Mycotoxins in Flanders' Fields: Occurrence and Correlations with Fusarium Species in Whole-Plant Harvested Maize

Abstract

Mycotoxins are well-known contaminants of several food- and feedstuffs, including silage maize for dairy cattle. Climate change and year-to-year variations in climatic conditions may cause a shift in the fungal populations infecting maize, and therefore alter the mycotoxin load. In this research, 257 maize samples were taken from fields across Flanders, Belgium, over the course of three years (2016-2018) and analyzed for 22 different mycotoxins using a multi-mycotoxin liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. DNA of Fusarium graminearum, F. culmorum and F. verticillioides was quantified using the quantitative polymerase chain reaction (qPCR). Multi-mycotoxin contamination occurred frequently, with 47% of samples containing five or more mycotoxins. Nivalenol (NIV) was the most prevalent mycotoxin, being present in 99% of the samples, followed by deoxynivalenol (DON) in 86% and zearalenone (ZEN) in 50% of the samples. Fumonisins (FUMs) were found in only 2% of the samples in the wet, cold year of 2016, but in 61% in the extremely hot and dry year of 2018. Positive correlations were found between DON and NIV and between F. graminearum and F. culmorum, among others. FUM concentrations were not correlated with any other mycotoxin, nor with any Fusarium sp., except F. verticillioides. These results show that changing weather conditions can influence fungal populations and the corresponding mycotoxin contamination of maize significantly, and that multi-mycotoxin contamination increases the risk of mycotoxicosis in dairy cattle.

Keywords: Fusarium; Maize; forage; fumonisins; maize ear rot; monitoring; mycotoxins; nivalenol; silage.

Figure A1

Heat map based on the pairwise Pearson correlation coefficients between the measured mycotoxin concentrations in 2016. A darker blue color indicates a stronger negative correlation, a darker red color indicates a stronger positive correlation. Significant correlations are indicated with asterisks (* p < 0.05, *** p < 0.01). DON+ = the sum of the concentrations of DON, 3-ADON and 15-ADON.

Figure A2

Heat map based on the pairwise Pearson correlation coefficients between the measured mycotoxin concentrations in 2017. A darker blue color indicates a stronger negative correlation, a darker red color indicates a stronger positive correlation. Significant correlations are indicated with asterisks (* p < 0.05, *** p < 0.01). DON+ = the sum of the concentrations of DON, 3-ADON and 15-ADON.

Figure A3

Heat map based on the pairwise Pearson correlation coefficients between the measured mycotoxin concentrations in 2018. A darker blue color indicates a stronger negative correlation, a darker red color indicates a stronger positive correlation. Significant correlations are indicated with asterisks (* p < 0.05, *** p < 0.01). DON+ = the sum of the concentrations of DON, 3-ADON and 15-ADON.

Figure A4

Heat map based on the pairwise Pearson correlation coefficients between the measured mycotoxin concentrations in 2017-2018, with the exclusion of 3 outliers. A darker blue color indicates a stronger negative correlation, a darker red color indicates a stronger positive correlation. Significant correlations are indicated with asterisks (* p < 0.05, *** p < 0.01). DON+ = the sum of the concentrations of DON, 3-ADON and 15-ADON.

Figure A5

Heat map based on the pairwise Pearson correlation coefficients between measured mycotoxin concentrations and DNA of F. graminearum, F. verticillioides and F. culmorum in 2017. A darker blue color indicates a stronger negative correlation, a darker red color indicates a stronger positive correlation. Significant correlations are indicated with asterisks (* p < 0.05, *** p < 0.01). DON+ = the sum of the concentrations of DON, 3-ADON and 15-ADON. FUM = the sum of the concentrations of FB1, FB2 and FB3.

Figure A6

Heat map based on the pairwise Pearson correlation coefficients between measured mycotoxin concentrations and DNA of F. graminearum, F. verticillioides and F. culmorum in 2018. A darker blue color indicates a stronger negative correlation, a darker red color indicates a stronger positive correlation. Significant correlations are indicated with asterisks (* p < 0.05, *** p < 0.01). DON+ = the sum of the concentrations of DON, 3-ADON and 15-ADON. FUM = the sum of the concentrations of FB1, FB2 and FB3.

Figure 1

Location of the 106 dairy farms and 17 weather stations in Flanders, Belgium.

Figure 2

The relative number of maize samples contaminated with a certain number of different mycotoxins for 2016, 2017 and 2018.

Figure 3

Heat map based on the pairwise Pearson correlation coefficients between the measured mycotoxin concentrations from 2016–2018. A darker blue color indicates a stronger negative correlation, a darker red color indicates a stronger positive correlation. Significant correlations are indicated with asterisks (* p < 0.05, *** p < 0.01). DON+ = the sum of the concentrations of DON, 3-ADON and 15-ADON. FUM = the sum of the concentrations of FB1, FB2 and FB3.

Figure 4

Incidence of F. graminearum, F. verticillioides, F. culmorum and Fusarium spp. in general, in samples of harvested maize in 2017, 2018 and in both years combined.

Figure 5

Heat map based on the pairwise Pearson correlation coefficients between measured mycotoxin concentrations and DNA of F. graminearum, F. verticillioides and F. culmorum from 2017–2018. A darker blue color indicates a stronger negative correlation, a darker red color indicates a stronger positive correlation. Significant correlations are indicated with asterisks (* p < 0.05, *** p < 0.01). DON+ = the sum of the concentrations of DON, 3-ADON and 15-ADON. FUM = the sum of the concentrations of FB1, FB2 and FB3.