Bio-competitive exclusion: efficacy of non-aflatoxigenic Aspergillus section Flavi-L morphotypes in control of aflatoxigenic Aspergillus flavus in groundnuts (Arachis hypogaea L.)

Background The biological control mechanism of Aspergillus flavus (aflatoxigenic) strains in groundnuts with atoxigenic strains from the same species through competitive exclusion employed the use of endemic and well-adapted strains within the agro-ecological zones of Zimbabwe. The selected elite non-aflatoxigenic isolates of A. flavus native to Zimbabwe were evaluated for their capability to reduce aflatoxin contamination in groundnuts under laboratory conditions. Results Average reduction percentages in aflatoxin B concentration for the 2019 and 2020 set of experiments ranged from 91.6 +/- 3.4 to 95.8 +/- 3.1% and 90.29 +/- 3.6% to 95.29 +/- 4.1%, respectively. Levels of aflatoxin in the co-inoculation research experiments administered were significantly reduced in all the experimental units carried out. Treatment efficiencies of the tested isolates in this study at 4:1 and 2:1 ranged from 1.20 to 2.52 and from 1.02 to 1.21, respectively. The efficacy of the tested non-aflatoxigenic strains against the aflatoxigenic strain native to Zimbabwe (ZMW 0127) indicates that the non-aflatoxigenic isolates of A. flavus. have sound practical applications against vast communities of aflatoxin-producing fungi across all the agro-ecological zones in Zimbabwe. Conclusion The recognized non-aflatoxigenic isolates will be of an incentive as dynamic active ingredients in biocontrol formulations for the decrease in aflatoxins in groundnuts grown in Zimbabwe.