Honey bees of Ethiopia : their lineages and subspecies based on morphometrics, mitochondrial DNA, and mandibular gland pheromone analyses
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Public Library of Science
Abstract
Apiculture is a vital economic sector in Ethiopia, providing income and employment for over two million people. However, the classification of the honey bee subspecies in Ethiopia remains debatable. To shed light on this, we analysed wing geometric and classical morphometrics, mandibular gland pheromones, and COI–COII mitochondrial DNA sequences from worker honey bees collected across high, mid and low elevation gradients within Oromia, Amhara, and Southern Nations Nationalities and Peoples’ (SNNP) regions. Our results revealed significant regional morphological and pheromonal variation driven by elevation. Wing size increased with altitude, suggesting adaptive responses to elevation. Classical morphometrics supported this trend, with bees at higher elevation exhibiting larger flight structures. Regional differences in mandibular gland pheromone secretion were also observed, with workers from Amhara secreting the least quantities of these compounds, including the queen substance 9-oxo-2(E)-decenoic acid (9-ODA) and its precursor 9-hydroxy-2(E)-decenoic acid (9-HDA), as well as the worker component 10-hydroxy-2 (E)-decenoic acid (10-HDA) and its precursor 10-hydroxy-decanoic acid (10-HDAA). Furthermore, the secretion of 9-HDA and the total amount of mandibular gland pheromone significantly and negatively correlated with elevation. For mtDNA analysis, all samples from Ethiopia clustered with the Y lineage (Apis mellifera simensis) and separated from neighbouring honey bee populations of the A lineage (A. m. scutellata and A. m. monticala). Overall, our results reveal the significant influence of elevation on adaptive traits of Ethiopian honey bees, which are of the same subspecies.
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SUPPORTING INFORMATION :
FIGURE S1. Classical morphometric characters showing the body parts of bees where the 17 measurements were taken.
TABLE S1. Names of apiary sites used for honey bee sampling, their provinces, cardinal locations, and elevation.
TABLE S2. Five reference sequences and their accession numbers belonging to the Cytochrome Oxidase I- Cytochrome oxidase II sub-unit of the mitochondrial DNA of different honey bee sub-species extracted from NCBI database and used for comparative phylogenetic analysis.
TABLE S3. Comparison (Mean ± SEM) of the 17 classical morphometric characters among the regions. Different superscript letters in each column indicate significant differences among the regions according to Kruskal-Wallis test followed by post-hoc Dunn’s test, p < 0.05. Characters which are significantly different among the apiary sites are highlighted in bold.
TABLE S4. Comparison (Mean ± SEM) of the 17 classical morphometric characters among elevation categories. Different superscript letters in each column indicate significant differences among the elevation categories according to Kruskal-Wallis test followed by post-hoc Dunn’s test, p < 0.05. Characters which are significantly different among the apiary sites are highlighted in bold.
TABLE S5. Description of the base pair size of COI-COII intergenic region of the 30 consensus sequences, their haplotypes and percent similarity to sequences found in the NCBI nucleotide database (Blastn).
DATA S1 Data. Raw data.
Keywords
Apiculture, Economic sector, Ethiopia, Honeybee (Apis mellifera), 10-hydroxy-decanoic acid (10-HDAA)
Sustainable Development Goals
SDG-15: Life on land
Citation
WanoWanore, W.W., Pirk, C.W.W., Yusuf, A.A., Baleba, S.B.S., Chege, M., Ndungu, N.N., et al. (2025) Honey bees of Ethiopia: Their lineages and subspecies based on morphometrics, mitochondrial DNA, and mandibular gland pheromone analyses. PLoS One 20(11): e0335551. https://doi.org/10.1371/journal.pone.0335551.