Aflatoxin contamination of pearl millet during field and storage conditions with reference to stage of grain maturation and insect damage

Aflatoxin contamination in five varieties of pearl millet (ICMH-451, ICMP-50I, ICTP-8203, WCC-75 and ICMV-155) was studied from field and storage conditions in three districts of Andhra Pradesh State, India and the inter-relationships between various parameters such as stage of grain maturation in the field and insect pest infestation in storage in relation to aflatoxin production were evaluated. Aflatoxin contamination was more frequent in the seed samples collected from the fields during rainy season than winter season. All major aflatoxins were isolated from one or the other varieties of pearl millet, whereas aflatoxin G₂ was not commonly observed in the seed samples collected during winter. Among all the varieties tested, ICMH-451 was vulnerable to aflatoxin contamination whereas ICMV-155 was the least susceptible variety. The higher amount of aflatoxins was observed in the matured seed samples followed by pre-matured and milky stage. Among all the toxins reported in the field, aflatoxin B₁ was found in higher concentration (185 (μg/kg) followed by B₂ (105 μg/kg). The four major types of aflatoxins with higher levels (35, 40, 140, 190 μg/kg of G₁, G₂, B₂, B₁ were reported in the rainy season seed samples after six months of storage, whereas aflatoxin G₁ was not observed in any variety of stored seed sample from winter. Statistical analysis revealed that the aflatoxin incidence in relation to different parameters studied was significantly different for each factor. The relationship between aflatoxin contamination and insect damaged-grain clearly indicated that the seed samples with 16-40% of insect damage contained higher amounts of aflatoxins (758 μg/kg). Presented at the 29^th Mykotoxin-Workshop, Fellbach, Germany, May 14–16, 2007