Insect Damage, Aflatoxin Content, and Yield of Bt Corn in Alabama

Area of Science:

• Agricultural Science
• Entomology
• Plant Breeding

Background:

• Corn is a vital crop in the southeastern US, susceptible to insect damage and aflatoxin contamination.
• Genetically modified (GM) corn, specifically Bt corn, has been developed to enhance insect resistance.
• Understanding the impact of various Bt traits on yield and aflatoxin is crucial for sustainable agriculture.

Purpose of the Study:

• To evaluate the efficacy of different Bt corn traits in reducing insect damage and increasing yield.
• To assess the influence of Bt traits on aflatoxin levels in corn.
• To determine the correlation between insect damage, yield, and aflatoxin under field conditions.

Main Methods:

• Field trials were conducted at eight Alabama sites over three years using isoline pairs of hybrid corn.
• Corn hybrids incorporated various Bt traits: YieldGard Corn Borer (Cry1Ab), Herculex I (Cry1F), Genuity VT Triple PRO (Cry1A.105, Cry2Ab2), Agrisure Viptera 3111 (Vip3Aa20, Cry1Ab), and Genuity SmartStax (Cry1A.105, Cry2Ab2, Cry1F).
• Evaluated parameters included insect damage, crop yield, and aflatoxin levels, with comparisons between Bt-containing and non-Bt isolines.

Main Results:

• Corn hybrids with Bt traits exhibited significantly lower insect damage and higher yields compared to non-Bt counterparts across all tested sites and years.
• While Bt traits reduced insect damage, this reduction was not consistently correlated with yield improvements.
• Bt traits expressing multiple insecticidal proteins offered superior protection against corn earworm compared to single-protein traits.
• Yields and aflatoxin levels varied significantly across locations; irrigated sites generally produced higher yields.
• Aflatoxin levels showed no consistent association with any evaluated factors, including Bt traits, temperature, or moisture.

Conclusions:

• Bt corn traits effectively reduce insect damage and enhance yield in Alabama field conditions.
• The efficacy of Bt traits can vary, with multi-protein traits offering broader insect protection.
• Aflatoxin contamination remains a complex issue in the southeastern US, influenced by environmental factors rather than solely by Bt traits.
• Further research is needed to understand and mitigate aflatoxin accumulation in corn, irrespective of genetic modification.