1. Department of Biological Sciences, Faculty of Science, University of Ngaoundere, P.O. Box 454, Ngaoundere, Cameroon
2. Higher Teacher Training College of Bertoua, Department of Life Science, University of Ngaoundere, P.O. Box 652, Bertoua, Cameroon
3. Department of Biology and Plant Physiology, Faculty of Sciences, University of Yaoundé I. P.O. Box 812, Yaoundé, Cameroon