Occurrence and distribution of aflatoxin contamination in groundnuts (Arachis hypogaea L) and population density of Aflatoxigenic Aspergilli in Malawi

Monyo, E S and Njoroge, S M C and Coe, R and Osiru, M and Madinda, F and Waliyar, F and Thakur, R P and Chilunjika, T and Anitha, S (2012) Occurrence and distribution of aflatoxin contamination in groundnuts (Arachis hypogaea L) and population density of Aflatoxigenic Aspergilli in Malawi. Crop Protection, 42. pp. 149-155. ISSN 0261-2194

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Abstract

Groundnut (Arachis hypogaea L.) is susceptible to pre- and post-harvest infections by Aspergillus spp. Aflatoxin B1 (AFB1), is the contaminant produced by the fungus in infected grains posing a threat to human and animal health. This paper reports of a study undertaken in Malawi to determine the occurrence and distribution of Aflatoxigenic Aspergilli in the soil and AFB1 contamination in groundnuts. A total of 1397 groundnut samples collected from farm homesteads, local markets, warehouses and shops in 2008 and 2009 were analyzed for AFB1 contamination using the enzyme linked immunosorbent assay (ELISA), and A. Aspergilli population densities in 1053 soil samples collected from the same sites were estimated using serial dilutions plated on A. Aspergilli medium. Farmer socio-economic profile information was also collected to determine relationships to AFB1 contamination. The results revealed 46% and 23% of the total samples, from 2008 to 2009, respectively, had AFB1 contamination levels greater than 4 ppb, and those above 20 ppb were 21% for 2008 and 8% for 2009, respectively. Fitted smooth curve relationships show that there is a clear increase in the chance of groundnut contamination when the population density of A. Aspergilli in the soil increased beyond 3000 (log (cfu) > 8). The measured level of A. Aspergilli in soil varied by location, as well as ecologies within location. Low-altitude ecologies, which were warmer and experienced low precipitation levels, had the highest densities of A. Aspergilli, whereas cooler high-altitude ecologies had the lowest density of these fungi. Similarly high AFB1 contamination, was recorded across the country with 11–28% of all samples collected from the warm low to mid-altitude ecologies recording contamination ≥20 ppb and low contamination (2–10% of samples) in the mid to high altitude cool ecologies. From a crop management perspective, this study also suggests that both less experienced and older farmers were more likely to produce groundnuts contaminated with aflatoxin. These findings have implications in the design of intervention strategies to avoid short- and long-term human health effects from aflatoxin exposure.

Item Type: Article
Divisions: UNSPECIFIED
CRPS: UNSPECIFIED
Uncontrolled Keywords: AFB1; AFB1 contamination; Aflatoxigenic Aspergilli; Aspergillus spp.; Pre- and post-harvest infection; Colony forming units; Groundnut (Arachis hypogaea L.); Malawi
Subjects: Mandate crops > Groundnut
Others > Plant Pathology
Others > Plant Virology
Depositing User: Mr Sanat Kumar Behera
Date Deposited: 11 Oct 2012 05:09
Last Modified: 14 Sep 2013 09:32
URI: http://oar.icrisat.org/id/eprint/6182
Official URL: http://dx.doi.org/10.1016/j.cropro.2012.07.004
Projects: UNSPECIFIED
Funders: McKnight Foundation-Collaborative Crops Research Program (CCRP)
Acknowledgement: The team acknowledges the collaboration of key individual and Government Departments in Malawi and institutional support from ICRISAT. It is for this reason the team is indebted to the District Agricultural Development Officers and farmers from the participating 11 districts and Dr Andrew Daudi former Principal Secretary Agriculture for encouragement. The team is also indebted to Dr Moses Siambi for logistical support which facilitated the completion of the study. This study was supported by the McKnight Foundation, under the Collaborative Crops Research Program (CCRP).
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