Assessing the toxicity of pesticides on natural soil and plant assemblages of AMF

Pesticide usage is regulated by the international standardized methods, to assess their toxicological effects on the environment. However, how these compounds affect the off-target soil microorganisms, remains elusive, due to the no-well-defined regulatory-tiered scheme for assessing the soil microbial toxicity of pesticides. The main aim of this work is to develop and implement advanced experimental lab and field tests to assess the toxicity of pesticides on natural soil assemblages of Arbuscular mycorrhizal fungi (AMF), which will result in designing guidelines and protocols for the further usage.

Fig. 1. Microcosm experiment, where the effect of 3 pesticides (1x and 10x recommended doses) on natural soil assemblages of AMF and introduced AMF inoculum was studied. The main aim was to understand if the introduced AMF inoculum helps to improve the plant growth parameters when the plant/ soil are exposed to the pesticide, and the role of the AMF inoculum in the dissipation/ degradation process of the pesticides.

In order to achieve these, it is important to be able to detect the functionally important members of the AMF community, which will be performed by using second and third generation sequencing approaches. With this tool, it will be possible to define effects of pesticides on the function and diversity of natural soil assemblages of AMF. Understanding of the potential toxicity mechanisms of pesticides, as well the potential role of AMF in the pesticide dissipation process is also part of this project.

Fig. 2. Microcosm experiment, in collaboration with ESR8, where we have tested how 6 pesticides (3 synthetic and 3 bio) affect the natural soil microbial community when applied at 1x and 10x recommended doses. From the preliminary results, it has been shown that the biopesticides have a positive effect on plant growth parameters, and their half-lives are shorter compared to the synthetic ones.

Collaboration with ESR8, has already been performed (microcosm environment), where the main aim was to understand if synthetic and bio pesticides have different effects on the natural soil microbial community. With the ESR3, a field experiment is planned to be performed, where the same pesticides and a plant will be used for the assessment of differences in the response of the natural soil microbial community from 2 different soil types.

Fig. 2. Multiplication of different AMF strains, in so-called “Trap cultures”. Here a simplified scheme of the process is described. Purpose of this work was to maintain the AMF strains (kindly provided by The CEnter of Study on AM Monoxenics of the Microbiology unit of the "Université catholique de Louvain", Belgium) and afterwards use them in the scope of the PhD work.