Influence of Planococcus ficus on the mycoflora and Aspergillus section Nigri and ochratoxin A incidence in vineyards from Argentina

CHIOTTA, M.L.; PONSONE L.; COMBINA M.; TORRES A.; CHULZE, S.

Viena, Austria

Conferencia; Conference International Society for Mycotoxicology (ISM).; 2009

Vine mealybug, Planococcus ficus (Signoret) is a key pest in vineyards of many grape-growing areas from Mendoza Province, Argentina. Grapes are susceptible to this insect attack, which can cause damages in berries and could be vector of toxigenic fungi. Aspergillus bunch rots, is a berry pre-harvest deterioration caused by species belonging to Aspergillus section Nigri. This fungal species are also responsible for ochratoxin A contamination. Black aspergilli incidence and ochratoxin A contamination could be favoured by berries damage caused by insects. The aim of this study was to evaluate the effect of Planococcus ficus grapes infection on Aspergillus section Nigri contamination and ochratoxin A occurrence. At 2007 and 2009 harvest season, three grape varieties (Merlot, Malbec and Cabernet) in two categories of grape samples: undamaged and damaged berries were evaluated. During 2007 harvest season, the fungal genus with highest incidence was Alternaria spp. (63%), followed by Aspergillus spp. and Penicillium spp. isolated in a frequency of 18% and 13%, respectively. Clodosporium spp., Fusarium spp., Trichoderma spp., Rhizopus spp. and yeasts were isolated at percentages of less than 10%. In harvest season 2009, the grape samples show high yeast contamination (10 -100%) and only the infection percentage of Alternaria (55%) and Aspergillus (56%) were relevant in Cabernet Sauvignon variety. Regardless of the grape variety and the harvest season evaluated, damage berries showed the highest levels of contamination with Aspergillus section Nigri (P<0.05). Merlot variety showed the high levels of black aspergilli contamination during 2007 (53.5% and 20% in damage and undamaged grape, respectively) while Cabernet Sauvignon presented the highest incidence during 2009 (56% and 14% in damage and undamaged grape, respectively). The mean ochratoxin A concentration in damaged berries samples was significantly higher than the undamaged ones (P<0.001). The highest OTA contamination levels were detected during 2007, ranging from 0.5 to 140.2 ng g-1. Cabernet Sauvignon variety showed highest levels of toxin detected (mean: 50.1% and 3.4%, in 2007 and 2009 respectively). These results showed the potential risk of OTA contamination in vineyard infected with Planococus ficus and the need of to implement insect control at pre-harvest stage.