Mode of action of pesticides on aflatoxin biosynthesis and oxidase system activity

Effect of in vitro glyphosate on Fusarium spp. growth and disease severity in maize

BACKGROUND

Glyphosate (GP) is one of the main pesticides used for maize production. Fusarium sp. is a fungal genus with several phytopathogenic species and toxigenic features. In this study, the culturable soil mycota was evaluated using the surface-spray method. The effect of GP on the growth parameters (growth rate and lag phase) of Fusarium spp. was also tested on solid media conditioned with different water activities. Finally, the GP effect on disease severity caused by Fusarium sp. in maize seedlings was studied.

RESULTS

The results showed that Fusarium species are frequently isolated from GP-exposed soils. The GP concentrations tested had a significant effect on F. graminearum, F. verticillioides and F. oxysporum growth parameters on solid media. The pathogenicity tests showed that the disease severity of the maize seedlings significantly increased with increasing GP concentrations.

CONCLUSIONS

This study showed that Fusarium species are frequently isolated from pesticide-exposed soils and the GP concentrations tested had a significant effect both on growth parameters and disease severity in maize. This study provides an approach to the effect of GP on Fusarium sp. growth and pathogenicity that reinforces the importance of evaluating all the factors that could affect feed and food production. © 2019 Society of Chemical Industry.

Influence of herbicide glyphosate on growth and aflatoxin B1 production by Aspergillus section Flavi strains isolated from soil on in vitro assay

The effect of six glyphosate concentrations on growth rate and aflatoxin B1 (AFB1) production by Aspergillus section Flavi strains under different water activity (aW) on maize-based medium was investigated. In general, the lag phase decreased as glyphosate concentration increased and all the strains showed the same behavior at the different conditions tested. The glyphosate increased significantly the growth of all Aspergillus section Flavi strains in different percentages with respect to control depending on pesticide concentration. At 5.0 and 10 mM this fact was more evident; however significant differences between both concentrations were not observed in most strains. Aflatoxin B1 production did not show noticeable differences among different pesticide concentrations assayed at all aW in both strains. This study has shown that these Aspergillus flavus and A. parasiticus strains are able to grow effectively and produce aflatoxins in high nutrient status media over a range of glyphosate concentrations under different water activity conditions.

Comparison of contaminant and residue levels in organic and conventional milk and meat products from Northern Italy

Due to the growing interest in organic products, a comparison between the chemical safety of organic and conventional products was undertaken. Milk and meat were the products chosen for study. The parameters evaluated to assess chemical safety were organochlorine pesticides, polychlorinated biphenyls (PCBs), lead, cadmium and mycotoxin contamination. Pesticides and PCBs residues in both organic and conventional milk and meat were lower than legal limits. Lead and cadmium residues were very low and did not differ between organic and conventional products. However, aflatoxin M1 contamination in some but not all samples of organic milk was significantly higher than those of conventional milk, although factors other than organic production might be implicated.