Abstract
The availability of bee forage limits honeybee productivity and is very important for beekeepers. Therefore, the current study aimed to identify the major botanical resources of honeybee, A. mellifera scutellata, in Southwest Ethiopia. Between October 2019 and October 2020, 69 group discussions (8–12 beekeepers), field observations, and pollen analysis were used to collect data. A total of 72 honey samples were collected from five districts at different seasons for pollen analysis. Most of the honey samples tested (93.06%) were multifloral, while 6.94% were monofloral. Melissopalynological analysis indicated that Eucalyptus camaldulensis (52.02%) was the predominant pollen type and is considered monofloral honey. Terminalia spp. (25.96%), Guizotia spp. (17.80%), and Bidens spp. (17.61%) were secondary pollen types and classified as multifloral honey. Terminalia spp., Guizotia spp., Vernonia spp., Bidens ssp., Plantago spp., and E. camaldulensis were pollen types recorded in honey samples in all agroecologies. Beekeepers ranked Schefflera abyssinica, Vernonia amygdalina, and Cordia africana as the first source of pollen and nectar for honeybees in highland, midland, and lowland, respectively. Additionally, V. amygdalina, Coffea arabica, Croton macrostachyus, and C. africana were commonly observed bee flora in all agroecologies. Honey bee management, such as bee forage shortages, the occurrence of brood and swarming, varied significantly (P < 0.05) among different agroecologies. In the present study, 53 honeybee plants were identified as pollen and nectar sources for honeybees. Various herbs (41.50%), trees (30.20%), and shrubs (28.30%) played a major role in honey production. Thus, beekeeping should be integrated with vegetation conservation for livelihood improvement and food security. Furthermore, existing bee flora should be cultivated in areas to increase the harvesting of honeybee products and improve the apiculture industry.
Keywords: Botanical origin, Monoflora, Multiflora, Eucalyptus camaldulensis, Pollen type
1. Introduction
The honeybee flora is the most important factor that influences the behavior or actions of honeybees and the quality of honey [1,2]. Pollen provides protein, vitamins, fatty acids and other nutrients for honeybees, whereas nectar provides carbohydrates [1,3]. Adequate nectar and pollen resources are very important to maintain the health of honeybees. However, a shortage of both quantity and quality of pollen and nectar can lead to a decrease in the number of colonies that collect them [2,4]. The limited availability of floral resources for honeybees can affect their production and productivity, which is crucial for beekeepers [[5], [6]]. Thus, honey pollen analysis helps to understand the distribution and abundance of foraging sources in the region, which allows assessing the potential of the area for honey production at the commercial level [7].
Ethiopia has a diverse agro-ecological and climatic conditions that are suitable for beekeeping [8]. The flowering plants known in Ethiopia are composed of six to seven thousand species spread across diverse agroecological zones [9]. This makes the country highly suitable for bees and beekeeping [10]. However, these variations in topography and the different climate zones complicate the development of flowering calendars in the country [8]. Therefore, the identification of nectar and pollen source plants is essential for the development of beekeeping. A calendar that displays the blooming sequence of different plants in a particular region serves the purpose of identifying the primary flowering periods and periods of scarcity. This information can be used to cultivate appropriate plants that can fill in the gaps during non flowering periods [11,12].
Melissopalynology is the analysis of pollen grains present in honey [7,13], which is important to determine the geographical and botanical origin of honey through a microscopic examination of honey sediments [14,15]. Every plant species has its genetic code of inheritance and a specific structural pattern that enable the pollen grain of one species to be differentiated from another [16,17]. Furthermore, the melissopalynological analysis of honey is more accurate than a visual survey for the study of honeybee forage, which is the most important tool for the development of regional apiculture [18]. It also provides information about the pollen and nectar sources used by honeybees in the region for honey production [19]. Honey can be monofloral or multifloral. Monofloral honey is a type of honey made predominantly from the pollen of a single plant species, whereas multifloral honey contains pollen from different plant species [13,17].
The identification of bee forage and their flowering period is important for beekeeping in Ethiopia to enhance honey production [20]. Therefore, it is essential to assess different agroecology to determine the availability of bee forage and establish a flowering period of honey plants that allows effective seasonal colony management. Agroecology can influence bee forage sources, temperature, and humidity in the study areas. Thus, the agroecology of a particular location may affect the availability, duration of flowering, flowering phenology, nectar production, and pollen production of various bee plants. This in turn has an impact on the production and seasonal growth of bee colonies [12,21]. The study areas are characterized by varied agroecologies that range from low to highlands and have diversified type of vegetation and various types of cultivated crops. Therefore, this study was carried out to determine the floral source of honey and identify the main bee forages that contribute to honey production in southwest Ethiopia for effective honeybee management.
2. Materials and methods
2.1. Study areas
The study was carried out in six selected districts of the Sheka, Bench-Sheko, and Majagn zones in southwest Ethiopia, namely Anderacha, Yeki, Guraferda, Sheko, Godare, and Megesh districts (Fig. 1a) for two consecutive years from October 2019 to October 2020. The agroecological zones of the study areas were classified into three categories, namely lowland (1500 m.a.s.l.), mid-altitude (1500–2300 m.a.s.l.) and highland (>2300 m.a.s.l.). The selected districts were classified as highland (Anderach, Sheko), midland (Yeki), and lowland (Guraferda, Godare and Mengesh) agroecological zones. The Bench-Sheko and Sheko zones are located southwest of Addis Ababa, the capital of Ethiopia, at 561 km and 694 km, respectively. Majagn is one of the Gambella Region administrative zones and borders southeast by the Southwest Region . The Majang zone is 628 km from Ethiopia's capital, Addis Ababa. The zone is characterized by the production of forest coffee along with the spices that are collected from the forests for the market. The altitude, annual rainfall ranges, and average annual temperature of the selected zones are summarized in Table 1. The landscape structure of the study sites is shown in Fig. 1b. A total of three sites and 18 honey samples were taken from highland and midland, respectively. A total of 36 honey samples were collected from lowland areas at six different sites. Farmers in the Bench-Sheko, Sheka, and Majagn zones earn their livelihoods by the mixed crop-livestock production system and beekeeping.
Fig. 1.
Map showing the study areas (A) Map showing landscape structures of the study sites (B).
Table 1.
Annul temperature, rainfall range and altitude of selected zones in southwest Ethiopia.
| Zones | Temperature (°C) | Rainfall range (mm) | Altitude (m.a.s.l.) |
|---|---|---|---|
| Bench-Sheko | 20–40 | 1200–2000 | 850–3000 |
| Sheka | 15.1–27.5 | 1201–1800 | 1200–3000 |
| Majagn | 17.6–27.5 | 1401–1800 | 562–2444 |
m.a.s.l.: meters above seas level.
2.2. Site selection and honey sample collection
In this study, the Bench-Sheko, Sheka and Majagn zones were selected purposively based on the potential of beekeeping practices. Five districts were randomly selected, namely Yeki, Guraferda, Sheko, Godare, and Megeshi. Volunteer beekeepers who managed honey colonies in apiaries were selected through the districts' apiculture departments in Guraferda (Kuja, Sega, and Chodit), Sheko (Gotika, Sheita, and Shimi), Yeki (Tepi Agricultural Research Center (TARC) at the station, Beko and Addis Berhan), Godare (Meti 02 and Mehal Meti) and Megeshi (Dush) as indicated in Fig. 1b. Then, a total of 12 sites were selected and honey bee colonies were established for honey samples. A total of 24 colonies of Apis mellifera scutellata honeybees were placed in Langstroth-type hives in the selected district of study zones. For each site, two colonies of honeybees were established for honey harvesting for melissopalynological analysis [22]. Fresh honey samples were collected from various districts, including Yeki, Guraferda, Sheko, Godare, and Mengesh, during both the major and minor harvest seasons, for laboratory analysis. A total of 72 honey samples were collected from the selected districts of the Sheka (18), Bench-Sheko (36), and Majagn (18) zones. These samples were taken using a simple random sampling method at the end of November, February, and April. The honey samples were stored at room temperature (25–30 °C) and then transported to the Holeta Bee Research Center for pollen analysis.
2.3. Melissopalynological analysis
Honey pollen analysis was carried out following the procedure adopted by Ref. [13] and [23] for the determination of the botanical composition and frequency of pollen types in honey. Approximately 10 g of each honey sample was mixed with 20 ml of warm water (40 °C). The solution was centrifuged at 2500 rpm for 10 min. The supernatant liquid was carefully sucked and decanted in a graduated centrifuge tube of the right size, to recover all the sediment. It is then centrifuged again for 10 min and the sediment volume reads in the graduated tube. After taking the complete suspension, it was available for use in the acetolysis method [24]. The sediment was mounted on slides in glycerin jelly (stained with safranine) and sealed with paraffin wax. The pollen grains thus prepared from each were examined under a light microscope with a 40× and 100× objective lens. Identification was done with the help of reference slides prepared from local flora, as well as published accounts [25]. The pollen grains obtained from the honey samples were identified and compared with the reference slides made from the identified plants. Pollen spectra were constructed on the basis of their percentages and hence the honey types of the area were determined. Pollen was categorized as predominant pollen (>45%), secondary pollen (16–45%), minor important minor pollen (3–15%) and minor pollen (<3%) according to Ref. [13].
2.4. Sampling techniques and sample size determination
Focus group discussions, key informant interviews, and personal observation were used to collect data on bee forage. Multistage purposive random sampling method was used to select Sheka, Bench-Sheko and Majegn zones based on the beekeeping potential. Six districts were randomly selected from the selected zone, namely Anderach, Yeki, Sheko, Guraferda, Godare and Mengesh. A total of 28 kebeles were randomly selected from these districts. Two focus group discussions were held in each kebele . The key informants were all beekeepers from different kebeles. A total of 69 focus groups with 8–12 beekeepers in each group were used in the discussion. Beekeepers were also asked to rank honeybee forage according to the importance and abundance of plants. In each district, five key informants were interviewed regarding the major bee flora with their flowering time, abundance, importance, seasonal forage availability and habits. Additionally, focus groups and key informant interviews were used to record data on honey harvesting seasons and honeybee management (Appendix A).
The absence of a colony is characterized as the whole colony abandoning the nest. In contrast to swarming, the entire colony leaves and likely searches for and locates a new nest location elsewhere, rather than the nest dividing into two or more parts. The process by which honeybee colonies reproduce and generate new colonies is known as natural swarming. It is the process by which the honey bee increases its chances of survival as a species [26]. Migration, on the other hand, refers to the movement of a honeybee colony across various biological zones [27]. The shortage of bee forage in this study is defined as the time when there is a shortage of plant flora in the areas. Colony dynamics determine whether the local honeybee population is growing or decreasing. The presence of male honey bees in the colony indicates the availability of drones. Seasonal management of honey bee colonies includes manipulating the hive and hive space to provide room for the expanding brood-rearing area and the storage of surplus honey as needed. Poisonous plants are those that kill or paralyze honeybees when they come into contact with or ingest nectar or pollen from them [28].
2.5. Data analysis
All the collected data were analyzed using descriptive statistics and other related tools using SPSS software. The data were presented in frequency, table, and figure. The association between honeybee management and agro-ecology was tested using the χ2-test. For all statistical analysis, 95% CI and a critical value of 0.05 was used.
3. Results and discussion
3.1. Melissopalynological analysis of honey
A total of 31 pollen types and 22 plant families were identified in 72 honey samples using melissopalynological analysis (Table 3, Fig. 2, Fig. 3). Of all the honey samples that were tested, the majority (93.06%) were found to be multifloral, while the remaining 6.94% were monofloral (Table 2).The melissopalynological analysis of honey is crucial to determine both its geographical and botanical origin [15]. This method provides more accurate results compared to visual surveys, making it an essential tool for studying honeybee forage and the development of regional apiculture [18]. Terminalia species (Combretaceae) and Guizotia species (Asteraceae) were the type of secondary pollen observed in all agroecology honey, while Eucalyptus camaldulensis (Myrtaceae) was the type of secondary pollen in highland and midland agroecology honey. Bidens species were also secondary pollen types in lowland honey (Table 3 ). The diversity of important minor and minor honey source plant species was higher than the predominant and secondary pollen types.
Table 3.
Honey pollen analysis categories of honey source plants in southwest Ethiopia.
| Plant family | Pollen type | Honey sample/frequency classes (%) |
||||
|---|---|---|---|---|---|---|
| Guraferda | Sheko | Yeki | Godare | Mengesh | ||
| Combretaceae | Terminalia spp | 25.96 | 17.98 | 35.24 | 7.11 | 6.89 |
| Mimosaceae | Acacia spp | 2.39 | ||||
| Asteraceae | Bidens spp | 2.49 | 5.33 | 17.61 | 15.25 | 14.45 |
| Guizotia spp | 17.80 | 16.04 | 17.01 | 6.61 | 7.03 | |
| Vernonia spp | 3.80 | 3.86 | 5.65 | 0.31 | 0.25 | |
| Myrtaceae | Eucalyptus camaldulensis | 6.25 | 16.58 | 19.65 | 52.02 | 48.36 |
| Syzygium spp | 0.68 | 0.58 | 2.42 | 3.06 | ||
| Plantaginaceae | Plantago spp | 4.82 | 5.30 | 0.88 | 1.56 | 0.89 |
| Primulaceae | Maesa lanceolata | 7.94 | 9.96 | 1.89 | ||
| Poaceae | Zea mays | 0.03 | 0.03 | |||
| Rosaceae | Pygeum africanum | 7.88 | 8.99 | |||
| Rubus steudneri | 0.15 | 0.21 | ||||
| Acanthaceae | Justicia schimperiana | 0.51 | 5.09 | 0.15 | ||
| Hypoe stestrifolia | 0.06 | 0.31 | 0.45 | |||
| Ebenaceae | Euclea keniensis | 0.65 | 0.63 | |||
| Lamiaceace | Ocimume bacilium | 0.74 | 1.00 | |||
| Plectranthus spp | 0.68 | 0.21 | ||||
| Ceanothusafricanus | 0.43 | 0.72 | ||||
| Liliaceae | Olea spp | 0.09 | ||||
| Rutaceae | Clausena anisata | 10.21 | 0.21 | |||
| Cannabaceae | Celtis kraussiana | 6.80 | ||||
| Brassicaceae | Lepidium sativum | 0.17 | 1.02 | 0.03 | ||
| Boraginaceae | Trichodesma spp | 0.11 | 0.69 | |||
| Cleomaceae | Cleome spp | 7.26 | ||||
| Hypericaceae | Hypericm qurtinianm | 0.02 | ||||
| Dombeya aethiopia | 0.18 | 0.12 | ||||
| Malvaceae | Pavonia schimperiana | 0.26 | ||||
| Solaneceae | Datura spp | 0.29 | 0.21 | 0.49 | 0.38 | |
| Euphorbiaceae | Croton spp | 0.06 | 0.69 | 0.54 | ||
| Acalypha indica | 12.24 | 9.56 | ||||
| Ericaceae | Erica arborea | 0.25 | 0.23 | 0.43 | ||
Frequency classes: predominant pollen (>45%), secondary pollen (16–45%), important minor pollen (3–15%), minor pollen (<3%).
Fig. 2.
Percentage of pollen grains of plant families for the honey of Apis mellifera scutellata from different plant sources in southwest Ethiopia.
Fig. 3.
Pollen grain shapes of some plant species mention in the study (1) Eucalyptus camaldulensis (2) Plantago spp. (3) Zea mays (4) Terminalia spp. (5) Acacia spp. (6) Guizotia spp. (7) Croton spp. (8) Coffee arabica (9) Syzgium spp. (10) Vernonia spp. (11) Bidens spp, (12) Hypoes testrifolia (13) Euclea keniensis (14) Ocimume bacilium (15) Justicia schimperiana.
Table 2.
Number of pollen by origin area and honey type in study area.
| Site | District | Total number of pollen per slide | Classification of honey |
|---|---|---|---|
| Kuja1 (K1) | Guraferda | 211 (12.79) | Multifloral |
| Kuja2 (K2) | Guraferda | 8289 (50.25) | Monofloral |
| Kuja3 (K3) | Guraferda | 220 (1.33) | Multifloral |
| Kuja4 (K4) | Guraferda | 570 (3.46) | Multifloral |
| Kuja5 (K5) | Guraferda | 551 (3.34) | Multifloral |
| Kuja6 (K6) | Guraferda | 660 (4.00) | Multifloral |
| Sega1 (S1) | Guraferda | 125 (0.75) | Multifloral |
| Sega2 (S2) | Guraferda | 857 (5.20) | Multifloral |
| Sega3 (S3) | Guraferda | 335 (2.03) | Multifloral |
| Sega4 (S4) | Guraferda | 1056 (6.40) | Multifloral |
| Sega5 (S5) | Guraferda | 263 (1.59) | Multifloral |
| Sega6 (S6) | Guraferda | 145 (0.88) | Multifloral |
| Chodit1 (CH1) | Guraferda | 665 (4.03) | Multifloral |
| Chodit2 (CH2) | Guraferda | 458 (2.78) | Multifloral |
| Chodit3 (CH3) | Guraferda | 600 (3.64) | Multifloral |
| Chodit4 (CH4) | Guraferda | 225 (1.36) | Multifloral |
| Chodit5 (CH5) | Guraferda | 605 (3.67) | Multifloral |
| Chodit6 (CH6) | Guraferda | 660 (4.00) | Multifloral |
| Gotika1(G1) | Sheko | 737 (5.61) | Multifloral |
| Gotika1(G2) | Sheko | 6307 (48.01) | Monofloral |
| Gotika1(G3) | Sheko | 881 (6.71) | Multifloral |
| Gotika1(G4) | Sheko | 742 (5.65) | Multifloral |
| Gotika1(G5) | Sheko | 537 (4.09) | Multifloral |
| Gotika1(G6) | Sheko | 2232(16.99) | Multifloral |
| Sheita1(SH1) | Sheko | 1250 (9.52) | Multifloral |
| Sheita1(SH2) | Sheko | 2501 (19.04) | Multifloral |
| Sheita1(SH3) | Sheko | 716 (5.45) | Multifloral |
| Sheita1(SH4) | Sheko | 1098 (8.36) | Multifloral |
| Sheita1(SH5) | Sheko | 339 (2.58) | Multifloral |
| Sheita1(SH6) | Sheko | 996 (7.58) | Multifloral |
| Shimi1 (SHI1) | Sheko | 116 (0.88) | Multifloral |
| Shimi1 (SHI2) | Sheko | 142 (1.08) | Multifloral |
| Shimi1 (SHI3) | Sheko | 3385 (25.77) | Multifloral |
| Shimi1 (SHI4) | Sheko | 118 (0.09) | Multifloral |
| Shimi1 (SHI5) | Sheko | 440 (3.35) | Multifloral |
| Shimi1 (SHI6) | Sheko | 600 (4.57) | Multifloral |
| TARC on station1 (TARC1) | Yeki | 6222 (49.33) | Monofloral |
| TARC on station2 (TARC2) | Yeki | 2354 (18.66) | Multifloral |
| TARC on station3 (TARC3) | Yeki | 677 (5.37) | Mutifloral |
| TARC on station4 (TARC4) | Yeki | 105 (0.83) | Multifloral |
| TARC on station5 (TARC5) | Yeki | 2110 (16.73) | Multifloral |
| TARC on station6 (TARC6) | Yeki | 202 (1.60) | Multifloral |
| Site | District | Total number of pollen per slide | Classification of honey |
|---|---|---|---|
| Beko1 (BE1) | Yeki | 120 (0.95) | Multifloral |
| Beko2 (BE2) | Yeki | 1038 (8.23) | Multifloral |
| Beko3 (BE3) | Yeki | 118 (0.94) | Multifloral |
| Beko4 (BE4) | Yeki | 225 (1.78) | Multifloral |
| Beko5 (BE5) | Yeki | 225 (1.78) | Multifloral |
| Beko6 (BE6) | Yeki | 108 (0.85) | Multifloral |
| Addis Berhan1 (AD1) | Yeki | 330 (2.62) | Multifloral |
| Addis Berhan2 (AD2) | Yeki | 225 (1.78) | Multifloral |
| Addis Berhan3 (AD3) | Yeki | 330 (2.62) | Multifloral |
| Addis Berhan4 (AD4) | Yeki | 225 (1.78) | Multifloral |
| Addis Berhan5 (AD5) | Yeki | 338 (2.68) | Multifloral |
| Addis Berhan6 (AD6) | Yeki | 660 (5.23) | Multifloral |
| Meti02-1 (M-02-1) | Godare | 465 (6.61) | Multifloral |
| Meti02-2 (M-02-2) | Godare | 997 (14.17) | Multifloral |
| Meti02-3 (M-02-3) | Godare | 432 (6.14) | Multifloral |
| Meti02-4 (M-02-4) | Godare | 3400 (48.32) | Monofloral |
| Meti02-5 (M-02-5) | Godare | 158 (2.25) | Multifloral |
| Meti02-6 (M-02-6) | Godare | 445 (6.32) | Multifloral |
| Mehal Meti 1 (MM1) | Godare | 220 (3.13) | Multifloral |
| Mehal Meti 2 (MM2) | Godare | 448 (6.37) | Multifloral |
| Mehal Meti 3 (MM3) | Godare | 332 (4.72) | Multifloral |
| Mehal Meti 4 (MM4) | Godare | 225 (3.20) | Multifloral |
| Mehal Meti 5 (MM5) | Godare | 114 (1.62) | Multifloral |
| Mehal Meti 6 (MM6) | Godare | 800 (11.37) | Multifloral |
| Dush1 (DU1) | Mengesh | 258 (4.15) | Multifloral |
| Dush2 (DU2) | Mengesh | 660 (10.62) | Multifloral |
| Dush3 (DU3) | Mengesh | 465 (7.49) | Multifloral |
| Dush4 (DU4) | Mengesh | 997 (16.05) | Multifloral |
| Dush5 (DU5) | Mengesh | 432 (6.95) | Multifloral |
| Dush6 (DU6) | Mengesh | 3400 (54.73) | Monofloral |
TARC: Tepi Agricultural Research Center.
This result showed that naturally occurring plants, eg, Terminalia spp., Acacia spp., Croton spp., and cultivated plants, eg Zea mays, Eucalyptus camaldulensis, and Bidens spp. were the floral source for honeybees. This is consistent with the findings of [29,30]; and [31]; who stated that honeybee foraging on multiple plant species from natural as well as agricultural ecosystems due to this different pollen spectrum was observed in honey. Terminalia spp., Guizotia spp., Vernonia spp., Bidens spp., Plantago spp. and E. camaldulensis were pollen types recorded in different agroecology (Table 3). Acacia spp., Olea spp., Hypericm qurtinianm, Pavonia schimperiana, Celtis kraussiana and Cleome spp. were the pollen types recorded in honey samples obtained in specific areas (Table 3). The occurrence of common and specific pollen types in honey samples can be attributed to the distribution and diversity of plants in a particular area depending on the agroecology of the area [32]. In the current study, pollen types that had no confirmed botanical affinity were called ‘undetermined'.
The type of pollen E. camaldulensis (Myrtaceae) in lowland honey was identified as the predominant pollen type, which was considered as monofloral honey (Table 2, Table 3). Monofloral honey is usually produced from one plant species [33] and pollen amounts to more than 45% of the total pollen content. This may be due to the floral constancy behavior of honeybees that help to stay in a single species of plant reward food and continue until the flower ends the production of nectar or pollen [15,34]. Reviews by Ref. [8] showed that E. camaldulensis is one of the most important honeybee forage plants that provided monofloral honey in Ethiopia. Similarly to this finding [35], found that E. camaldulensis was a significant source of honey plants in the Wando district that produced monofloral honey. The honey samples collected from the three agroecology areas had several pollen types with low density and were therefore classified as multiflora honey (Table 2, Table 3). This may be due to honeybees preferring specific flora based on the availability of flora in a specific region and bees less frequently visiting flowering plant species in a particular region [31,32]. Consistent with the findings of [32]; the present result identified that several honey samples had a mixture of secondary pollen, important minor pollen, or minor pollen and could be categorize as multiflora honey. The existence of pollen types of cultivated plants in honey samples like Zea mays (Mytaceae) indicates that agro-ecosystems provide floral sources of bees. This plant is important for the survival and production of honeybees, particularly when natural flowering plants are not blooming. Similar findings were observed in Kenya by Refs. [32,36]. Cultivated crops produced unique honey, therefore management of the agro-ecosystem in the areas can help the survival of honeybees and increase honey yield. Most of the honey bee plants identified by pollen analysis from honey samples were similar to those of beekeepers response to honey bee flora in the study areas.
Melissopalynology, which is the study of pollen grains present in honey to identify plant species visited by bees while foraging for nectar, is essential to assess the quality, origin, and potential medicinal properties of honey samples [37]. In the case of African honey, pollen grains can be used to identify floral sources that contribute to the unique taste and aroma of honey. African honeys are known to contain a high diversity of pollen types, including some peculiar African pollen that cannot be found anywhere in the world [38].
Several studies have documented the pollen spectra of different African regions, including Ethiopia. Consistent with this finding [39], conducted a study on the pollen spectra of honeys from various regions of Ethiopia. The study identified several pollen types commonly found in African regions, such as Eucalyptus, Acacia, and Brassica. Furthermore, various pollen images atlases, such as the “Pollen Atlas of the Tropics of Africa” by Ref. [40] in West Africa [41] in South Africa, and [42] in East Africa, are available to compare and identify different pollen types.
A recent study by Refs. [32,43] on the characterization of Nigerian and Kenyan honey, respectively, using melissopalynology included images of pollen grains in their report, which also supports the present study. These images provided visual aids for identifying the different types of pollen found in honey samples. It is crucial to authenticate honeys related to Ethiopia since honey adulteration is a common issue in the industry. Several studies have used melissopalynology to authenticate honey samples from different regions around the world [44,45]. Thus, discussing the results obtained in terms of the authenticity of Ethiopian honey can provide valuable information on the quality and purity of honey samples.
3.2. Honey harvesting seasons
A significant difference was observed in the honey harvesting seasons in the lowland, midland and highland agroecological zones. The majority (54.82%) of beekeepers harvested honey in May followed by April (41.89%) in the highlands (Fig. 4), while January (41.93%) and December (19.38%) were the minor honey flow months in the highlands (Fig. 5). February (33.33%) and January (26.71%) were the main honey flow months in lowland areas, with the minor honey flow in May (26.73%) as indicated in Figs. 3 and 4. Similarly, the major honey harvesting season was observed in January (44.81%) in midland areas, whereas a minor honey flow season was recorded in May (27.61%) in the spring season. This may be due to the fact that the distribution of natural vegetation and cultivated crops is different in agroecology. Additionally, the flowering season of the bee flora was different from place to place due to the diversity of plant habitats and environmental conditions [46]. Similarly to the present findings [47], reported that the honey harvesting seasons were different between different agroecology in the Sheka zone in the southwest part of the country. This finding also agrees with the previous study of [48] who reported that spring (April and May) is the major honey harvesting season and the end of autumn (November) and winter (January and February) is the minor harvesting season in selected zones of southwest Ethiopia. The current findings indicated that the honey harvesting cycle ranged from two to three times a year in southwest Ethiopia. This is in agreement with the previous findings [[49], [50], [51]], who observed that most beekeepers harvested honey 2–3 times a year in Ethiopia.
Fig. 4.
Major honey harvesting season in different agro-ecology in southwest Ethiopia.
Fig. 5.
Minor honey harvesting season in different agro-ecology in southwest Ethiopia.
3.3. Abundance of bee forage in different agroecology
The abundance and preference ranking of the bee flora for honey production was carried out through group discussion and key informant interviews. The abundance and priority uses of bee forage varied across agroecology; this may be due to the difference in vegetation type among various agroecology. In the current study, Schefflera abyssinica was the first plant prioritized for honey source in highland agroecology (Table 4). The abundance of S. abyssinica was attributed to its widespread distribution in the highlands of the southwest part of Ethiopia [17]. Consistent with the present result [46], indicated that S. abyssinica was a more frequent honey source in a highland area of the Jimma zone. Additionally, a previous study conducted in highland agroecology also indicated S. abyssinica as the main honey source [50]. Vernonia amygdalina, Coffea arabica, Croton macrostachys, and Cordia africana were flora of bees frequently observed in all agroecology (Table 4). These findings indicated that the bee flora was the source of nectar and pollen at different months and days. V. amygdalina was ranked first in the bee flora in the lowlands and second in the midlands and highlands in the present study (Table 4). This result also indicated that V. amygdalina had a wider distribution and was the most important source of nectar and pollen in all agroecology. This result agrees with the finding of [17]; who stated that V. amygdalina is the most abundant bee forage in midland agroecology. In the current study, C. africana was the first prioritized tree and most abundant bee forage in lowland agroecology. The quantity and quality of honey yield were affected by the types of bee forage available in the areas [52].
Table 4.
Abundance and priority in the importance of major honey bee forage species in southwest Ethiopia.
| Agro-ecology | Scientific name | Local name | Abundance | Rank |
|---|---|---|---|---|
| Highland | Schefflera abyssinica | Geteme | More abundant | 1 |
| Vernonia amygdalina | Grawa | Abundant | 2 | |
| Coffea arabica | Buna | Abundant | 3 | |
| Croton macrostachyus | Bisana | Abundant | 4 | |
| Persea americana | Avocado | Abundant | 5 | |
| Cordia africana | Wanza | Abundant | 6 | |
| Ficus sur | Shola | Medium | 7 | |
| Eucalyptus camaldulensis | Bahrzaf | Medium | 8 | |
| Opuntia ficus-indica | Qulkual | Medium | 9 | |
| Bidens macroptera | Adeyabeba | Abundant | 10 | |
| Midland | Vernonia amygdalina | Grawa | More abundant | 1 |
| Croton macrostachyus | Bsana | Abundant | 2 | |
| Schefflera abyssinica | Geteme | Abundant | 3 | |
| Zea mays | Bekolo | Abundant | 4 | |
| Cordia africana | Wanza | Abundant | 5 | |
| Mangifera indica | Mango | Abundant | 6 | |
| Carica papaya | Papaya | Medium | 7 | |
| Persea americana | Avocado | Medium | 8 | |
| Celosia argentea | Beklbelto | Abundant | 9 | |
| Coffea arabica | Buna | Abundant | 10 | |
| Lowland | Cordia africana | Wanza | More abundant | 1 |
| Vernonia amygdalina | Grawa | Abundant | 2 | |
| Combretaceae | Avalo | Abundant | 3 | |
| Albizia gummifera | Sesa | Abundant | 4 | |
| Croton macrostachyus | Bisana | Abundant | 5 | |
| Coffea arabica | Buna | Abundant | 6 | |
| Polyscias fulva | Yeznjerowenber | Abundant | 7 | |
| Bidens macroptera | Adeyabeba | Abundant | 8 | |
| Persea americana | Avocado | Abundant | 9 | |
| Ficu sur | Shola | Medium | 10 |
3.4. Honey bee management in different agroecologies
The highest shortage of bee forage was observed during August in highland (76.89%), while the highest shortage of bee forages was recorded in October in lowland (63.48%) with a significant difference (P < 0.05) (Table 5). Refs. [53,54] reported that the shortage of honeybee forage was one of the major constraints to the development of beekeeping, which is consistent with the findings of this study. Seasonal colony management showed a significant difference (P < 0.05) among different agroecology with maximum management required in January in all agroecology and since the highest brood developed during this month (Table 5).
Table 5.
Honey bee management in different agro-ecology in southwest Ethiopia.
| Variables | Categories | Study districts |
Chi-square (χ2) |
|||
|---|---|---|---|---|---|---|
| Highland (%) | Lowland (%) | Midland (%) | Value | P-value | ||
| Shortage of bee forage | August | 76.89 | 36.52 | 51.22 | 24.69 | 0.040 |
| October | 23.12 | 63.48 | 48.81 | |||
| Seasonal colony management | January | 57.61 | 66.73 | 90.00 | 7.84 | 0.020 |
| September | 42.41 | 33.33 | 10.00 | |||
| Major colony dynamic | Yes | 97.00 | 100.00 | 96.72 | 3.73 | 0.500 |
| No | 3.00 | 0,00 | 3.33 | |||
| Occurrence of brood | January | 72.13 | 73.14 | 87.00 | 36.44 | 0.010 |
| December | 15.24 | 15.42 | 6.54 | |||
| April | 12.11 | 11.48 | 6.48 | |||
| Colony migration | August | 57.48 | 69.68 | 10.33 | 28.53 | 0.200 |
| September | 15.16 | 4.33 | 6.91 | |||
| February | 15.22 | 4.31 | 13.84 | |||
| July | 12.13 | 21.74 | 69.00 | |||
| Natural swarming of the colony | January | 33.28 | 26.93 | 35.68 | 35.22 | 0.040 |
| December | 51.49 | 68.91 | 53.63 | |||
| February | 15.21 | 4.22 | 10.72 | |||
| Absconding of colony | September | 41.91 | 11.51 | 3.44 | 34.53 | 0.020 |
| July | 25.87 | 23.11 | 31.00 | |||
| August | 32.28 | 34.57 | 65.64 | |||
| Drone availability | April | 66.72 | 3.83 | 17.61 | 17.64 | 0.500 |
| January | 16.67 | 21.41 | 23.47 | |||
| December | 16.72 | 74.79 | 58.85 | |||
| Poisonous plant | Yes | 24.15 | 7.74 | 51.63 | 13.78 | 0.001 |
| No | 75.82 | 92.33 | 48.44 | |||
Natural swarming occurred in December in all agroecology with a significant difference (P < 0.05) among different agroecology (Table 5). Honeybees collected more pollen during the major flowering season, and the colony population increased with it [55]. Swarm cell usually occurs in very strong colonies and causes the honeybee colony to swarm. Moreover, large numbers of queens emerge during the major flowering season, and this causes honeybees to swarm [53]. These seasons provide an opportunity for the beekeeper to prepare their colony for colony multiplication purposes or to maximize their honey production.
The present study showed that a high absconding problem occurred in August in midland, resulting in significant differences (P < 0.05) among agroecology (Table 5). This may be due to a shortage of honeybee forage. Although swarming is a natural reproductive process in which a colony is split, absconding occurs when all bees leave the hive. Absconding is associated with low flowering plant density, and a shortage of honeybee forage causes honeybee colonies to abscond [56]. In agreement with this result, absconding could also be caused by drought, overgrazing, deforestation, honeybee disease, pest, predatory, water shortage, poor bee manipulation, and lack of protection against bad weather conditions [57].This supports previous findings [54] that absconding could occur in both traditional and improved hives and result in a significant financial loss. Therefore, beekeepers must provide supplement feed and prevent colonies from natural enemies and pesticides during the shortage period.
The poisonous plants of honeybees were significantly (P < 0.05) higher in midland agroecology than in other agroecology (Table 5). These plants are causes of death or paralysis of honeybees when they come in contact with or ingest nectar or pollen from poisonous plants, and also honey produced from these plants is toxic to humans [28,6]. This may be due to the insecticidal property of these plants [58]. According to Refs. [46,48], Euphorbia cotinifolia and Azadirachta indica are poisonous plants for honeybees in southwest Ethiopia. This result also agrees with [59] who reported that these plants are poisonous to honeybees, and also honey produced from those plants could affect human health. In contrast to this finding [60], indicated that Euphorbia cotinifolia was nontoxic to honeybees. This difference may be due to variations in agroecology, the genotype of plants, stage, and parts of plants.
Results of the present study contribute to the beekeeper to manage their colonies by installing hives, re-queen colonies, harvesting honey, and honey bee products. The dearth period was long and short based on agroecology and knowledge of bee flora helping the beekeeper's effective management of bee colony [61]. The peak of the honey harvesting season varies depending on colony management practices, agroecology, and the flowering condition of honeybee flora [62].
3.5. Honey bee flora
Most of the bee forages identified in the study areas were dominated by herb (41.50%) followed by trees (30.20%) and shrubs (28.30%). According to the findings of [35]; herbaceous plants predominated as honeybee forage in the west Arsi and east Shewa zones. Similar findings were reported by Ref. [11] , who identified that Schefflera abyssinica, Acacia spp., and Croton macrostachyus were the three pollen types that honeybee foragers most favored. Beekeepers also reported that the flowering month and flowering period depend on the activity of honeybees related to the frequency, time of visits and duration of foraging for a single type of honeybee plant (Table 6, Appendix A). Knowledge about the identification of bee flora helps beekeepers to recognize the honey harvesting season and the management of beehives [63].
Table 6.
Honeybee flora and their flowering month, period of flowering, and habit of plants in southwest Ethiopia.
| Scientific name | Vernacular name | Flowering month | Flowering period (days) | Habit |
|---|---|---|---|---|
| Agave sisalana | Kacha | January | Thirty | Shrub |
| Mangifera indica | Mango | January | Twenty | Tree |
| Capsicum annuum | Berberea | January | Fifteen | Herb |
| Aningeria altissima | Qerero | January | Thirty | Tree |
| Rumex nervosus | Imbuacho | January | Thirty | Shrub |
| Nicandra physalodes | Atefaris | January | Thirty | Herb |
| Vernonia amygdalina | Grawa | January to February | Twenty | Shrub |
| Isodon schimperi | Yefyel gomen | February | Twenty | Shrub |
| Hydrophila auriculata | Amekiela | February | Twenty | Herb |
| Coffea arabica | Buna | March | Fifteen | Shrub |
| Schefflera abyssinica | Geteme | April | Thirty | Tree |
| Albizia gummifera | Sesa | April | Thirty | Tree |
| Catha edulis | Chat | April | Fifteen | Shrub |
| Ocimum lamiifolium | Damakesi | April | Fifteen | Herb |
| Phylolacca dodecandra | Endod | April | Twenty | Shrub |
| Rumex nepalensis | Tult | April | Thirty | Herb |
| Polyscias fulva | Yezinjero wenber | April | Twenty | Tree |
| Croton macrostachys | Bisana | May | Twenty | Tree |
| Eucalyptus camaldulensis | Bahirzaf | May | Thirty | Tree |
| Coriandrum sativem | Dimblal | May | Fifteen | Herb |
| Zantedeschia aethiopica | Yeturubaabeba | May | Twenty | Herb |
| Celosia argentea | Beklbelto | May | Fifteen | Herb |
| Carica papaya | Papaye | June | Fifteen | Shrub |
| Medicago polymorpha | Wajima | June | Fifteen | Herb |
| Cordia africana | Wanza | September | Twenty | Tree |
| Acanthaus sennii | Koshashila | September | Twenty | Herb |
| Lycopersicon esuculentum | Timatim | September | Twenty | Herb |
| Physalis peruviana | Aetii | September | Thirty | Herb |
| Schimus molle | Birbira | September | Thirty | Tree |
| Ficus sur | Shola | September | Thirty | Tree |
| Scientific name | Vernacular name | Flowering month | Flowering period (days) | Habit |
|---|---|---|---|---|
| Psidium guajava | Zeytuna | September | Twenty | Tree |
| Achyranthes aspera | Telej | September | Thirty | Herb |
| Rumex nepalensis | Tult | September | Thirty | Herb |
| Persea americana | Avocado | October | Fifteen | Tree |
| Polygala steudneri | Antid | October | Fifteen | Herb |
| Phoenix reclinata | Zembaba | October | Thirty | Tree |
| Ficus vasta | Warka | October | Twenty | Tree |
| Citrus aurantifolia | Lomi | October | Thirty | Tree |
| Dombeya torrida | Wulkfa | October | Thirty | Tree |
| Guizotia abyssinica | Nug | October | Fifteen | Herb |
| Kalanchoe densiflora | Endahulla | October | Thirty | Herb |
| Bidens macroptera | Adeyabeba | November | Twenty | Herbs |
| Ricinus communis | Gulo | November | Twenty | Shrub |
| Cucurbita pepo | Duba | November | Fifteen | Herb |
| Zea mays | Bekolo | November | Ten | Herb |
| Polyscias fulva | Yezinjerowenber | November | Twenty | Tree |
| Sorghum bicolor | Mashila | December | Fifteen | Herb |
| Combretaceae | Avalo | December | Twenty | Shrub |
| Brassica carinata | Gomen | December | Fifteen | Herb |
| Opuntia ficus-indica | Qulqual | December | Fifteen | Shrub |
| Musa x paradisiaca | Muzi | December | Twenty | Shrub |
| Maesa lanceolata | Kelewa | December | Twenty | Shrub |
| Detura arborea | Turubaabeba | December | Thirty | Shrub |
| Justitia schimperana | Sensel | December | Thirty | Shrub |
3.6. Limitations of the study
The study focused only on the main plants used by honeybees and did not examine other factors such as climate, disease, and beekeeping techniques. Additionally, it did not analyze the effects of pesticides or changes in land use on bee feed and honey production. Despite these limitations, the study provided valuable information on the primary plant resources of honeybees in the study area, highlighting the need to combine beekeeping with vegetation conservation to improve livelihoods and food security. However, more research is necessary to overcome these limitations and gain a more comprehensive understanding of the availability of bee feed in Ethiopia. Future studies could utilize molecular methods to identify and quantify the diversity and nectar composition of the plants used by honeybees in the area.
4. Conclusions
The present study provides basic information about the sources of honeybee flora in the study areas. The study showed that Terminalia spp, Guizotia spp, and Bidens spp. were the secondary important pollen sources in the areas. However, E. camadulensis was identified as the predominant pollen type in the study areas. Terminalia spp, Guizotia spp, Vernonia spp, Bidens spp, Plantago spp, and E. scamaldulensis were pollen types recorded in honey samples in all agroecologies. Bee forage shortages, the appearance of brood, swarming, absconding, poisonous plant, and seasonal management were significantly varied between different agroecology. Therefore, beekeeping should be integrated with the conservation of honeybee floral resources and the plantation of fast-growing honeybee plants around apiaries. Furthermore, existing bee flora should be cultivated in areas to increase the harvesting of honeybee products and improve the apiculture industry.
Author contribution statement
Dereje Tulu; Melkam Aleme; Gezahegn Mengistu; Ararsa Bogale: Conceived and designed the experiments; Performed the experiments; Analyzed and interpreted the data; Contributed reagents, materials, analysis tools or data; Wrote the paper.
Amsalu Bezabeh; Esayas Mendesil: Conceived and designed the experiments; Analyzed and interpreted the data; Wrote the paper.
Data availability statement
Data will be made available on request.
Additional information
Supplementary content related to this article has been published online at [URL].
Declaration of competing interest
The authors declare no conflict of interest.
Acknowledgments
The authors would like to thank the Ethiopian Institute of Agricultural Research. Likewise, the authors are grateful to the, Sheka, Bench-Sheko and Majagn zone offices for their kind help and facilitation during the fieldwork.
Footnotes
Supplementary data to this article can be found online at https://doi.org/10.1016/j.heliyon.2023.e16047.
Appendix A. Supplementary data
The following are the Supplementary data to this article:
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Data Availability Statement
Data will be made available on request.