“Ground-truthing” efficacy of biological control for aflatoxin mitigation in farmers’ fields in Nigeria: from field trials to commercial usage, a 10-year study

Authors: BANDYOPADHYAY, RANAJIT - International Institute Of Tropical Agriculture (IITA); ATEHNKENG, JOSEPH - International Institute Of Tropical Agriculture (IITA); ORTEGA-BELTRAN, ALEJANDRO - International Institute Of Tropical Agriculture (IITA); AKANDE, ADEBOWALE - International Institute Of Tropical Agriculture (IITA); FALADE, TITILAYA D.O. - International Institute Of Tropical Agriculture (IITA); Cotty, Peter

Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/21/2019
Publication Date: 11/8/2019
Citation: Bandyopadhyay, R., Atehnkeng, J., Ortega-Beltran, A., Akande, A., Falade, T., Cotty, P.J. 2019. “Ground-truthing” efficacy of biological control for aflatoxin mitigation in farmers’ fields in Nigeria: from field trials to commercial usage, a 10-year study. Frontiers in Microbiology. 10. https://doi.org/10.3389/fmicb.2019.02528.
DOI: https://doi.org/10.3389/fmicb.2019.02528

Interpretive Summary: Aflatoxin contamination of food and feed presents human and animal health risks, including cancer, stunting, and immune system suppression, and results in loss of crop value from due to aflatoxin regulation in lucrative international markets. Biological control of aflatoxins through the application of non-aflatoxin-producing isolates of Aspergillus flavus has been used Nigerian corn and peanut fields since 2009, initially as a field trial and then commercially starting in 2013. Crops from treated fields had significantly higher recovery of the biocontrol isolates and 80% less aflatoxin than untreated field, and consequently more treated fields than untreated fields yielded crops with less aflatoxin than allowed by regulatory standards. Biocontrol has proven itself an effective treatment to reduce aflatoxin and increase crop value by allowing access to international markets.

Technical Abstract: In sub-Saharan Africa (SSA), diverse fungi belonging to Aspergillus section Flavi frequently contaminate staple crops with aflatoxins. Aflatoxins negatively impact health, income, trade, food security, and development sectors. Aspergillus flavus is the most common causal agent of contamination. However, certain A. flavus genotypes do not produce aflatoxins (i.e., are atoxigenic). An aflatoxin biocontrol technology employing atoxigenic genotypes to limit crop contamination was developed in the United States. The technology was adapted and improved for use in maize and groundnut in SSA under the trademark Aflasafe. Nigeria was the first African nation for which an aflatoxin biocontrol product was developed. The current study includes tests to assess biocontrol performance across Nigeria over the past decade. The presented data on efficacy spans years in which a relatively small number of maize and groundnut fields (8–51 per year) were treated through use on circa 36,000 ha in commercially-produced maize in 2018. During the testing phase (2009–2012), fields treated during one year were not treated in the other years while during commercial usage (2013–2019), many fields were treated in multiple years. This is the first report of a large-scale, long-term efficacy study of any biocontrol product developed to date for a field crop. Most (>95%) of 213,406 tons of maize grains harvested from treated fields contained <20 ppb total aflatoxins, and a significant proportion (>90%) contained <4 ppb total aflatoxins. Grains from treated plots had preponderantly >80% less aflatoxin content than untreated crops. The frequency of the biocontrol active ingredient atoxigenic genotypes in grains from treated fields was significantly higher than in grains from control fields. A higher proportion of grains from treated fields met various aflatoxin standards compared to grains from untreated fields. Results indicate that efficacy of the biocontrol product in limiting aflatoxin contamination is stable regardless of environment and cropping system. In summary, the biocontrol technology allows farmers across Nigeria to produce safer crops for consumption and increases potential for access to premium markets that require aflatoxin-compliant crops.