Ochratoxin A management in vineyards by Lobesia botrana biocontrol

Abstract

Grape berries attacked by Lobesia botrana larvae are more easily infected by Aspergillus section Nigri (black aspergilli) ochratoxigenic species. Two-year field trials were carried out in Apulia (Italy) to evaluate a bioinsecticide control strategy against L. botrana and the indirect effect on reducing ochratoxin A (OTA) contamination in vineyards. A commercial Bacillus thuringiensis formulate and an experimental Beauveria bassiana (ITEM-1559) formulate were tested in two vineyards cultivated with the same grape variety, Negroamaro, but with two different training systems (espalier and little-arbor techniques). In both years and training systems the treatments by B. bassiana ITEM-1559 significantly controlled L. botrana larvae attacks with effectiveness similar to B. thuringensis (more than 20%). A significant reduction of OTA concentrations (up to 80% compared to untreated controls) was observed only in the first year in both training systems, when the metereological parameters prior to harvest were more favorable to the insect attack. Results of field trials showed that B. bassiana ITEM-1559 is a valid bioinsecticide against L. botrana and that grape moth biocontrol is a strategy to reduce OTA contamination in vineyard in seasons with heavy natural infestation.

Figure 1

Lobesia botrana larva mortality in bioassays with different fungal formulates. Each bar shows the mean value with the standard deviation for 3 replicates. * tested fungal cultures: ITEM 2324—Beauveria brongnartii; ITEM 1786—Paecilomyces fumosoroseum; ITEM 1788—B. bassiana; ITEM 1784—B. brongnartii; ITEM 1399—Fusarium subglutinans; ITEM 1398—F. semitectum; ITEM 1599—B. bassiana; ITEM 1545—B. brongnartii; ITEM 1237—Verticillium spp; ITEM 1542—B. bassiana; ITEM 2013—F. verticillioides; Ctrl—control.

Figure 2

Incidence of diseased bunches and Ochratoxin A (OTA) content in four different treatments on the Negroamaro grape variety harvested with (a) espalier and (b) little-arbor training systems in 2004. Each bar represents the mean percentage of diseased bunches and the OTA level for each treatment. ANOVA on incidence of diseased bunches: field 1: F_(3,12) = 22.52, p < 0.001; field 2: F_(3,12) = 8.44, p < 0.01. ANOVA on OTA level: field 1: F_(3,12) = 20.35, p < 0.001; field 2: F_(3,12) = 19.17, p < 0.01. Mean values with the same letter were not significantly different (Duncan test, p ≤ 0.05).

Figure 3

Incidence of diseased bunches and OTA content in four different treatments on the Negroamaro grape variety harvested with (a) espalier and (b) little-arbor training systems in 2005. Each bar represents the mean percentage of diseased bunches and the OTA level for each treatment. ANOVA on incidence of diseased bunches: field 1: F_(2,9) = 28.40, p < 0.001; field 2: F_(2,9) = 21.07, p < 0.01. ANOVA on OTA level: field 1: F_(2,9) = 1.39, p > 0.05; field 2: F_(2,9) = 1.19, p > 0.05. Mean values with the same letter were not significantly different (Duncan test, p ≤ 0.05).

Figure 4

Captures of Lobesia botrana adults by pheromone traps in two-year experimental fields for biocontrol trials on the Negroamaro grape variety harvested with (a) espalier and (b) little-arbor training systems in 2004 and 2005.