“this study is going to cause quite a stir.” — MIcHAEl GooDISMAN
U.S. is biggest exporter of fire ants
Biologists had certainly considered
this United States–bridgehead scenario
of invasions, Ross says, “but without
data, it was anybody’s guess.” To track
the invasions, an international research
team analyzed ants from 2,144 colonies
in a total of 75 places in 11 countries
and looked at several kinds of genetic
information, including dozens of
DNA markers.
By Susan Milius
Genetic evidence now spotlights the
United States as the source of recent
fire ant invasions in the rest of the world.
The aggressive, stinging fire ants
(Solenopsis invicta) aren’t native to
the United States but rather to a broad
swath of South America. Yet the south-
ern United States, invaded by fire ants
in the 1930s, has sent off at least eight
separate waves of fire ant
invasions to other coun-
tries in recent years, says
entomologist Kenneth
“Most studies don’t come close to
those numbers,” says Goodisman.
Ross of the University
of Georgia in Athens.
A ninth invasion probably hopscotched from
the South to California
before hitting Taiwan.
“It’s not good news,”
Ross says. These waves of
ants are now colonizing
the Caribbean, Australia,
New Zealand, Taiwan
and China, including
Native to South America,
fire ants are using the U.S.
South as a jumping-off point
to invade other shores.
Hong Kong and Macau, he and his colleagues report in the Feb. 25 Science.
Scott Bauer/uSDa agricultural reSearch Service, BugwooD.org
“This study is going to cause quite a
stir,” says geneticist Michael Goodisman
of Georgia Tech in Atlanta, who studies
invasive ants. The new fire ant research,
he notes, “could have important trade
and travel implications.”
Regardless of any furor, the study is a
valuable step in dealing with the prob-
lem, says another invasive-ant biologist,
Ben Hoffmann in Darwin, Australia,
with the country’s CSIRO research ser-
vice. “We need to know how invasions
spread to be able to prevent spread and
effectively manage invasions.”
Ross explains that looking closely at
fire ants in their native range in South
Even without special adaptations,
basic fire ant biology gives the species
some tricks for traveling. In the ants’
native range, they survive flooding by
fleeing their nests with their young and
gripping each other to create a living raft
of ants that floats until the flood sub-
sides. If they’re afloat for longer than
they can survive without food, adults
eat the young.
Worm history 101
lazy and busybody worms don’t
just look and act different; they’re
evolutionarily distinct. in the March
3 Nature a german team presents a
DNa analysis showing that annelids,
a group including earthworms and
leeches, split into two divisions hun-
dreds of millions of years ago — the
mobile errantia and the mostly sed-
entary Sedentaria. Scientists noticed
the different creepy-crawly lifestyles
long ago, but whether the changes
had sprung from a true evolutionary
split wasn’t clear. — Daniel Strain
Dam cane toads
Keeping cane toads away from
human-made water sources in australia might reduce the amphibians’
future spread by about a third under
ordinary climate conditions. the
invasive toads may be susceptible
to a strategy that would essentially
close down hubs from which the
toads radiate, say Daniel florance
of the university of Sydney and his
colleagues. invasion theorists have
floated hub-blocking as a general
strategy, but now fencing experiments and data on toad movements
suggest a test case, the researchers say in a paper posted online
february 23 in the Proceedings of
the Royal Society B. — Susan Milius
Heartless beast
a lump in the chest cavity of a
Thes-celosaurus dinosaur, once proposed
to be fossilized heart muscle, is
probably just cemented sand grains,
a North carolina team reports in
the March Naturwissenschaften.
the dinosaur gained worldwide
headlines in 2000 after a paper in
Science made the heart claim (SN:
4/22/00, p. 260). — Alexandra Witze
www.sciencenews.org
March 26, 2011 | science news | 15
