The current U.S. population of red
imported fire antswhich infest millions of acres across the southern
statescan be traced back to 9 to 20 queens that arrived in Mobile,
Alabama. Photo courtesy of S.D. Porter, ARS.
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Nine to 20 Individual Fire Ant Queens Started U.S. Fire Ant
Population
By Sharon
Durham July 30 , 2008
The current U.S. population of red imported fire ants--which infest
millions of acres across the southern states--can be traced back to nine to 20
queens in Mobile, Ala.
That's according to a genetic study by
Agricultural Research Service (ARS)
entomologist
D.
DeWayne Shoemaker and University of
Georgia entomologist
Kenneth G.
Ross. The results are reported in the Proceedings of
the Royal Society, Biological Sciences.
The red imported fire ant (Solenopsis invicta), native to
South America, is a major invasive pest insect and is considered by the World
Conservation Unit to be among the top 100 worst invasive alien species.
In their study, the scientists found that those original nine to 20
queens stowed away on a boat, presumably each with their worker force, and
began populating the United States in the mid-1930s. These ants spread outward
from the purported initial landing spot in Mobile.
Pinpointing the number of queens needed to account for the genetic
diversity in the current population allows researchers to better develop
biologically-based management practices, predict the invasive potential of the
species, and make inferences about the ecological and evolutionary processes.
Because of the red imported fire ant's status as a major pest, an
enormous amount of research has been conducted on the basic biology of the
species over the past 40 years, making it one of the better known invasive
organisms.
Individuals from two populations in South America and six populations
across the southern United States were collected for genetic analysis. Data
collected substantiates the theory that there is a close genetic resemblance of
ants collected near Mobile to a hypothetical, reconstructed ancestral
population. However, the data also raises the possibility of a secondary
introduction at a location 60 miles west of Mobile.
Further genetic analysis will improve knowledge of the reproductive
biology, population demographics, genetics and invasive history of red imported
fire ants which may assist in controlling them.
ARS is a scientific research agency of the
U.S. Department of Agriculture.