Protease inhibitors in crop protection from insects

World wide crop losses without the use of pesticides and other non-chemical control strategies is estimated to be about 70% of crop production, amounting to U.S. $ 400 billion. Many insect pest families are known which cause serious damage to agriculture crops. Insect pest menace is one of the major factors that destabilize crop productivity in agricultural ecosystems. They are responsible for severe reduction in crop yields, in spite of extensive use of chemical pesticides. Plant traits that are important for resistance to insect pest attack are complex and operate on many spatial scales involving direct and indirect defenses. Protease inhibitors (PIs) are one class of plant defense proteins against insect pest infestation. Plant derived protease inhibitors inactivate proteases of animals and microbial origin while rarely, inhibiting endogenous enzymes is a compelling evidence for the current view that they are involved in the protection of plants against pests and possibly pathogens. They are one of the prime candidates with highly proven inhibitory activity against insect pests and also known to improve the nutritional quality of food. Efforts are being made to explore their use in developing insect resistance in susceptible crop plants. However, a thorough understanding of insect digestive enzymes and protease inhibitors is a prerequisite to plan strategies for successful and sustainable application of PIs. KEYWORDS