Subversion Among the Ants

Subversion Among the Arts

The U.S. South knows few worse pests than the tiny fire ant, an uninvited guest that came up from South America nearly 50 years ago and settled down for a long visit.The little insects bite people raising painful lumps, attack livestock, nibble crops and foul up ex pensive farm machinery with their hard earthen nest mounds. For years nothing could check their spread; massive at tacks with chemical dusts and sprays all failed. Now it looks as if the Department of Agriculture has finally found an answer to the curse of the fire ants: still smaller ants that seduce the fire ants into destroying themselves.

Social Parasite. Uruguayan scientists working for the department stumbled on the secret while they were searching for a fungus or a bacteria that might be fatal to fire ants. They discovered that in Uruguay, where the ants are native they are no serious problem. Often they are so weak that they build flimsy nests which wash away in the rain. This suggested not an ant killer but a social parasite.

The nests contained various parasites, but the most important turned out to be another species of ants that live without concealment in the fortresses of the fierce fire ants and, by some mysterious influence, make their hosts support them in idle luxury. Usually, a few of the parasites cling to the fire ant queen by means of specially adapted mandibles that fit around her neck without hurting her. When a worker comes to feed her with regurgitated food, the parasites flut ter their antennae, apparently convey ing a compelling message that makes the worker feed the parasites instead of the queen.

The parasites that cling to the queen are females, and when she lays her eggs they lay eggs of their own. Dutifully, the fire ant workers care for both sets of eggs and raise the infant parasites just as if they were young of their own species. The parasites thrive while their considerate hosts all but work themselves to death taking care of them The fire ant economy is wrecked. The Healthy parasites mate conveniently in the nest and then fly away to subvert and weaken other fire ant colonies

Biological Weapon. The parasites have been found only in association with ants Apparently, they cannot live except when fed by the fire ants with their regurgitations. This dependence makes them promising as a potent biological weapon. But the department's scientists will not bring the parasites to the U.S. and turn them loose until it is certain that they will not upset the balance of nature in some unexpected and possibly harmful way.

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