SAN FRANCISCO, Sept. 14 - Pesticides haven't stopped them. Trapping hasn't worked, either. But now chemists and biologists at the University of California, Irvine, (UCI) think they may have found a natural way to finally check the spread of environmentally destructive Argentine ants in California and elsewhere in the United States: Spark a family feud.

The preliminary finding, by UCI organic chemist Kenneth Shea, evolutionary biologist Neil Tsutsui and graduate student Robert Sulc, was described today at the 232nd national meeting of the American Chemical Society, the world's largest scientific society.

Slight alterations in the "recognition" chemicals on the exoskeletons of these closely related pests, these scientists say, could transform "kissing cousins" into mortal enemies, triggering deadly in-fighting within their normally peaceful super colonies, which have numerous queens and can stretch hundreds of miles. One colony of Argentine ants is believed to extend almost the complete length of California, stretching from San Diego to Ukiah, 100 miles north of San Francisco. Their sheer numbers, cooperative behavior and lack of natural predators in the United States make these small, slender ants - only about 1/8 of an inch long - difficult to eradicate, Tsutsui and Shea say.

The ants use chemical cues on their exoskeletons to recognize other members of their colony. Because Argentine ants in the California super colony are so interrelated, they have similar "recognition" cues and generally cooperate with each other. But in their preliminary laboratory work, Shea and Tsutsui were able to create a slightly altered, synthetic version of one of these "recognition" compounds, which was composed mainly of linear hydrocarbons with one- to three-side chains called methyl groups. When coated onto experimental Argentine ants, the synthetic recognition compound caused untreated nest mates to attack.

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14-Sep-2006