Infection of Termite Scarified Groundnuts by Aspergillus Section flavi and Contamination by Aflatoxin

Abstract

Groundnuts are invaded by members of Aspergillus section Flavi(Aspergillus flavus, A. parasiticus, A. tamari, A. caelatus and A.alliaceus) of which A. flavus and A. parasiticus sequester carcinogenic toxins known as aflatoxins. These aflatoxins producing fungi infect groundnut pods/seeds during maturation with the highest fungal population and aflatoxin contamination occurring in damaged seeds. One hundred and fifty six groundnut samples comprising termite scarified and uncompromised pods were collected from farmer‟s fields in Zamfara, Katsina and Kano states, Nigeria. Groundnut seeds were found to be infected by A. flavus as well as A. niger. The highest incidences of A.flavus and A. niger were seen to occur in damaged seeds obtained from Kano (47%/10%) and Katsina (10%/9%) states. The undamaged seeds had a lower incidence of the fungi in Kano (38%/0%) and Katsina(7%/7%) Aflatoxin B1 concentrations between the scarified and undamaged seeds were statistically insignificant. Mean aflatoxin B1concentration in scarified seeds across the three states was higher (19.65μg/kg) than in the undamaged seeds (4.21 μg/kg). Ninety two per cent of samples had aflatoxin B1 concentrations below the 20 μg/kg regulatory limit in Nigeria. The colonization of groundnuts by soil inhabiting aflatoxigenic A. flavus is enhanced by termite damage to the pods. This leads to an increase in the synthesis and concentration of the carcinogenic aflatoxin B1 in infected seeds.