Study links success of invasive Argentine ants to d...(neydew from aphids or scales. The ch...)

The change in the ants diet not only allows them to survive as they eliminate their food of native insects. But because much more plant material than insect protein is available in irrigated residential communities, this switch to carbohydrates allows the ants to effectively expand their populations, the scientists say.

By virtue of this great dietary flexibility, Argentine ants are able to consume a variety of sources of food and its this ability to consume carbohydrates that contributes to their success, said Holway.

Holway and Suarez found that another reason for the Argentine ants success was the lack of genetic diversity among ant colonies up and down the California coast. That study, published in 2000 in the Proceedings of the National Academy of Science, was conducted when Suarez, now an assistant professor of entomology and animal biology at Illinois, was a UCSD graduate student,

The scientists concluded that this reduced genetic variation had allowed a giant supercolony of closely related ants to grow unchecked from San Diego to Ukiah, 100 miles north of San Francisco. In Argentina, by contrast, fighting among the more genetically dissimilar, territorial ants managed to keep these insects in check and in smaller, much more sharply defined colonies than those in California.

The tiny dark-brown and black Argentine ants, which are about two millimeters in length, are thought to have entered the United States aboard ships carrying coffee or sugar from Argentina during the 1890s, then expanded throughout California and the southern parts of the United States. In the Southeast and much of the South, their proliferation is now limited to some extent by the introduction of fire ants.

But in California, where those competitors are largely absent, the ants thrive in the mild coastal regions, killing and displacing native ants, many of which are 10 times larger in size. Their growth ha
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