"It's a very curious phenomenon to have this nutrient amino acid that humans can't live without, yet at the concentrations we put on the leaves, it is toxic to crop-destructive caterpillars," said study co-author Bruce Stevens, professor of physiology and functional genomics in the UF College of Medicine. "It's a completely different class of pesticides that has not been seen before most are toxic to not only the pest, but to people and animals, too."
Stevens first discovered the pesticide properties of methionine while cloning genes that regulate amino acid metabolism in 1998. Working with co-author James Cuda of UF's department of entomology and nematology, Stevens later found this amino acid to be effective against yellow fever mosquito larvae, tomato hornworm and Colorado potato beetle.
Methionine disrupts an ion channel that controls nutrient absorption in larvae with an alkaline intestine, such as in caterpillars of the Citrus Swallowtail. In 2004 and 2007, Stevens obtained two patents for the use of methionine as a pesticide, through the UF Office of Technology Licensing.
"The methionine is sprayed on the leaves, and when the caterpillars begin to eat the leaves, they ingest the compound it's not in the plant itself," Lewis said. "Once they take those first few bites, they don't feed again and remain stationary until they die."
Methionine is low-cost and serves as fertilizer if it reaches the ground because it's a biodegradable nitrogen source, Stevens said. The amino acid is mass produced and has been used as a nutritional supplement in outdoor livestock feed since the 1960s. The U.S. Department of Agriculture recently approved the use of methionine for organic poultry production.
"This is a neat idea and I'm hoping that more work will be done on this in the f
|Contact: Richard Levine|
Entomological Society of America