story to find out more.
Nematodes Fight Biobattle Against Biting
Flies By Jan
July 1, 2002
Flies that pester cattle in the feedlot could meet their match
in tiny parasitic roundworms now being tested as biological control agents by a
pair of Agricultural Research Service (ARS) and University of Nebraska-Lincoln (UNL) scientists.
ARS entomologist David Taylor says their research aims to find
out whether the roundworms, or nematodes, can provide cattle producers with a
reliable alternative to chemical insecticides, which often must be reapplied as
fly populations rebound or migrate in from other sites. In the nematodes--which
includes the species Steinernema feltiae--Taylor and UNL associate
Thomas Powers also see a way to delay the emergence of insecticide-resistant
Nationally, flies cost the beef and dairy cattle industry up to
$1 billion in annual production losses. The chief targets of Taylor and Powers'
research are house and stable flies, especially the latter. Attacks by swarms
of the relentless biting flies on cattle cause blood loss, stress and
feed-efficiency problems. Both fly species can also be a nuisance to animal
handlers and homeowners whose properties are close to cattle operations, notes
Taylor, with ARS'
Livestock Insects Research Unit in Lincoln, Neb.
Since 1999, the two researchers have screened about 20 species
and 50 strains of fly-infecting nematodes. Of special interest are those
capable of surviving in manure around feedlots or soiled bedding in calf pens,
where 80 percent of the flies' brood hatch and feed. The nematodes kill the
flies' maggot offspring by wriggling into their bodies to feed, mate and
reproduce. In experiments, up to 99 percent of fly maggots died within 48 hours
of infection by S. feltiae, the researchers' top fly-fighter.
A more in-depth article about this work appears in the
July issue of
Agricultural Research magazine.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.