@INBOOK {HERREN:1990, title = {The Africa-wide Biological Control Program}, author = {Herren, H. R. }, year = {1990}, type = {Integrated pest management for tropical root and tuber crops, edited by S.K. Hahn and F.E. Caveness}, pages = {33--41}, publisher = {International Institute of Tropical Agriculture (IITA)}, address = {Ibadan, Nigeria}, }