Electric Shock is Bad News for
October 6, 2000
Shocking fire ants with electricity
stimulates release of an attractant that lures ant- attacking Brazilian phorid
flies to the ants, according to Agricultural
Research Service scientists. Fire ants infest 300 million acres in the
southern United States. Electric shock won't be an ant-control measure. But the
scientists think the finding might help them speed laboratory production of
flies for outdoor release against the ants.
Phorid flies are natural enemies of red imported fire ants in South America.
ARS scientists brought the flies to this country and released them to help
reduce U.S. fire ant populations. Since that 1997 release, the flies have
survived three winters in Gainesville, Fla., where their numbers and
distribution have expanded rapidly.
Researchers at ARS Center for
Medical, Agricultural and Veterinary Entomology in Gainesville were looking
into why ants are attracted to electrical devices. The scientists discovered
that fire ants walking across an electrically energized grid release a natural
chemical that attracts phorid flies as well as other fire ants. This chemical
draws a six-fold increase in the number of flies attacking the ants.
Once a parasitic phorid fly locates an ant, it swoops down on the ant,
pierces its body, and deposits an egg inside the ant. The egg hatches into a
larva within a dayor two. The larva then moves into the ants head,
causing the head to fall off. The larva completes its development in the
ants head. Electrical stimulation helps increase production of
parasitized ants in the laboratory, which in turn increases the number of
phorid flies available for release into fire ant field populations.
The scientists are trying to isolate the specific chemical ants release when
shocked with electricity. This information will help scientists rear phorid
flies in the laboratory, monitor natural fly populations and their
effectiveness in reducing fire ant populations.
ARS is the U.S. Department of
Agricultures principal research agency.
Scientific contact: Robert K. Vander Meer and Sanford Porter,
Imported Fire Ant and Household
Insects Research Unit, ARS Center for Medical, Agricultural and Veterinary
Entomology, Gainesville, Fla., phone (352) 374-5914, fax (352) 374-5818,