in modern times frontier science has been able to avert dangers posed by extreme climatic events and new pests and diseases in ways that traditional knowledge alone could not have matched the biological control of the cassava mealy bug in africa by the use of a pathogen imported from south america is an excellent example of modern science contributing to the protection of a traditional farming system many authors have decried the loss of the vast range of landraces that were used by many traditional farmers as a protection measure against climate extremes and pest and disease threats much of the world s rice now comes from a tiny number of improved cultivars most of them highly dependent on fertilizers and pesticides