STUDIES ON ASPERGILLUS PARASITICUS IN THE PEANUT AGROECOSYSTEM IN ARGENTINA

BARROS, G.; CHIOTTA, L.; TORRES, A.; CHULZE, S.

Bethesda, Maryland, USA

Simposio; XI International IUPAC Symposium on Mycotoxins and Phycotoxins; 2004

Previous studies showed that Aspergillus flavus and A. parasiticus are the main species among the soil fungal population in the peanut-growing region in Argentina. The aim of present study was to evalute ecophysiological characteristics (sclerotia and aflatoxin production) of A. parasiticus populations isolated from soil, debris and peanut seeds. Aspergillus species were identificated following Pitt and Hocking (1997). Sclerotia production was determined according to Cotty (1989) and the aflatoxin production was determined according to Geisen et al. (1996). Among the A. parasiticus strains (n=147) isolated from soil, a 90% produced B- type aflatoxins ranging from 0.99 to 148.8 mg ml-1 and G-type aflatoxins ranging from 0.27 to 163.6 mg ml-1. From 25 A. parasiticus strains isolated from debris samples, 75% produced B- type aflatoxins (range, 9.8 to 403.3 mg ml-1) and G- type aflatoxins ranging from 6.0 to 367.0 mg ml-1. 20% of peanut seeds samples were infected by A. parasitcus. Out of 35 strains, 98% of them produced B aflatoxins (range, 1.0 to 160.0 mg ml-1) and G aflatoxins ranging from 0.4 to 170.6 mg ml-1. Out of 207 A. parasiticus strains only 25% produced sclerotia. The low percentage of sclerotia-producing strains could indicate that the strategy of this species to survive in the soil is forming mycelium and/or spores.