The Italian history of crop protection has been dominated by the use of agrochemical, generally having a negative impact on the environment and residues in final products. The approach based on the use of genotypes with low susceptibility to biotic stresses searching for sources of resistances was largely uninvestigated for long time. Only recently researchers focussed their studies on this subject. Studies devoted to this subject are very difficult mainly for permanent crop such as the olive tree because time consuming and because it is very hard to compare the behaviour of a large germplasm in the same pedoclimatic condition. Furthermore, it is very hard to design tests of resistances under controlled conditions because of the difficulty due to the hard tolerance of captivity of pests such as olive fly and many others. In any case, recently research activities on this field has been greatly improved and several research projects are supported by many institutions.