearth periods, results in weak colonies
which are susceptible to various diseases and infections. Bee
forage potential and therefore, beekeeping carrying capacity
can be increased by establishing beekeeping oriented
plantations. Managing honey plant resources is necessary for
improving the beekeeping potential of an area .
Attention is not given to maintain the existing bee flora
and multiplication of multipurpose plant species in order to
make beekeeping sustainable. Inadequate information on bee
forage resources are a major obstacle to improve the
161 Tura Bareke et al.: Screening of Potential Shrubs for Bee Forage Development
production and productivity of honeybees in mixed crop
farming of Ethiopia. It is also important to screen suitable
bee forage species that have compatibility with existing
farming systems, high nutritive value, fast growth, easy to
manage and resistance to diseases and pests .
Bee forage trees/shrubs provide bees with ample of food
source (nectar and pollen) due to their relatively large canopy
spread, and long flowering duration. Bee forage shrubs/trees
not only provide nectar and pollen for the honeybees but also
used as food, ornamental, shade tree and live fence for the
beekeepers . Hence, to gain optimum benefit from
honeybee forage shrubs screening and adapting of the well
performing multipurpose species is essential to increase
honey production. Therefore, the objective of the study was
to evaluate and screen well performing shrubs bee plants and
recommend best performing for the users.
Description of Study Areas
The study was carried-out at Holeta Bee Research Center.
The site is located at an elevation of 2400 m.a.s.l, at
09°03.5’N latitude and 038° 30.367’E longitudes. The
predominant soil type in the study area is red soil.
Candidate Bee Forage Plant Selection
Potential shrubs were identified through interview of
farmers, observation of foraging bees on each flower of
candidate shrubs during different flowering seasons
(Sep/Oct, Dec/ Jan, April/May and Jun/July) and literature
review. Accordingly 5 shrub bee forages were put under
investigation (table 1)
Table 1. Identified candidate bee forage and their range of distribution.
No Botanical name Common name Growing Agroecological zone
1 Vernonia amygdalina Eebicha(Or), Girawa(Am) 500-2800 m.a.s.l.
2 Buddleja polystachya Anfara(Or) 1000-3300 m.a.s.l.
3 Callistemon citrinus Bottle brush (Eng) 1250-2500 m.a.s.l.
4 Dovyalis caffra Koshim (Amh) 1500-2600 m.a.s.l.
5 Chamecytisus proliferus Tagasaste up to 3200 m.a.s.l.
Matured seeds of Vernonia amygdalina, Buddleja
polystachya, Callistemon citrinus, Dovyalis caffra and
Chamecytisus proliferus were collected from respective
mature plant species. Immediately after collection, seeds
were packed and allowed to dry for one and half week at
room temperature. The packages were maintained at room
temperature until day of sowing.
Nursery Establishment and Experimental Setup
Seed was sown and seedlings of the species were raised in
nursery bed. The seedlings were transplanted to plots size
4mx5m, with 0.5 m spacing between plants and 1m between
rows. Completely randomized block design was used with
three replications. All necessary data such as, flowering date,
number of flowers heads per plant, pollen grain and foraging
intensity of honeybees were recorded on a note book until the
end of data collection. At 50% flowering, number of flower
heads/plant was counted randomly from three plants.
Foraging bee intensity on flowers was counted starting from
6: 00 a.m. to 6: 00 p.m. for ten minutes at every 2 hour
interval. Finally, the collected data were statistically analyzed
using descriptive statistics and ANOVA.
Time required giving flower: The mean time required to
give flower was significantly different at (p<0.05) among the
bloomed species. V. amygdalina has shorter time to give
flower compared to C. proliferus and C. citrinus (Table 2).
However, under similar condition B. polystachya and D.
caffra did not flower until the end of five years of the study
Average number of flower heads per plant: Average
number of flower heads per plant was highest for C.
proliferus as compared to C. citrinus and V. amygdalina and
it was significantly different (p<0.05) from the rest (Table 2).
Pollen yield: the mean amount of pollen yield of C.
Citrinus was significantly the lowest at (p<0.05) compared to
C. proliferus and V. amygdalina which has similar pollen
yield (Table 2).
Time from blooming to shedding: The mean flowering
length of C. citrinus was the highest which stayed up to six
months with a lot of flowers and some flower throughout the
year. Whereas, C. proliferus and V. amygdalina stayed almost
for three and two months, respectively. Statistically they were
significantly different (p<0.05) from each other (Table 2).
Table 2. Mean number of flower heads per plants (MNFHP), Mean time to give flower (MTGF), Pollen yield (PY) and Time from blooming to shedding
(TBSH) ± Standard Deviation (SD) of Chamecytisus proliferus, Callistemon citrinus and Vernonia amygdalina.
Plant species MNFHP ± SD MTGF ± SD PY ± SD TBSH ± SD
Chamecytisus proliferus 1247.8 ± 349.1a 3.00 ± 0.2b 0.14 ± 0.05a 80.9 ± 3.8b
Callistemon citrinus 151.2 ± 31.0 b 3.29 ± 0.4a 0.09 ± 0.03b 189.1 ± 6.2a
Vernonia amygdalina 72.6 ± 9.2 c 2.53 ± 0.3c 0.13 ± 0.03a 55.4 ± 2.6c
Different letters shows significant difference
Journal of Plant Sciences 2017; 5(5): 160-164 162
Figure 1. Performance of planted plants.
Foraging Intensity of Bees
Vernonia amygdalina was highly visited by bees from
10am-12 am followed by Callistemon citrinus. Almost at
6am and 6pm the number of bees visited the plant species
were null. C. proliferus has long peak foraging time in a day
than V. amygdalina and C. citrinus. Because C. proliferus
flowered during rainy season and cold weather condition
Figure 2. Foraging intensity of bees on the three different plant species.
163 Tura Bareke et al.: Screening of Potential Shrubs for Bee Forage Development
A number of flower heads per plant were the highest for
Chamecytisus proliferus. This is due to their growing habit
and crown size. Plant with more branching produces more
flower heads per plant .  also revealed that plants with
more vegetative growth produce more flowers. Bee forage
plants which take a long time from blooming to shedding are
very important for honey production whereas those have
short flower shedding time is used for bee colony buildup.
The foraging time of honeybees has varied from bee
forage plant species to species, and the peak foraging time
ranged from 12 p.m-2p.m. The observations recorded on the
foraging intensity of the honeybees showed that visiting bees
were few in the early morning and late in the evening due the
cold weather condition. V. amygdalina and C. citrinus was
highly foraged by bees 10:00am-12:00 am, while C.
proliferus from 10:00 am -2:00pm. The foraging time of
honeybee is varying from plant species to species based on
nectar secretion time and pollen potentiality of plants. V.
amygdalina is flowered from December-February in the area
depending on the rainfall, and honeybees collect pollen and
nectar from the flowers frequently. In these months
herbaceous bee forage plants dried and there is only a few
bee forage plant species in flower around the area . C.
proliferus flowered from June to August in the area. This is
the summer season in the area, in which the high rainfall
dropped. This time is also considered as dearth period in
view of beekeeping because only a few bee forage plant
species in flower, the weather condition is very cold and
difficult for honeybees to get food in the area. Callistemon
citrinus flowered throughout the year. It flowered mostly
during the dry season, some trees but may be found with
flowers any time of the year under good rain conditions. It
starts blooming from the branches close to the stems and
goes to the end of the branches. When the first bloomed
flower gives seeds and the flower at the end of branches have
flowered and vice versa. Callistemon citrinus is used and
cultivated for ornamental purposes it is to some extent salt
tolerant and can grow on very poor dry soils. Callistemon
citrinus provides sufficient quantities of nectar and pollen for
honeybees. Therefore, it assists indirectly with honey
production by stimulating brood rearing and strengthening
bee colonies, particularly when other plants are not flowering
and the flowered plant species have no diversity in the area
Foraging is essential to a honeybee colony’s survival. To
forage successfully, a bee has to learn and remember not only
the color and shape of the flowers that contain nectar and
pollen, but also how to get to them [5, 13]. Honeybees are
able to remember the period of the day when the resources
are higher . They can quickly identify unrewarding
patches and might leave them if the amount of resources
gained does not compensate for the energy spent collecting it
. The variation of number of bee count is associated with
different factors such as attractiveness of the flower, number
of flower heads per plants, nectar and pollen yield of plants
and weather condition . This is also in agreement with
 the intensity of bee visit is measure of potentiality of
plants for nectar and pollen production. Generally, from
beekeeping point of view it is economical to select plant
species with high bee foraging intensity (showed the quality of
pollen and or nectar), more flower heads, and longer flowering
period which provides continuous food source for the
honeybee colonies .
In conclusion this study revealed that all plant species
included in the study showed good vegetation growth
performances. However, C. citrinus, C. proliferus and V.
amygdalina were given flower with the ranges of 2-3.5
years while B. polystachya, and D. caffra are not flowered up
to the end of five years. All bee forages plants bloomed were
visited by honeybees well. Because the flowering time of C.
citrinus, C. proliferus and V. amygdalina are almost during
the dearth period and only a few bee forage plant species in
flower around the area. They provide a good amount of
nectar and pollen for honeybees. The time spent by bees for
foraging on the flowers depends on the amount of nectar and
pollen present in the flower. The peak foraging time is
associated with nectar and pollen potentiality and floral
preference of honeybees. Even though C. citrinus, C.
proliferus and V. amygdalina selected as major bee forages
plants in this trial, however, it requires further evaluation
particularly on nectar volume and sugar concentration for
these plants and their integration with watershed
development is recommended because they are fast growth
Since C. citrinus, C. proliferus and V. amygdalina were
flowered in dearth period and their planting is recommended
to increase honey production.
The authors are thankful to Holeta Bee Research Center
and Oromia Agricultural Research Institute for providing
required facilities and logistics. Our sincere thanks are also to
Konjit Asfaw and Tesfaye Abera, for their inspiration and
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