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How fungal biopesticides can reduce aflatoxins in grain crops

Theme: Biocontrol agents

The presence of biocontrol and biopesticide products in the crop protection market is increasing, not just because of their capacity to control pests and diseases effectively but also their high levels of safety with regards to human health and the environment. Whilst their use against crop pests and diseases is becoming well known, a use that perhaps receives less attention is for the management of crop toxins, such as aflatoxins, that are harmful to humans.

Aflatoxins in grain crops – harmful to crops, people and animals

Aspergillus flavus is a fungus that infects cereal and staple crops, such as maize, sorghum, and groundnut. It is present mainly in humid and hot regions of the world. It infects crops before and after harvest.

Some strains of A. flavus secrete aflatoxins, highly toxic compounds that contaminate human food supplies. The toxins can cause serious health problems like malnutrition and cancer. They can even induce death if they are consumed at high levels.

In addition to endangering people’s health, aflatoxins also limit the trade of food products. The presence of aflatoxins at a certain amount might prevent growers from accessing some markets.

Aflatoxins can also be deadly for cattle, which induces more economic losses. If not fatal, the toxins accumulate in the food chain. For example, milk from animals fed with contaminated food contains aflatoxins.

A cob of maize with mould that secretes aflatoxins, which is toxic to humans
An example of a toxic Aspergillus flavus mould on a maize cob © Gary Munkvold via Bugwood.org (CC BY 3.0 US)

How does a fungal biopesticide reduce aflatoxins?

Numerous countries have adopted a particular biopesticide to control aflatoxins. Surprisingly, it is based on the toxic fungus that produces the aflatoxins itself. However, the biopesticide developed contains harmless strains of A. flavus. They are called atoxigenic strains.

Usually, the biopesticide created contains strains that are native to the country in which they are developed. Each country therefore develops its own product.

The atoxigenic strains do not secrete toxins and outcompete the toxic strains. This means that harmless strains establish on crops before the toxic strains.

Efficacy of the fungal biopesticide and benefits

The biopesticide reduces pre-harvest plant contamination by up to 90%. In some cases, aflatoxins are lowered to almost non-existent levels. As a result, the content of toxins in food and feed decreases to safe levels. The biopesticide generally prevents toxin secretion even during storage. Exposure to aflatoxins is greatly reduced, avoiding health issues in humans and cattle.

Maize cobs being sold in a street market
Maize cobs sold in a street market © Creative Commons

In addition, the harmless strains remain in the soil for an extended period. They can still bring the aflatoxins to low levels and reduce the need for frequent applications.

In the long run, using atoxigenic A. flavus can help growers to access more international markets. In this way, growers can increase their income. It is also beneficial for consumers who save on healthcare costs.

Application of this biopesticide is currently one of the most efficient ways to lower aflatoxins in food products. This biocontrol agent is used worldwide, from North America to Africa.

More info 

  1. This video demonstrates CABI working with the USDA and local maize growers to test and register a native biocontrol product, locally termed as AflaPakTM, for Pakistan.
  1. For more successful stories of biocontrol, visit the International Biocontrol Manufacturers Association (IBMA) website.

Search the CABI BioProtection Portal for registered biopesticides in your country

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