Aflatoxins are toxic and carcinogenic mycotoxins found in a range of agricultural products, particularly cereals and nuts. Of especial concern are potentially high levels of these mycotoxins in maize and peanuts, which form part of staple diets in many parts of Asia.
The major fungus producing aflatoxins is Aspergillus flavus. However, another fungus,Aspergillus parasiticus and a few other minor species of Aspergillus can also produce these toxins.
Aflatoxins in crops:
All cereal crops can contain aflatoxins. Intensive cropping practices and decreased genetic diversity in cereal crops probably contribute to increased preharvest infections of commodities with fungi that produce aflatoxins. Preharvest contamination of crops with aflatoxins occurs in the temperate and tropical regions.
The seeds in growth-stressed plants are the most susceptible to fungal invasion and aflatoxin production. Postharvest contamination occurs worldwide when conditions in the storage unit exist for the growth of Aflatoxigenic fungi. Aflatoxigenic fungi can grow in feedlot manure.
Insects spread the spores of aflatoxigenic fungi to plants and the fungi colonize areas of insect damage. The flower and silk in corn can be portals of entry for species of Aspergillus.
Insect damage, timing of irrigation or rain, relative humidity around the bolls, stage of maturity and variety of cotton can be factors in causing preharvest contamination of cottonseed with aflatoxins.