Aflatoxins produced by the fungi Aspergillus flavus and Aspergillus parasiticus are potent liver carcinogens. They commonly grow on corn in the southern United States. In 1996, transgenic Bt corn was planted in the US. Further, Bt corn contains vegetative insecticidal proteins (Vip) which were commercialized in 2011. The first study evaluated the effects of Bt corn, containing Bt corn, irrigation, and climate factors on aflatoxin risks in six southern US states from 2011-2016 by using corn growers' crop insurance claims as an analysis. The results showed that the higher adoption rate in Vip-containing Bt corn and total Bt corn, and irrigation reduced aflatoxin contamination in the southern US. In addition, the drought in July and wet September increased the risk of aflatoxin. The second study was aimed to understand the impacts of different Bt hybrids: Bt corn containing lepidopteran control, Bt corn containing corn rootworm control, and Bt corn containing both lepidopteran and corn rootworm control on aflatoxin- and drought-related insurance claims in the Southern US from 2003-2016. We found that Bt corn contains lepidopteran traits and was associated with lower aflatoxin risks. Moreover, the stacked hybrids that protect against both lepidopteran pests and corn rootworm had an additive effect on reducing aflatoxin risks. All three different Bt hybrids were associated with fewer drought risks, but Bt corn that targets corn rootworm had more effects on it. Overall, these results suggest that Vip-containing Bt corn has the potential to be used in reducing the aflatoxin damage. Bt corn and irrigation practice can also be the two strategies to reduce both aflatoxin and drought risks in commercial US corn fields.
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