In Indian villages, the neem tree--a member of the mahogany family--is a 24-hour pharmacy. Its seeds, bark, and leaves are used to treat everything from warts to malaria. The neem tree also repels insects from crops, and that feature has biotechnology companies excited. U.S. scientists have isolated one chemical, azadirachtin, that kills insects in their larval stage, when they are most destructive. After the larva sheds one coat, the chemical prevents it from growing another. Formulas are being marketed by Salt Lake City-based AgriDyne Technologies Inc. and by W.R. Grace & Co. in New York to protect cabbage, cotton, lettuce, tomatoes, and other crops.
That's not the end of the neem story. Both companies are looking into other neem compounds that might turn back enemy insects. They're also screening other plants in cooperation with ethnobotanists, who study how native peoples use plants for food and medicine.