The New York Times,
January 11, 2005Link
The Harvard entomologist Edward O. Wilson believes that he has solved a 487-year-old ecological mystery.
In 1518, a spectacular plague of ants devastated some of the earliest Spanish settlements in the New World on the island of Hispaniola. The Spanish historian BartolomÔ¿½ de las Casas recorded how entire plantations were wiped out ''as though fire had fallen from the sky and scorched them.'' Despite the scale of the destruction, the identity of the plague ants has never been discovered.
Dr. Wilson, an expert on ants, enlisted historians to help him solve the mystery. He used details in contemporary accounts to narrow the field of possible species. Among the most telling clues were the ants' stinging bite and their habit of living among plant roots. Only one species on Hispaniola today fits Dr. Wilson's profile, the tropical fire ant, Solenopsis geminata.
Yet fire ants do not eat plants. As Dr. Wilson points out, they obtain much of their food from sap-sucking insects like mealybugs and scale insects. The sap-suckers secrete water loaded with sugar and amino acids, which the ants drink. In turn, the ants defend the sap-suckers from predators with their stinging bite.
Dr. Wilson suspects that the 1518 outbreaks occurred after the Spanish colonists had introduced new species of sap-suckers to Hispaniola. He notes that the first shipment of plantains arrived there from the Canary Islands in 1516. After the native tropical fire ants began protecting them, the sap-suckers exploded.
''The Spanish would not have made the connection,'' Dr. Wilson said. ''They'd be paying attention to the ants' stinging them every time they were handling a plant.''
Dr. Wilson described his findings in the Jan. 6 issue of Nature. He also examined major outbreak in the Lesser Antilles in the 1760's. Those ants were clearly different. For one thing, they did not bite. Dr. Wilson proposes that the culprit was the big-headed ant, Pheidole megacephala. A native of Africa, the ant is currently causing agricultural damage in other parts of the tropics where it has been accidentally introduced. The Lesser Antilles may have been one of the first places the ant invaded and wreaked havoc.
Invasive species represent major threats to farmers and endangered native species. If Dr. Wilson is right, they had major effects in the New World from the earliest days of European exploration. ''Almost as soon as the first Europeans got there, it started,'' he said.
For now, however, Dr. Wilson cautions that he has identified just the most likely suspects of the ant plagues.
''I have enough for an indictment,'' he said. ''I'm prepared for the grand jury.''
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