Nov 17 Crop-devouring armyworms are showing
increasing resistance in some U.S. farm fields to a popular type
of genetically modified crop that should kill them, scientists
said on Monday.
The evolution of insect resistance "is a great threat" long-
term to the sustainability of the GMO crop biotechnology that
has become a highly valued tool for many U.S. farmers, according
to Fangneng Huang, an entomologist at Louisiana State University
(LSU) and lead researcher for a three-year study.
The study was published on Monday in the PLOS One online
journal (www.plosone.org) for peer-reviewed research,
after being presented at the Entomological Society of America
annual meeting in Portland, Oregon.
The research documents resistance by fall armyworms in the
southeastern United States to the Cry1F protein found in many
corn products developed Dow AgroSciences and DuPont
to fight off the destructive pests.
It is the latest evidence in recent years showing that
insects are developing resistance to crops that have been
genetically modified to kill them.
Like the "super weeds" that have developed resistance to
glyphosate-based herbicide and make it harder for farmers to
keep fields from being overrun with weeds, the armyworms are
starting to devour corn crops that should repel them, said
Dominic Reisig, an entomologist at North Carolina State
Armyworms can be a problem for farmers in many U.S. states,
but the resistant armyworms have been documented only in some
areas of Florida and North Carolina. The range of these
resistant armyworms is unknown, researchers said.
They said farmers should plant more non-GMO corn as a refuge
and possibly increase the use of pesticides to control the
Dow and DuPont did not respond to requests for comment.
The GMO corn at issue contains Bacillus thuringiensis (Bt)
genes. Bt corn, popular with farmers throughout the Americas,
has been on the market roughly 18 years. Newer types of Bt corn
with multiple modes of action are still showing effectiveness,
"We don't know how long they can last," Huang said.
Researchers have also expressed concerns about Bt resistance
in western corn rootworm.
The study was conducted by researchers from LSU, North
Carolina State University, the University of Florida, the U.S.
Department of Agriculture, the University of Minnesota and the
University of Georgia.
Financial support came in part from USDA.
(Reporting by Carey Gillam in Kansas City; Editing by Dan