CHICAGO, June 6 (Reuters) - The main type of
genetically modified (GMO) corn used in the United
States poses no threat to one common butterfly,
according to a study by University of Illinois researchers
published on Tuesday.

The scientists monitored populations of black swallowtail butterflies
by a field planted with genetically altered corn and found no relationship
between the insects' mortality and pollen from the corn.

``We found that many caterpillars died but not, as far as we could tell, due
 to anything connected to the corn or the corn pollen,'' said May Berenbaum,
head of the university's entomology department. Berenbaum cited spiders,
carnivorous insects and other environmental factors as the main causes of death.

The Illinois researchers conducted studies in the field and in a laboratory.
Their report was published in the Proceedings of the National Academy
of Sciences.

The findings differ sharply from a May 1999 report in which Cornell
University researchers said laboratory tests showed pollen from genetically
altered corn harmed Monarch caterpillars.

The Cornell report last year provided fuel for opponents of gene-altered crops,
some of whom adopted the Monarch butterfly as a symbol of protest.

On Tuesday, the Illinois study findings were hailed by an industry trade
group as a victory for biotechnology.

``This new study, conducted under actual field conditions, should help
clip the wings of last year's stories hypothesizing negative effects of
 Bt corn on monarch butterflies,'' said Dr. L. Val Giddings, vice president
for food and agriculture of the Biotechnology Industry Organisation (BIO).

In the field, the Illinois researchers studied a variety of GMO corn produced
by Pioneer Hi-Bred International Inc., a subsidiary of DuPont Co
(NYSE:DD - news). Known as Bt corn, the plants carry a gene from a
soil bacterium that enables them to produce their own insecticide.

The Bt technology -- used in 15.6 million acres of 20 percent of U.S.
corn plantings this summer --was designed to protect corn plants against
the European corn borer, a costly pest. But the Cornell study sparked
fears about the effects of such GMO corn on non-target insects.

One conclusion of the study, Berenbaum said, is that growers may be
able to customise their corn crop by using different genetic modifications,
known as ``events.''

``There are ways to reduce the risk to non-target organisms at the very
least by event selection,'' she said, just as farmers customise their use
of conventional insecticides depending on environmental risks.

Berenbaum said her team chose to focus on the black swallowtail because
her department has years of expertise with the species, which is common
throughout eastern North America.

Like the Monarch, the black swallowtail feeds on plants located along
the narrow strips between corn fields and roads.