Field trials offer hope of conquering food toxin

Maize growing in Nigeria Copyright: Flickr/MikeBlyth

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[LAGOS] The elimination of deadly aflatoxin, which contaminates food crops in Sub-Saharan Africa, is a step closer now scientists have shown that a control method works well in large-scale field trials.

Aflatoxin is a poison produced by the fungus Aspergillus flavus. It contaminates crops such as maize, ground nuts, cassava and yam, either in the field during times of stress — such as drought or insect infestation — or as a result of poor storage conditions.

More than 4.5 billion people in developing countries may be chronically exposed to aflatoxin in their food, putting them at risk of diseases such as cancer. Africa also loses about US$450 million in lost revenue from contaminated export grain.

Scientists from the Nigeria-based International Institute of Tropical Agriculture (IITA), the United States Department of Agriculture and the African Agricultural Technology Foundation in Kenya have been working together to develop a biological control method to reduce the amount of aflatoxin contamination in maize.

A study in 2007 (see Biological control saves maize from toxic invasion) showed that using A. flavus strains that do not produce the toxin to outcompete their toxin-producing cousins can dramatically reduce aflatoxin concentration.

In the past two years, larger field trials have been conducted at 11 sites using a mixture of four benign strains.

Ranajit Bandyopadhyay, a plant pathologist at IITA, told SciDev.Net that this biocompetitive method reduces contamination by 60–99 per cent. "[The trials] proved the robustness of the technology in many growing conditions and gave us more confidence about upscaling the technology widely in Nigeria," he adds.

Farmers in Burkina Faso, Kenya, Malawi, Mozambique, Senegal and South Africa are showing interest in the technology but the benign strains developed are indigenous to Nigeria and may not be suitable for other countries, say the scientists.

IITA researchers will begin further field trials in Nigeria on another 100 hectares in August.

"Finding a donor that can fund this technology on a large scale is a priority," says Bandyopadhyay.

But Niyi Olayiwola, an agricultural economist at the Nigeria’s Development Policy Centre, says that getting farmers to use the technology may not be easy. "It is a good development but farmers value their own traditional ways of doing things," Olayiwola says.