Effectiveness of Plant Extracts for Biocontrol of Aspergillus flavus on Stored Groundnut in North East Nigeria

Aflatoxin contamination of stored groundnut caused by Aspergillus flavus is a serious public health and food trade constraint in North East Nigeria. Plant-derived essential oils and extracts offer a potentially accessible and low-cost biocontrol option for aflatoxin management in smallholder storage systems, yet their efficacy under North East Nigerian storage conditions requires empirical validation. This study evaluated the antifungal activity and aflatoxin suppression capacity of extracts from five plants, including Ocimum gratissimum, Azadirachta indica, Eucalyptus camaldulensis, Cymbopogon nardus, and Lippia multiflora, against A. flavus on groundnut under controlled and field storage conditions across three districts of Gombe State. In vitro antifungal assays on potato dextrose agar established minimum inhibitory concentrations. Storage trials applied extracts as grain coatings at two concentrations, with aflatoxin B1 levels measured by high-performance liquid chromatography at 0, 3, and 6 months. O. gratissimum extract at 1.5 percent concentration achieved 78 percent inhibition of A. flavus growth in vitro and reduced aflatoxin B1 accumulation below 5 micrograms per kilogram in coated groundnut samples after six months storage, compared to 42 micrograms per kilogram in untreated controls. A. indica extract showed moderate antifungal activity but significantly lower aflatoxin suppression, suggesting multiple mechanisms of action for O. gratissimum. No significant phytotoxicity to groundnut seed germination capacity was observed at applied concentrations. The study recommends O. gratissimum extract as a viable, low-cost aflatoxin management supplement for smallholder groundnut storage in North East Nigeria. Keywords: Aspergillus flavus, aflatoxin, plant extracts, groundnut storage, North East Nigeria.