This project is supported by an International Collaborative Research Grant from the Swedish Research Council between the Swedish University of Agricultural Sciences, Uppsala, and the University of Kelaniya, Sri Lanka. The other collaborating institutes in this project are the DWC, FVMAS and SLWHC. The resource persons were Prof. N.P. Sunil-Chandra, Dr. Åsa Fahlman, Dr. Mads Bertelsen, Dr. Vijitha Perera, Dr. Basil Alexander and Dr. Oswin Perera.