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Daily News Archive
From July 17, 2002

Natural Compound in Tomatoes Repels Pests

North Carolina State University scientists have discovered that a substance produced by tomatoes repels mosquitoes and other insects more effectively than DEET. Entomology professors at NC State, Dr. Michael Roe and William Neal Reynolds, showed that the natural compound found in tomatoes is so effective at repelling insects that the university patented the substance.

The university has since licensed the right to produce the substance as an insect repellent to Insect Biotechnology Inc., a Durham company that specializes in developing and marketing biochemical insecticides. Funding for the research was provided in part by the National Science Foundation (NSF), the N.C. Biotechnology Center, the N.C. Agricultural Research Service, and Insect Biotechnology. Roe's research was also supported by university overhead receipts.

Roe and Insect Biotechnology Inc. officials believe the substance, which Insect Biotechnology is calling IBI-246, has the potential to replace DEET as the active ingredient in most insect repellents.

DEET (short for N, N-diethyl-meta-toluamide) is a commonly used, yet controversial, insect repellent. Scientists have raised concerns about DEET's toxic properties when used alone and in combination with other chemicals. The use of products containing DEET have been associated with rashes, swelling and itching, eye irritation and, less frequently, slurred speech, confusion and seizures. Products with high concentrations of DEET are considered hazardous to children particularly, and the EPA no longer allows claims on labels of products containing DEET that the product is safe for children. Recent research at Duke University with rats showed that frequent and prolonged use of DEET caused brain-cell death and behavioral changes in the animals.

Roe said he discovered the repellent capacity of IBI-246 by accident. "I was listening to a scientific presentation about protein mimics as a diet pill for the control of mosquito larvae," Roe said. He realized that the compounds being discussed were similar to a compound found in wild tomatoes that Roe and another NC State
entomologist, Dr. George Kennedy, had studied a number of years earlier.

Roe and Kennedy had studied the compound, which apparently is part of the tomato's natural defenses against insects, to see if it might be used to control worms that eat tomatoes. Roe revisited the compound and tested it as a mosquito repellent.

He found that it not only repelled mosquitoes, but ticks as well. Bennett said subsequent testing has shown that the substance also repels fleas, cockroaches, ants and biting flies, as well as insects that are agricultural pests such as aphids and thrips. Roe said the compound is already used to make cosmetics.

Bennett added that the cost of producing IBI-246 is expected to be competitive to the production cost of DEET.
Bennett said Insect Biotechnology has applied to the EPA for approval to use IBI-246 as an insect repellent in several products. While it is impossible to tell how long the approval process will take, Bennett said he is hopeful IBI-246 will win EPA approval by the end of the year.

For more information, contact Dr. Michael Roe, 919-515-4325 or michael_roe@ncsu.edu; Dr. John Bennett, 919-484-1429, Paul K. Mueller, News Services, 919-515-3470 or paul_k_mueller@ncsu.edu.

For more information about mosquitoes and alternative pest management, please contact Beyond Pesticides.

Source: North Carolina State University.