
Bt Corn: Less Insect Damage, Lower Mycotoxin Levels, Healthier
CornBy Kim
Kaplan April 26, 2000Bt corn that has been genetically modified to prevent damage by
European corn borers may also be less likely to harbor mycotoxins, toxins
produced by fungi on corn ears, according to an
Agricultural Research Serviceentomologist. Mycotoxins like fumonisin, a potential cancer-causing agent often
found at elevated levels in insect damaged kernels, are both a health issue and
an export issue. European and Asian markets can refuse to import U.S. corn
because of what they rate as unacceptable levels of mycotoxins. Related ARS research on Bt corn - Versus caterpillars (4/98)
Fumonisins - And beneficial bacteria (1/00)
- And horse disease (2/99)
European corn borers - Repelled by "Ugly Duckling" corn (4/00)
- Lured by aroma of the Gaura plant (2/99)
- Thwarted by fungi (11/97)
Scientists have suspected higher mycotoxin levels may follow
increased insect damage, but ARS entomologist
Patrick
F. Dowd found fumonisin levels 30- to 40-fold lower in Bt corn than in
non-Bt varieties in Illinois cornfields. Bt stands for the biopesticide
Bacillus thuringiensis. Environmental conditions and the specific Bt corn hybrid play
roles in the actual amount of reduction seen, but corn varieties that expressed
the Bt protein throughout the plant rather than in specific areas were the
least likely to have significant fumonisin levels, according to Dowd, who is
with ARS National Center for
Agricultural Utilization Research in Peoria, Ill. ARS is the
U.S. Department of Agricultures chief
in-house research agency. While Bt corn is modified mainly to resist European corn borers,
Bt corn also showed lower levels of mycotoxins when corn earworms were present
in fields, although not as significant a reduction as when European corn borers
were the primary insect pest. This may encourage the creation of corn varieties with more
resistance to a variety of insects in order to provide more protection from
mycotoxins. Small plot studies by Iowa State
University plant pathologist
Gary
Munkvold appear to confirm Dowds findings. Scientific contact: Patrick Dowd, ARS
National Center for Agricultural
Utilization Research, Peoria, Ill., phone (309) 681-6242, fax (309)
681-6686, [email protected]. U.S. Department of Agriculture |