April 26, 2005,
ARS News Service: Wild celery and two weed
species found throughout the western United States may
contribute to safe, natural control of the Formosan
subterranean termite, Coptotermes formosanus.
Agricultural Research Service (ARS) scientists say
that, in lab tests, three compounds that they isolated
from these plants scored high kill rates against the
invasive termites, which cause about $1 billion in damage
annually in the United States.
One compound, called apiol, was extracted from wild
celery (Ligusticum hultenii), which is actually
a member of the parsley family. The other compounds
are cnicin, which was isolated from spotted knapweed
(Centaurea maculosa), and vulgarone B, taken
from Artemisia douglasiana, a variant of mugwort.
The compounds were isolated and identified by chemist
Kumudini M. Meepagala at ARS' Natural Products Utilization
Research Unit in Oxford, Miss. Entomologist Weste Osbrink
at ARS' Formosan Subterranean Termite Research Unit
in New Orleans, La., tested them for efficacy.
In those tests, Osbrink, whose unit is part of ARS'
Southern Regional Research Center, found that vulgarone
B and apiol are lethal and fast-acting to the termites.
By the fourth day after application, vulgarone B achieved
a 97 percent mortality rate, and apiol had an 80 percent
rate. Both achieved 100 percent kill rates by the fifteenth
day after application..
Cnicin was slower acting, with an 81 percent mortality
rate 15 days after the treatment.
According to Meepagala, these compounds were present
in high levels in the plants from which they were isolated.
The spotted knapweed from which the cnicin was taken
is a highly invasive weed in the northwestern United
States, while Artemisia douglasiana is found in all
of the western states.
Meepagala had previously shown that vulgarone B is
an effective and fast-acting natural control of golden
apple snails, which devastate Asian rice fields.
ARS is the U.S. Department of Agriculture's chief
scientific research agency.