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IInnnnoovvaattiioonn BBrriieeff
No. 6, October 2010
CGIAR Systemwide Program
on Integrated Pest
Management (SP-IPM) is a
global partnership that draws
together the diverse IPM
research, knowledge, and
expertise of the international
agricultural research centers
and their partners to build
synergies in research outcomes
and impacts, and to respond
more effectively to the needs
of farmers in developing
countries.
SP-IPM Technical Innovation
Briefs present, in short, IPM
research findings and
innovations for the
management of pests, diseases,
and weeds in agricultural
production.
This and other IPM Briefs are
available from
www.spipm.cgiar.org
Aflatoxins – the invisible threat in foods and feeds
Ranajit Bandyopadhyay
The Facts
Aflatoxins are highly toxic fungal metabolites causing suppression of the immune system, growth retardation,
liver cancer, and even death in humans and domestic animals. Aflatoxins also affect the rate of recovery from
protein malnutrition, Kwashiorkor (Hendrickse, 1984), and exert severe nutritional interference, including in
protein synthesis, modification of micronutrients, and uptake of vitamin A and D. Exposure in animals reduces
milk and egg yields. The contamination of milk and meat is passed on to humans.
Aflatoxins affect cereals, oilseeds, spices, tree nuts, milk, meat, and dried fruits.
Maize and groundnut are major sources of human exposure because of their
higher susceptibility to contamination and frequent consumption. The toxins are
most prevalent within developing countries in tropical regions and the problem is
expected to be further exacerbated by climate change (Cotty and Jaime-Garcia,
2007).
The aflatoxin-producing fungi (Aspergillus spp.) come in contact with crops in
the field during crop development. They stay with the crops until their final use.
If the environment where crops are stored is humid and warm, the fungi, which
moved into storage with the crops, can proliferate and produce more aflatoxins.
Aspergillus communities in different regions differ in their aflatoxin-producing
ability. In some locations, they produce large concentrations; in others, they
produce relatively lower amounts.
Green growth of Aspergillus
The high incidence of aflatoxin throughout Sub-Saharan Africa aggravates an fungus on maize cob. – IITA
already food insecure situation. Agricultural productivity is hampered by contamination, compromising food
availability, access, and utilization. Unless aflatoxins in crops and livestock are effectively managed, marketable
production and food safety cannot improve. Thus, the economic benefits of increased trade cannot be achieved.
Aflatoxins cost farmers and countries hundreds of millions of dollars annually. These losses have caused crops
to be moved out of regions, companies to go bankrupt, and entire agricultural communities to lose stability.
Additionally, effective control must be achieved before many development activities aimed at achieving food
security can be implemented, such as local food procurement strategies complementing food aid and school
feeding programs, and ready-to-use therapeutic foods.
Aflatoxin Management
Contamination occurs before and after crop maturity. To ensure the greatest crop value and the lowest exposure
of humans to aflatoxins, management must extend from field to fork. Currently, contamination is prevented by a
combination of tools, such as post-harvest drying (where cost-effective), proper storage, shelling, de-hulling,
sorting, early harvest, using regionally adjusted planting dates, and insect control. Pre-harvest management is
unreliable. In 1989, farmers in the USA formed the Multi-crop Aflatoxin Working Group and joined with the US
Department of Agriculture to increase research on aflatoxin management with an emphasis on breeding and
transgenic crops. When the program was discontinued in 2008, commercially useful resistant crops still had not
been developed, but there was an unexpected advance.
Biocontrol – a novel approach
A biological control technique greatly reduced aflatoxins in all the susceptible crops in a cost-effective manner
and over a broad geographic area. Native strains of A. flavus that do not produce aflatoxins (“atoxigenic strains”)
are used to competitively exclude aflatoxin-producing strains from the crop environment.