Washington, Jan 18 (IANS) Researchers have figured out how a key amino acid, methionine, vital for human nutrition, can also knock out caterpillars threatening the citrus industry.

The Lime Swallowtail, or Citrus Swallowtail, is a well-known agricultural pest from southern Asia discovered in the Caribbean in 2006, and researchers say its potential impact on the US citrus industry is cause for serious concern.

“Everything that’s in the Caribbean eventually gets to Florida - Florida is an invasive magnet,” said University of Florida lepidopterist Delano Lewis who led the study.

“That’s why we’re trying to make the first strike to see how to stop it,” he added, the Journal of Economic Entomology reports.

Experiments conducted at the university’s McGuire Centre for Lepidoptera and Biodiversity show that when methionine is sprayed on leaves, it is 100 percent effective in killing larvae of the Lime Swallowtail caterpillars within two to three days.

If not controlled, the caterpillars can completely defoliate young wild lime plants.

Methionine is needed in the human diet for many reasons, including protein-building and metabolism. It is environmentally safe and harmless to citrus plants, mammals and birds, according to a university statement.

“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 Florida College of Medicine.