ITHACA, N.Y. -- Scratching the surface of wild tomatoes that bugs don'tbother, Cornell University scientists discovered the plants' chemicalsecret for repelling insect pests: a complex, waxy substance thatcommercially grown tomatoes have "forgotten" how to make.
A simplified formulation of the wild tomatoes' chemical has been granted aU.S. patent on "Non-cyclic Esters for Pest Control" and could become thenext-generation nontoxic insect repellent for a long list of crops onhungry bugs' menu.
The newly patented compounds may work, in part, because they create stickysurfaces that insects don't like, and also because the compounds break downto release short-chain fatty acids, which are known to repel insects.
"We've made smaller versions of natural fats that are easily biodegraded tofatty acids," said Bruce Ganem, a Cornell chemist and co-inventor, alongwith Martha A. Mutschler, professor of plant breeding. "These are similarin structure to the natural triglycerides in our bodies, only with shorterfatty acids, and the amounts that will be on crops seem unlikely to pose ahealth hazard to humans." Ganem is the Franz and Elisabeth RoesslerProfessor of Chemistry in Cornell's College of Arts and Sciences.
Two insect larval pests, the tomato fruitworm (Helicoverpa zea) andthe beet army worm (Spodoptera exigua), cause an estimated $30million a year in damage to the processing-tomato crop inin California.The grubs bore holes in tomato fruits, allowing decay organisms to enterthe skin and spoil the fruit. But when the Cornell pest-control chemicalis sprayed on tomatoes, damage from tomato fruitworm and beet army worm isgreatly reduced or eliminated altogether.
In addition to tomatoes, the patented chemical agents are expected toprotect a wide range of crop plants and ornamental plants against more than30 kinds of mites, beetles, leafminer flies and whiteflies, aphids,leafhoppers, mealy bugs, worms and thrips, the Cornell inventors said. Andthe same insect species that are repelled from eating the plants also areless likely to oviposit (lay eggs), thus breaking a cycle of plantdestruction, the scientists added.
The Cornell scientists began their discovery process by selecting wildtomatoes (Lycopersicon pnennellii, the relative of a commonlycultivated tomato, L. esculentum) with few insect blemishes, thenwashing the fruit to obtain the natural compounds for chemical analysis.The exact mixture of glucose esters and other compounds would have been toocomplicated to duplicate, Ganem said, so they narrowed their formulation tosome simple analogs with common structural and physical properties.
"Now the chemistry is easy," Ganem said, noting that the patent coversseveral similar formulations of the pest repellent. The "non-cyclic" termmeans each compound's carbon atoms are arranged in chains, rather than inrings.
Mutschler and Ganem hope to take their invention to the next stage -- amarketable product with all the emulsifiers and stabilizers that areexpected by consumers -- through a Technology Development Fund Grant fromCornell's Office of Economic Development.
Materials provided by Cornell University. Note: Content may be edited for style and length.
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