1. Department of Biological Sciences, Abubakar Tafawa Balewa University, Bauchi, Nigeria
2. LLH Bieneninstitut Kirchhain, Kirchhain, Germany
3. Institut für Bienenkunde, Oberursel, Germany
4. Department of Zoology and Animal Welfare, Agricultural University, Kraków, Poland
5. Department of Agroecology, Aarhus University, Flakkebjerg, Denmark