Evaluation of potential biocontrol agent for aflatoxin in Argentinean peanuts

ALANIZ ZANON M.S; CHIOTTA, M.L; GIAJ-MERLERA, G.; BARROS, G.G; CHULZE, S

Mendoza

Congreso; Strategies to reduce the impact of mycotoxins in Latin America in a global context; 2011

UNRC, ISM, Mycored

Biocontrol by competitive exclusion has been developed as the most promising means of controlling aflatoxin in peanuts. The aim of this work was to evaluate an A. flavus strain as a potential biocontrol agent to reduce aflatoxin production in peanuts under field and storage conditions in Argentina. The competitive strain used was a atoxigenic A. flavus (AFCHG2) naturally occurring in soil from Córdoba Province, Argentina. The inoculum was produced through solid-state fermentation on long grain rice and applied at a rate of 50 kg inoculum/ha. The evolution of the biocontrol agent was followed using the shift of the atoxigenic/toxigenic ratio and VCGs analysis between treated and control plots on pod maturation stage. The first year of study 2009/10 demonstrated that the atoxigenic strain applied remained on the soil, competed with mycoflora resident and was the dominant strain at ripening of the pods. The absence of conducive conditions for aflatoxin production, made impossible to assess the biocontrol agent effectiveness in reducing the levels of aflatoxin in the grain under field conditions. However, it was proved its protective effect in storage under conducive conditions. During the 2010/11 harvest season, the effectiveness of the atoxigenic strain applied at preharvest stage was demonstrated under conducive conditions for aflatoxin production by the coverage of the crop during pods ripening. Relative levels of aflatoxin B1 reduction ranged from 64% to 75%. This is the first study using the exclusion competitive strategy to reduce the risk of aflatoxin contamination in peanuts done in Argentina using a biopesticide based on native A. flavus strain.