Concentration of moniliformin produced by Fusarium species in grains of transgenic Bt maize hybrids compared to their isogenic counterparts and commercial varieties under European corn borer pressure

In many developing countries, maize is both a staple food crop and a widely-used animal feed. However, adventitious colonisation or damage caused by insect pests allows fungi to penetrate the vegetative parts of the plant and the kernels, the latter resulting in mycotoxin contamination. Maize seeds contaminated with fumonisins and other mycotoxins pose a serious threat to both humans and livestock. However, numerous studies have reported a significant reduction in pest damage, disease symptoms and fumonisin levels in maize hybrids expressing the Bacillus thuringiensis (Bt) gene cry1Ab, particularly in areas where the European corn borer is prevalent. When other pests are also present, the cry1Ab gene alone offers insufficient protection, and combinations of insecticidal genes are required to reduce damage to plants caused by insects. The combination of Cry1Ab protein with other Cry proteins (such as Cry1F) or Vip proteins has reduced the incidence of pests and, indirectly, mycotoxin levels. Maize hybrids expressing multiple Bt genes, such as SmartStax®, are less susceptible to damage by insects, but mycotoxin levels are not routinely and consistently compared in these crops. Bt maize has a greater economic impact on Fusarium toxins than aflatoxins. The main factors that determine the effectiveness of Bt hybrids are the type of pest and the environmental conditions, but the different fungal infection pathways must also be considered. An alternative strategy to reduce mycotoxin levels in crops is the development of transgenic plants expressing genes that protect against fungal infection or reduce mycotoxin levels by in situ detoxification. In this review article, we summarise what is known about the relationship between the cultivation of Bt maize hybrids and contamination levels with different types of mycotoxins.

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Comparison of Bt (Bacillus thuringiensis Berliner) Maize and Conventional Measures for Control of the European Corn Borer (Lepidoptera: Crambidae)

Journal of Entomological Science ◽

10.18474/0749-8004-35.2.118 ◽

2000 ◽

Vol 35 (2) ◽

pp. 118-128 ◽

Cited By ~ 12

Author(s):

Thomas L. Clark ◽

J. E. Foster ◽

Shripat T. Kamble ◽

E. A. Heinrichs

Keyword(s):

Bacillus Thuringiensis ◽

Ostrinia Nubilalis ◽

European Corn Borer ◽

Field Experiments ◽

Control Measures ◽

Bt Maize ◽

Corn Borer ◽

Maize Hybrids ◽

Grain Yields ◽

Plant Length

Field experiments were conducted in 1997 to compare the efficacy Bt (Bacillus thuringiensis Berliner) maize hybrids and two conventional measures for control of the European corn borer, Ostrinia nubilalis (Hübner). Treatments consisted of transgenic Bt maize hybrids and their non-Bt isolines, and isolines treated with a formulated Bt or permethrin insecticide. All control measures significantly reduced O. nubilalis damage in terms of tunnels per plant, length of tunneling, and larvae per plant. The following hierarchy in terms of O. nubilalis efficacy was observed: transgenic Bt > permethrin > formulated Bt > control. In most cases, transgenic Bt maize was most effective in preventing European corn borer damage to ear shanks and generally produced the highest grain yields.

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Comparison of Fumonisin Concentrations in Kernels of Transgenic Bt Maize Hybrids and Nontransgenic Hybrids

Plant Disease ◽

10.1094/pdis.1999.83.2.130 ◽

1999 ◽

Vol 83 (2) ◽

pp. 130-138 ◽

Cited By ~ 223

Author(s):

Gary P. Munkvold ◽

Richard L. Hellmich ◽

Larry G. Rice

Keyword(s):

European Corn Borer ◽

Field Experiments ◽

Fumonisin B1 ◽

Genetically Engineered ◽

Human Consumption ◽

Fusarium Ear Rot ◽

Ear Rot ◽

Bt Maize ◽

Corn Borer ◽

Maize Hybrids

Maize hybrids genetically engineered with genes from the bacterium Bacillus thuringiensis (Bt maize) express CryIA(b) and other Cry proteins that are toxic to certain insects, particularly the European corn borer (Ostrinia nubilalis). Maize kernel feeding by O. nubilalis often leads to infection by fungi in the genus Fusarium, including the fumonisin-producing species F. verticillioides and F. proliferatum. In field experiments in 1995, 1996, and 1997, transgenic maize hybrids and near-isogenic, nontransgenic hybrids were manually infested with neonatal European corn borer larvae. Manual infestation increased Fusarium ear rot severity and fumonisin concentrations in kernels of nontransgenic hybrids. Transgenic hybrids with kernel expression of CryIA(b) consistently experienced less insect feeding on kernels and less Fusarium ear rot than their nontransgenic counterparts. In manually infested treatments, these hybrids also exhibited lower concentrations of fumonisins in kernels compared with their nontransgenic counterparts. In manually infested treatments in 1995, mean fumonisin B1 concentrations were 8.8 μg/g in the nontransgenic hybrid and 6.7 or 3.0 μg/g in transgenic hybrids. In 1996, mean fumonisin B1 concentrations in manually infested treatments were 4.9 μg/g (range 2.3 to 8.8) for nontransgenic and 1.2 μg/g (range 1.0 to 1.3) for transgenic hybrids with kernel expression. Mean total fumonisin concentrations (fumonisin B1 + B2 + B3) were 7.0 μg/g (range 3.0 to 12.2) for nontransgenic and 1.7 μg/g (range 1.5 to 1.9) for transgenic hybrids with kernel expression. In 1997, mean fumonisin B1 concentrations in manually infested treatments were 11.8 μg/g (range 7.6 to 17.3) for nontransgenic and 1.3 μg/g (range 0.8 to 2.2) for transgenic hybrids with kernel expression of CryIA(b) or Cry9C. Mean total fumonisin concentrations were 16.5 μg/g (range 10.7 to 24.0) for nontransgenic and 2.1 μg/g (range 1.5 to 3.1) for transgenic hybrids with kernel expression. Transgenic hybrids that do not express CryIA(b) or Cry9C in kernels did not consistently have fumonisin concentrations different from the nontransgenic hybrids. Higher fumonisin concentrations in nontransgenic hybrids were associated with high European corn borer populations during the early reproductive stages of the maize plants. These results indicate that under some conditions, genetic engineering of maize for insect resistance may enhance its safety for animal and human consumption.

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Relationship between European corn borer resistance and concentration of mycotoxins produced by Fusarium spp. in grains of transgenic Bt maize hybrids, their isogenic counterparts, and commercial varieties

Plant Breeding ◽

10.1046/j.1439-0523.2002.00659.x ◽

2002 ◽

Vol 121 (2) ◽

pp. 146-154 ◽

Cited By ~ 42

Author(s):

T. MAGG ◽

A. E. MELCHINGER ◽

D. KLEIN ◽

M. BOHN

Keyword(s):

European Corn Borer ◽

Fusarium Spp ◽

Bt Maize ◽

Corn Borer ◽

Maize Hybrids

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Influence of growing Bt maize on Fusarium infection and mycotoxins content – a review

Plant Protection Science ◽

10.17221/36/2012-pps ◽

2012 ◽

Vol 48 (Special Issue) ◽

pp. S18-S24 ◽

Cited By ~ 4

Author(s):

J. Nedělník ◽

H. Lindušková ◽

M. Kmoch

Keyword(s):

European Corn Borer ◽

Animal Feed ◽

Fusarium Species ◽

Economic Losses ◽

Insect Damage ◽

Fusarium Spp ◽

Bt Maize ◽

Corn Borer ◽

Mycotoxigenic Fungi ◽

Maize Kernels

The literature linking Bt maize versus non-Bt maize and the changes in the fungal microflora spectrum and in the mycotoxins content have been summarised. The European corn borer reportedly promotes the infection of maize by Fusarium spp. Stalk and ear rots caused by Fusarium spp. are often related to mycotoxin accumulation in maize kernels. As a result, food and animal feed from maize are more severely contaminated with Fusarium mycotoxins: e.g. fumonisins (FUM), deoxynivalenol (DON), and zearalenone (ZEA). Mycotoxins in field maize lead annually economic losses of hundreds of millions of dollars in all regions of the world. The insecticidal proteins in genetically modified hybrid Bt maize reduce insect damage caused by certain Lepidopteran larvae, which in turn can reduce the infection of the grain by the mycotoxigenic fungi. Where such insect damage is a major factor in mycotoxin contamination, Bt maize can lower mycotoxin levels in many cases. The protection of maize plants against insect damage (European corn borer) through the use of Bt technology seems to be one of the ways to reduce the contamination of maize by Fusarium species and mycotoxins.

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