Super colony of Argentine Ants in California

[Scott & Lai 12]

http://www.sfgate.com/cgi-bin/article.cgi?...mp;type=science

Ruthless Argentine Interlopers Assembling World's Largest Ant Colony

Genetic blip has allowed them to flourish in California

New York Times

Monday, August 7, 0

In a quirk of evolution and genetics, Argentine ants are overwhelming native California ants while forming what scientists believe may be the biggest ant colony in the world, stretching more than 600 miles from San Diego to north of San Francisco.

The ants in this so-called supercolony are so genetically similar that different colonies do not fight with one another the way they do in their homeland. As a result, they are using a united family front to win territory from native ants.

In Argentina, where they are known as sugar ants, different nests of the fiercely territorial ants fight with one another, competing for food and space. An ant that wanders into the territory of another colony just 50 yards away will quickly be torn apart by workers, which recognize the peculiar odor of a rival. But in California, scientists found that they could take a worker from San Diego and put it in a colony from San Francisco and it would be welcomed like a kissing cousin.

Using the same DNA fingerprinting techniques used in paternity cases, scientists at the University of California at San Diego looked at the genetic differences between ants in Argentina and California. They discovered more than twice as much genetic diversity among Argentine ants in their native range compared with those in California.

Published reports and museum samples showed that Argentine ants first came to the United States aboard ships carrying coffee and sugar from South America during the 1890s. The scientists concluded that the relatively small immigrant populations created a ``genetic bottleneck,'' choking off genetic diversity. The small founding populations represented less than half the genetic diversity of the species.

That has made almost all Argentine ants in California similar enough that they can no longer distinguish between close kin and ants from other nests, a critical mechanism in the evolution of social insects. So instead of defending separate territories, the ants behave like a single fluid colony in their new territory.

And though the Argentine ants appear to have mellowed out among themselves in California and are mostly just a nuisance to humans, they ruthlessly kill and displace native ants, some of which are 20 times as large as the Argentines.

The DNA detective work by scientists at the UC San Diego capped a five-year investigation of the ecology, behavior and genetics of the ants. By comparing Argentine ants in their native and invaded ranges, the scientists solved an intriguing puzzle in the increasingly important field of invasion biology. Most invasive species move into a territory that has been opened up by changes in habitat and local extinction of native species, said Ted J. Case, a biologist at UC San Diego.

But in the case of Argentine ants, a genetic change set off changes in behavior and colony structure that enabled the invader to conquer new territory by eliminating native species. In Southern California, the small dark brown and black Argentine ants are the No. 1 pest that extermination companies are called to eliminate.

In contrast, it took a week for researchers to even find the ants in Argentina. ``It was eye-opening to see how inconspicuous they were in Argentina,'' Case said. ``Even in areas where they're relatively common, they're not dominant. They're not a pest. So then the question was, what has enabled them to be so successful here?''

By not fighting among themselves, Argentine ants in the supercolony gain a competitive advantage over other ants, said David Holway, a postdoctoral researcher who designed experiments to test the supercolony's advantage over colonies that fight with one another.

The Argentine ants get to food faster, overwhelm rivals with sheer numbers of workers and defend their territory with chemical weapons they spray on opponents. ``The Argentine ants win in a few days,'' Andrew Suarez, a graduate student, said with grim admiration. (Suarez's family came from Argentina.)

He said the experimental results helped explain why some parts of California that were once home to as many as 20 different species of ants now contained as few as two: Argentine ants and a native species that is active in the winter, when the Argentine ants are less active.

Friends and neighbors often ask the researchers how to deal with Argentine ants in their homes. Because their research indicates that lack of moisture is the only factor that seems to limit the spread of Argentine ants, they suggest a simple solution: replacing lush lawns with desert landscaping. ``You wouldn't have them if there were native plants and cactus, and San Diego looked like it should,'' Suarez said.

In their research papers, the scientists have also suggested that more Argentine ants could be introduced to California to increase their genetic diversity so that the ants would again fight with one another and contain their own populations.

Case's laboratory is collaborating with scientists at Clorox who are studying the chemicals that ants smell to identify nest mates. If they could create a chemical that identifies ants as enemies of the supercolony, they might be able to spray the chemical on half of the colony and let the Argentine ants fight to the death.

http://sfgate.com/cgi-bin/article.cgi?f=/c...8/07/MNC301.DTL

This article appeared on page A - 6 of the San Francisco Chronicle

Half the colony has found our apartment

[mawilson 2,133]

Bomb the Argentine!

[Imua 0]

Damn illegals!!!!!

[HAL 9000 96]

Oh no!

[Ban Hammer 13,340]

just goes to show that even the native ants of california have become pussies.

[Peikko 1,575]

Actually, the native Californian ants are interesting, particularly harvest ants - but they have one heck of a sting! Argentine ants are a public nuisance.

[Saddle Bronc 124]

One non-solution (replace one problem with another) is to bring RIFA's (red-imported fire-ants) from East Coast to CA--which will certainly eliminate the Argentines.

[spookyturtle 9,465]

Deport them.

[IAMX 3,055]

Tahm fer me to git mah gun and shewt me sum ter'ist ant scum.