1. Department of Zoology and Entomology, University of Fort Hare , Alice 5700 , South Africa
2. Department of Biological and Environmental Sciences, Walter Sisulu University , Mthatha 5117 , South Africa
3. CSIR–Plant Genetic Resources Research Institute , P.O. Box 7, Bunso Eastern Region , Ghana
4. Department of Agricultural Economics and Extension, University of Fort Hare , Alice , South Africa