Each year approximately 15% of the world's crops are lost to insect herbivory. Much of this damage is due to Lepidopteran or caterpillar pests and scientists are continually searching for environmentally friendly, non-chemical methods to control them. Previous research using corn lines that are genetically resistant to fall armyworm has identified a novel defense that corn uses to deter herbivores. In response to caterpillar attack, a cysteine protease accumulates in the plant at the caterpillar-feeding site. This protease is similar to papain, the protein-degrading enzyme that is present in meat tenderizers. This defensive protease, called Mir1-CP, has been shown to attack and degrade the peritrophic membrane (PM) of the fall armyworm and other caterpillars. The PM lines the midgut, surrounds the food bolus and protects the insect's digestive track from toxins and pathogens. It is essential for optimal nutrient utilization and PM disruption often results in caterpillar death. This project will determine if there are differences in susceptibility to Mir1-CP among several economically important caterpillar pests. It will determine if PM protein composition contributes to resistance or susceptibility to Mir1-CP attack. Finally, it will determine if the caterpillar is able to recover from exposure to diets containing Mir1-CP. The techniques of proteomics and molecular biology will be used to accomplish the objectives. These objectives directly address one of the broader impacts of this project: to develop a sound understanding of this natural host-plant defense mechanism so that it can be used to control caterpillar pests in corn and other crops. Educational components of the project include recruitment of underrepresented minorities to the laboratory group so as to gain first-hand research experience.
