A western corn
rootworm searches for pollen on corn silk. The pest costs U.S. growers about $1
billion annually in yield losses and control measures. Click the image for
more information about it.
Study Probes Spread of U.S. Corn Pest in
Europe By Luis
Pons November 10, 2005
The Agricultural Research Service (ARS) has helped shed new light on the spread
in Europe of the western corn rootworm beetle, the most destructive pest of
corn in the United States.
It was thought that the European spread of this pest, Diabrotica
virgifera virgifera, could be traced exclusively to its accidental 1992
introduction from North America into the former Yugoslavia.
But a new study, headed by researchers Thomas Guillemaud and Nicholas
Miller at Institut National de la Recherche Agronomique (INRA) in Sophia Antipolis, France, has found
that its the result of at least three independent transatlantic
introductions. This suggests that such incursions may be occurring more often
than previously thought.
The study, described in the current issue of Science, entailed analysis of genetic
variation in European and American western corn rootworm populations,
specifically at eight microsatellite loci within their DNA.
Seok Kim of ARS
Insects and Crop Genetics Research Unit in Ames, Iowa, developed the
microsatellite DNA markers needed for the study. His work and ARS cooperation
with INRA accelerated the research findings by about a year.
ARS is the U.S. Department of
Agricultures chief scientific research agency.
Western corn rootworms cost U.S. growers about $1 billion annually in
yield losses and control measures. Young larvae feed on root hairs and small
roots, while larger larvae feed on primary roots.
Kim explained that the pests are usually most easily controlled by
rotating crops between corn and soybean. Eggs laid in corn hatch during the
soybean phase, depriving the pests of suitable food.
He added that the findings also bear significance because of the
emergence of a new variant of the western corn rootworm in the United States
that lays its eggs in soybeans and whose offspring hatch in corn. This variant
has not yet been detected in Europe.