Separate and combined applications of nontoxigenic Aspergillus flavus and A. parasiticus for biocontrol
of aflatoxin in peanuts |
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Authors: | Joe W Dorner Bruce W Horn |
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Institution: | (1) USDA, ARS, National Peanut Research Laboratory, 1011 Forrester Dr., SE, PO Box 509, Dawson, GA 39842, USA |
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Abstract: | A 2-year study was carried out to determine the effect of applying nontoxigenic strains of Aspergillus flavus and A. parasiticus to soil separately and in combination on preharvest aflatoxin contamination of peanuts. A naturally occurring, nontoxigenic
strain of A. flavus and a UV-induced mutant of A. parasiticus were applied to peanut soils during the middle of each of two growing seasons using a formulation of conidia-coated hulled
barley. In addition to an untreated control, treatments included soil inoculated with nontoxigenic A. flavus only, soil inoculated with nontoxigenic A. parasiticus only, and soil inoculated with a mixture of the two nontoxigenic strains. Plants were exposed to late-season drought conditions
that were optimal for aflatoxin contamination. Results from year one showed that significant displacement (70%) of toxigenic
A. flavus occurred only in peanuts from plots treated with nontoxigenic A. flavus alone; however, displacement did not result in a statistically significant reduction in the mean aflatoxin concentration
in peanuts. In year two, soils were re-inoculated as in year one and all treatments resulted in significant reductions in
aflatoxin, averaging 91.6%. Regression analyses showed strong correlations between the presence of nontoxigenic strains in
peanuts and aflatoxin reduction. It is concluded that treatment with the nontoxigenic A. flavus strain alone is more effective than the A. parasiticus strain alone and equally as effective as the mixture.
The U.S. Government’s right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged. |
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Keywords: | Arachis hypogaea Aspergillus flavus Aspergillus parasiticus Biological control Groundnut |
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