Bacillus Thuringiensis Derived Vegetative Insecticidal Protein Vip3Aa20 as a Potential Aflatoxin Mitigation Tool in Maize (Zea mays)

Aflatoxin contamination is an annual profitability challenge for maize (Zea mays) producers in Texas and other portions of the Southern United States of America. Insects are known to play a key role in the maize infection process by Aspergillus flavus that produce aflatoxin. Transgenic maize hybrids produce Bacillus thuringiensis (Bt) toxins to reduce the level of aflatoxin contamination. This project evaluated the potential effectiveness of incorporating the Vegetative Insecticidal Protein Vip3Aa20 in an integrated aflatoxin mitigation program. Maize variety trait packages evaluated consisted of a non-Bt, Genuity VT Double pro, Herculex, Genuity SmartStax, and Leptra which contained the Vip3Aa20 Bt protein. During the 2014 growing season aflatoxin concentrations ranged from 1.408 μg/kg in the Leptra trait package to a high of 45.97 μg/kg in the non-Bt trait package. Maize that harbored the Leptra trait package significantly reduced the level of aflatoxin compared to all other treatments. In 2015, aflatoxin concentrations ranged from non-detected (<0.0 μg/kg) in the Herculex trait package to a high of 5.64 μg/kg in the Genuity VT double pro trait package; statistical differences between these treatments were not found. Aflatoxin concentrations in 2016 ranged from <0.0 μg/kg in the Herculex treatment to a high of 45.58 μg/kg in the non-Bt trait package; all Bt trait packages had statistically less aflatoxin contamination than the non-Bt trait suite. Aflatoxin concentrations in the Leptra trait package was lower than the non-Bt by an average of 91.8, 51.64 and 95% during the 2014, 2015 and 2016 growing seasons, respectively. Results from this research illustrated that utilization of the Vip3Aa20 Bt-protein reduced aflatoxin contamination in maize and thus, has a high economic potential.

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