Insect pests and pathogens (fungi, bacteria and viruses) are responsible for severe crop losses. Insects feed directly on the plant tissues, while the pathogens lead to damage or death of the plant. Plants have evolved a certain degree of resistance through the production of defence compounds, which may be aproteic, . antibiotics, alkaloids, terpenes, cyanogenic glucosides or proteic, . chitinases,b-1,3-glu-canases, lectins, arcelins, vicilins, systemins and enzyme inhibitors.
