Alexandra Sybertz
Dr. rer. nat.
+49 241 80-26686
Publikationen
2025
Sybertz A; Ottermanns R; Roß-Nickoll M
In: MethodsX, Bd. 14, 2025, ISSN: 2215-0161.
@article{Sybertz2025,
title = {MIXCOP–Implementation of a model to assess the time-dependent effects of mixed pesticides on a collembolan population},
author = {Alexandra Sybertz and Richard Ottermanns and Martina Roß-Nickoll},
doi = {10.1016/j.mex.2025.103403},
issn = {2215-0161},
year = {2025},
date = {2025-06-00},
urldate = {2025-06-00},
journal = {MethodsX},
volume = {14},
publisher = {Elsevier BV},
abstract = {A new simulation model has been created by merging three model approaches, including soil exposure prediction, effect estimation and a population model.
• The aim is to use the overall model to better assess the effects of pesticides on soil organisms.
• The model is called MIXCOP (pesticide MIXtures and their effects on a COllembolan Population) and simulates a population of Folsomia candida in a vertical soil column.
• MIXCOP allows to calculate a time- and movement-dependent exposure for the individual animals, as well as the resulting effects. Effects on both adult organisms and juvenile organisms are taken into account. The modular structure including the individual assumptions are explained in more detail.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A new simulation model has been created by merging three model approaches, including soil exposure prediction, effect estimation and a population model.
• The aim is to use the overall model to better assess the effects of pesticides on soil organisms.
• The model is called MIXCOP (pesticide MIXtures and their effects on a COllembolan Population) and simulates a population of Folsomia candida in a vertical soil column.
• MIXCOP allows to calculate a time- and movement-dependent exposure for the individual animals, as well as the resulting effects. Effects on both adult organisms and juvenile organisms are taken into account. The modular structure including the individual assumptions are explained in more detail.
2024
Sybertz A
Modelling of single and mixed pesticide applications and their effects on soil organisms in agricultural landscapes Promotionsarbeit
RWTH Aachen University, 2024.
@phdthesis{nokey,
title = {Modelling of single and mixed pesticide applications and their effects on soil organisms in agricultural landscapes},
author = {Alexandra Sybertz},
doi = {10.18154/RWTH-2024-07602},
year = {2024},
date = {2024-07-18},
school = {RWTH Aachen University},
abstract = {Biodiversity loss is one of the major current challenges facing humanity. This is due to various stressors such as climate change, changes in land use and the immigration of invasive species. Chemical pollution, caused by industrial production or direct application of chemicals as pesticide, is also part of this. Considering that around 58 % of the world's species live in soil, the relevance of this pollution for biodiversity is obvious. Adequate consideration of the potential effects of pesticides on soil organisms in the agricultural landscape is essential to ensure better protection of this important habitat in the future. Pesticides are currently assessed with regard to individual substances and their single application. The effects of pesticides spray sequences and their temporal relevance are not taken into account. In this research project, a model framework was developed and evaluated that assesses both the consequences of spray sequences and the effects on individual organisms and populations. Pesticide effects are considered depending on the temporal and spatial exposure. The model framework, consisting of three different models called MITAS+GUTS, MIXCOP and MITAS L, focuses on different aspects that are relevant for evaluating the effects of soil organisms. The models are based on existing ecotoxicological data that can be re-evaluated using the modelling approach. An initial data query revealed only limited availability of detailed ecotoxicological data, particularly on terrestrial organisms. Results of such tests are often published as aggregated effect endpoints, such as LC50 values. Nevertheless, sufficient ecotoxicological information was collected to be able to evaluate the model framework. The MITAS+GUTS model enables the prediction of a time-dependent effect for a single organism. It is therefore well suited for predicting the time-dependent effect of spray sequences with different pesticides for various soil organisms. This allows the effects on different organisms to be compared and more sensitive species to be detected. In this work, for example, the collembolan F. candida is identified as a more sensitive organism for an applied pesticide spray sequence compared to the earthworms, which are also considered. The sensitivity of this collembolan species was further analysed using the MIXCOP model. This MIXCOP model simulates a population of F. candida in a vertical soil column and is able to calculate a time- and movement-dependent exposure of the individual animals, as well as the resulting effect. Simulations with different pesticides and a spray sequence revealed the application time and the degradation rate of the substance to have a major impact on the population. The effect of a pesticide application scenario on the population is always considered as a deviation from a stable, uncontaminated population. The MIXCOP model indicated some strong population effects for a pesticide application, which is within the acceptable regulatory threshold for terrestrial soil organisms. Simulation of an annual application of two different pesticides for four years showed no recovery of the population until the end of the simulated period. In addition to the vertical soil consideration, the MIXCOP is also able to incorporate the temporal effect. This allows a kind of pesticide application history to be simulated for up to five years. The MITAS L model considers the horizontal distribution of pesticides in the landscape and their potential risk to soil organisms. Variable application amounts in cultivated areas are taken into account, as well as the exposure of field margins. In addition to a variable area-related risk, an average cumulative risk value can also be calculated for the entire simulation area. This allows calculation of a potential overall risk for new application methods, like in precision farming. Furthermore, this model is suitable as basis for a spatial risk assessment. This would enable calculation of a risk for various application scenarios for a landscape section consisting of arable land and field margins. This allows the ecotoxicological assessment of new application systems such as drones.Application examples are used to show that the model framework (MITAS+GUTS, MIXCOP and MITAS L) can be used for prospective and retrospective evaluation of pesticide effects in the landscape. Different spatial levels (vertical soil column & horizontal area), different organisational levels (individual organisms & population) as well as different impact calculations (risk indicator & effect) are considered within the framework. The application examples are used to identify the application limits, strength and weaknesses of the model framework. Potential for improvement and further development is identified as a result. The model framework based on MITAS+GUTS, MIXCOP and MITAS L is shown to be suitable for evaluating different pesticide application strategies. This could help to reduce chemical pollution in the agricultural landscape and its effects on soil organisms in the future.},
keywords = {},
pubstate = {published},
tppubtype = {phdthesis}
}
Biodiversity loss is one of the major current challenges facing humanity. This is due to various stressors such as climate change, changes in land use and the immigration of invasive species. Chemical pollution, caused by industrial production or direct application of chemicals as pesticide, is also part of this. Considering that around 58 % of the world's species live in soil, the relevance of this pollution for biodiversity is obvious. Adequate consideration of the potential effects of pesticides on soil organisms in the agricultural landscape is essential to ensure better protection of this important habitat in the future. Pesticides are currently assessed with regard to individual substances and their single application. The effects of pesticides spray sequences and their temporal relevance are not taken into account. In this research project, a model framework was developed and evaluated that assesses both the consequences of spray sequences and the effects on individual organisms and populations. Pesticide effects are considered depending on the temporal and spatial exposure. The model framework, consisting of three different models called MITAS+GUTS, MIXCOP and MITAS L, focuses on different aspects that are relevant for evaluating the effects of soil organisms. The models are based on existing ecotoxicological data that can be re-evaluated using the modelling approach. An initial data query revealed only limited availability of detailed ecotoxicological data, particularly on terrestrial organisms. Results of such tests are often published as aggregated effect endpoints, such as LC50 values. Nevertheless, sufficient ecotoxicological information was collected to be able to evaluate the model framework. The MITAS+GUTS model enables the prediction of a time-dependent effect for a single organism. It is therefore well suited for predicting the time-dependent effect of spray sequences with different pesticides for various soil organisms. This allows the effects on different organisms to be compared and more sensitive species to be detected. In this work, for example, the collembolan F. candida is identified as a more sensitive organism for an applied pesticide spray sequence compared to the earthworms, which are also considered. The sensitivity of this collembolan species was further analysed using the MIXCOP model. This MIXCOP model simulates a population of F. candida in a vertical soil column and is able to calculate a time- and movement-dependent exposure of the individual animals, as well as the resulting effect. Simulations with different pesticides and a spray sequence revealed the application time and the degradation rate of the substance to have a major impact on the population. The effect of a pesticide application scenario on the population is always considered as a deviation from a stable, uncontaminated population. The MIXCOP model indicated some strong population effects for a pesticide application, which is within the acceptable regulatory threshold for terrestrial soil organisms. Simulation of an annual application of two different pesticides for four years showed no recovery of the population until the end of the simulated period. In addition to the vertical soil consideration, the MIXCOP is also able to incorporate the temporal effect. This allows a kind of pesticide application history to be simulated for up to five years. The MITAS L model considers the horizontal distribution of pesticides in the landscape and their potential risk to soil organisms. Variable application amounts in cultivated areas are taken into account, as well as the exposure of field margins. In addition to a variable area-related risk, an average cumulative risk value can also be calculated for the entire simulation area. This allows calculation of a potential overall risk for new application methods, like in precision farming. Furthermore, this model is suitable as basis for a spatial risk assessment. This would enable calculation of a risk for various application scenarios for a landscape section consisting of arable land and field margins. This allows the ecotoxicological assessment of new application systems such as drones.Application examples are used to show that the model framework (MITAS+GUTS, MIXCOP and MITAS L) can be used for prospective and retrospective evaluation of pesticide effects in the landscape. Different spatial levels (vertical soil column & horizontal area), different organisational levels (individual organisms & population) as well as different impact calculations (risk indicator & effect) are considered within the framework. The application examples are used to identify the application limits, strength and weaknesses of the model framework. Potential for improvement and further development is identified as a result. The model framework based on MITAS+GUTS, MIXCOP and MITAS L is shown to be suitable for evaluating different pesticide application strategies. This could help to reduce chemical pollution in the agricultural landscape and its effects on soil organisms in the future.
2021
Knillmann S; Liess M; Scholz-Starke B; Daniels B; Ottermanns R; Schäffer A; Sybertz A; Roß-Nickoll M
Umweltbundesamt, Nr. 82/2021, 2021.
@techreport{Knillmann2021,
title = {Environmental risks of pesticides between forecast and reality: How reliable are results of the environmental risk assessment for individual products in the light of agricultural practice (tank mixtures, spray series)?},
author = {Saskia Knillmann and Matthias Liess and Björn Scholz-Starke and Benjamin Daniels and Richard Ottermanns and Andreas Schäffer and Alexandra Sybertz and Martina Roß-Nickoll},
doi = {https://doi.org/10.60810/openumwelt-7157 },
year = {2021},
date = {2021-05-31},
number = {82/2021},
institution = {Umweltbundesamt,},
abstract = {In our fields, several plant protection products (PPPs) are often applied at the same time and/or in sequence. In the current authorisation, however, PPPs are only evaluated individually. As a result, effects from typical PPP applications often remain undetected and represent a problematic and alarming gap in the authorisation of PPPs.
The authors of the present study evaluated almost 900 PPP spray series applied in 12 different main crops. The result: The overall risk of PPP applications is underestimated.
},
keywords = {},
pubstate = {published},
tppubtype = {techreport}
}
In our fields, several plant protection products (PPPs) are often applied at the same time and/or in sequence. In the current authorisation, however, PPPs are only evaluated individually. As a result, effects from typical PPP applications often remain undetected and represent a problematic and alarming gap in the authorisation of PPPs.
The authors of the present study evaluated almost 900 PPP spray series applied in 12 different main crops. The result: The overall risk of PPP applications is underestimated.
The authors of the present study evaluated almost 900 PPP spray series applied in 12 different main crops. The result: The overall risk of PPP applications is underestimated.
Toschki A; Oellers J; Rumohr Q; Roß-Nickoll M; Daniels B; Schäffer A; Sybertz A
Integriertes Monitoring in der Agrarlandschaft - Erfassung der ökologischen Auswirkungen des chemischen Pflanzenschutzes Forschungsbericht
Umweltbundesamt, Nr. 136/2021, 2021.
@techreport{nokey,
title = {Integriertes Monitoring in der Agrarlandschaft - Erfassung der ökologischen Auswirkungen des chemischen Pflanzenschutzes},
author = {Andreas Toschki and Johanna Oellers and Quintana Rumohr and Martina Roß-Nickoll and Benjamin Daniels and Andreas Schäffer and Alexandra Sybertz
},
doi = {10.4126/FRL01-006430025},
year = {2021},
date = {2021-03-31},
urldate = {2021-03-31},
number = {136/2021},
pages = {114 S.},
institution = {Umweltbundesamt,},
abstract = {Der alarmierende Rückgang der Biodiversität, insbesondere in der Agrarlandschaft, lässt Zweifel aufkommen, ob die derzeitige prospektive Risikoabschätzungs- und
Registrierungspraxis von Pflanzenschutzmitteln (PSM), die zu Pflanzenschutzzwecken eingesetzt werden, den gesetzlich vorgesehenen Schutz der Biodiversität gewährleistet. Als Hauptgrund dafür wird die allgemeine Intensivierung der Landwirtschaft genannt, die aus einem Komplex verschiedener Einflussfaktoren (z. B. Düngemitteleinsatz, Monokulturen) besteht. Ein wichtiger Faktor ist dabei der derzeitige Einsatz von PSM, die nachweislich negative Auswirkungen auf die Lebensgemeinschaften in landwirtschaftlichen Regionen haben. Die Auswirkungen der PSM auf die Biodiversität sind sowohl direkt als auch indirekt. Neben den direkten toxischen Wirkungen auf so genannte Nicht-Zielorganismen entstehen indirekte Effekte z. B. durch die Veränderung des durch Herbizide verursachten Konkurrenzverhältnisses zwischen Gräsern und Blütenpflanzen in der Vegetation. Folglich können die Wirkungen des chemischen Pflanzenschutzes in ihrer Gesamtheit nur durch retrospektive Ökosystembetrachtungen, d.h. durch Monitoringansätze, nachgewiesen werden. Da die Gemeinschaften im Freiland neben den bereits erwähnten PSM mit einem Komplex von verschiedenen Stressoren konfrontiert sind, müssen diese Stressoren in einem neuen retrospektiven Ansatz ebenfalls berücksichtigt werden. Wir stellen hier das Konzept eines neuen, integrierten Monitoringansatzes vor, auf dessen Grundlage die ökologischen Auswirkungen des PSM-Einsatzes in der Agrarlandschaft Deutschlands untersucht und bewertet werden sollen. Dabei sollen Synergien genutzt werden, indem das Monitoring in einem etablierten, bundesweiten ökologischen Flächenstichprobennetz durchgeführt und in die bestehenden Monitoringaktivitäten (z. B. Monitoring häufiger Brutvögel) integriert wird. Der geplante modulare Aufbau, d. h. die schrittweise Umsetzung einzelner Monitoring-Einheiten (analytische Endpunkte sowie Biodiversität bzw. die Untersuchung verschiedener taxonomischer Gruppen) werden aufgezeigt.},
keywords = {},
pubstate = {published},
tppubtype = {techreport}
}
Der alarmierende Rückgang der Biodiversität, insbesondere in der Agrarlandschaft, lässt Zweifel aufkommen, ob die derzeitige prospektive Risikoabschätzungs- und
Registrierungspraxis von Pflanzenschutzmitteln (PSM), die zu Pflanzenschutzzwecken eingesetzt werden, den gesetzlich vorgesehenen Schutz der Biodiversität gewährleistet. Als Hauptgrund dafür wird die allgemeine Intensivierung der Landwirtschaft genannt, die aus einem Komplex verschiedener Einflussfaktoren (z. B. Düngemitteleinsatz, Monokulturen) besteht. Ein wichtiger Faktor ist dabei der derzeitige Einsatz von PSM, die nachweislich negative Auswirkungen auf die Lebensgemeinschaften in landwirtschaftlichen Regionen haben. Die Auswirkungen der PSM auf die Biodiversität sind sowohl direkt als auch indirekt. Neben den direkten toxischen Wirkungen auf so genannte Nicht-Zielorganismen entstehen indirekte Effekte z. B. durch die Veränderung des durch Herbizide verursachten Konkurrenzverhältnisses zwischen Gräsern und Blütenpflanzen in der Vegetation. Folglich können die Wirkungen des chemischen Pflanzenschutzes in ihrer Gesamtheit nur durch retrospektive Ökosystembetrachtungen, d.h. durch Monitoringansätze, nachgewiesen werden. Da die Gemeinschaften im Freiland neben den bereits erwähnten PSM mit einem Komplex von verschiedenen Stressoren konfrontiert sind, müssen diese Stressoren in einem neuen retrospektiven Ansatz ebenfalls berücksichtigt werden. Wir stellen hier das Konzept eines neuen, integrierten Monitoringansatzes vor, auf dessen Grundlage die ökologischen Auswirkungen des PSM-Einsatzes in der Agrarlandschaft Deutschlands untersucht und bewertet werden sollen. Dabei sollen Synergien genutzt werden, indem das Monitoring in einem etablierten, bundesweiten ökologischen Flächenstichprobennetz durchgeführt und in die bestehenden Monitoringaktivitäten (z. B. Monitoring häufiger Brutvögel) integriert wird. Der geplante modulare Aufbau, d. h. die schrittweise Umsetzung einzelner Monitoring-Einheiten (analytische Endpunkte sowie Biodiversität bzw. die Untersuchung verschiedener taxonomischer Gruppen) werden aufgezeigt.
Registrierungspraxis von Pflanzenschutzmitteln (PSM), die zu Pflanzenschutzzwecken eingesetzt werden, den gesetzlich vorgesehenen Schutz der Biodiversität gewährleistet. Als Hauptgrund dafür wird die allgemeine Intensivierung der Landwirtschaft genannt, die aus einem Komplex verschiedener Einflussfaktoren (z. B. Düngemitteleinsatz, Monokulturen) besteht. Ein wichtiger Faktor ist dabei der derzeitige Einsatz von PSM, die nachweislich negative Auswirkungen auf die Lebensgemeinschaften in landwirtschaftlichen Regionen haben. Die Auswirkungen der PSM auf die Biodiversität sind sowohl direkt als auch indirekt. Neben den direkten toxischen Wirkungen auf so genannte Nicht-Zielorganismen entstehen indirekte Effekte z. B. durch die Veränderung des durch Herbizide verursachten Konkurrenzverhältnisses zwischen Gräsern und Blütenpflanzen in der Vegetation. Folglich können die Wirkungen des chemischen Pflanzenschutzes in ihrer Gesamtheit nur durch retrospektive Ökosystembetrachtungen, d.h. durch Monitoringansätze, nachgewiesen werden. Da die Gemeinschaften im Freiland neben den bereits erwähnten PSM mit einem Komplex von verschiedenen Stressoren konfrontiert sind, müssen diese Stressoren in einem neuen retrospektiven Ansatz ebenfalls berücksichtigt werden. Wir stellen hier das Konzept eines neuen, integrierten Monitoringansatzes vor, auf dessen Grundlage die ökologischen Auswirkungen des PSM-Einsatzes in der Agrarlandschaft Deutschlands untersucht und bewertet werden sollen. Dabei sollen Synergien genutzt werden, indem das Monitoring in einem etablierten, bundesweiten ökologischen Flächenstichprobennetz durchgeführt und in die bestehenden Monitoringaktivitäten (z. B. Monitoring häufiger Brutvögel) integriert wird. Der geplante modulare Aufbau, d. h. die schrittweise Umsetzung einzelner Monitoring-Einheiten (analytische Endpunkte sowie Biodiversität bzw. die Untersuchung verschiedener taxonomischer Gruppen) werden aufgezeigt.
2020
Sybertz A; Ottermanns R; Schäffer A; Scholz-Starke B; Daniels B; Frische T; Bär S; Ullrich C; Roß-Nickoll M
In: Science of The Total Environment, Bd. 710, 2020, ISSN: 0048-9697.
@article{Sybertz2020b,
title = {Simulating spray series of pesticides in agricultural practice reveals evidence for accumulation of environmental risk in soil},
author = {Alexandra Sybertz and Richard Ottermanns and Andreas Schäffer and Björn Scholz-Starke and Benjamin Daniels and Tobias Frische and Susanne Bär and Christian Ullrich and Martina Roß-Nickoll},
doi = {10.1016/j.scitotenv.2019.135004},
issn = {0048-9697},
year = {2020},
date = {2020-03-00},
urldate = {2020-03-00},
journal = {Science of The Total Environment},
volume = {710},
publisher = {Elsevier BV},
abstract = {Multiple pesticide residues in the environment originate from combination products with two or more active substances, from tank mixtures prepared by the farmers and from subsequent applications of pesticides in spray series. Consequently, mixtures of pesticide residues in agricultural soils are often detected long after application. To simulate the “accumulated mixture risk” towards earthworms resulting from a pesticide spray series for apple orchards, a model was applied considering both the dissipation of the applied pesticides over time and their individual toxicities. The model simulation for assessing the time-dependent mixture risk is applicable for several years and revealed that the “accumulated mixture risk” for earthworms clearly did not meet the threshold values for an acceptable risk according to the legal requirements in the EU approval procedure. Multiple pesticide residues from spray series are not yet considered in the environmental risk assessment (ERA) which is based on the application of single pesticide substances and products. We propose that the accumulation of residues during typical agricultural spray series should be included when assessing the risk of pesticides.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Multiple pesticide residues in the environment originate from combination products with two or more active substances, from tank mixtures prepared by the farmers and from subsequent applications of pesticides in spray series. Consequently, mixtures of pesticide residues in agricultural soils are often detected long after application. To simulate the “accumulated mixture risk” towards earthworms resulting from a pesticide spray series for apple orchards, a model was applied considering both the dissipation of the applied pesticides over time and their individual toxicities. The model simulation for assessing the time-dependent mixture risk is applicable for several years and revealed that the “accumulated mixture risk” for earthworms clearly did not meet the threshold values for an acceptable risk according to the legal requirements in the EU approval procedure. Multiple pesticide residues from spray series are not yet considered in the environmental risk assessment (ERA) which is based on the application of single pesticide substances and products. We propose that the accumulation of residues during typical agricultural spray series should be included when assessing the risk of pesticides.
Sybertz A; Roß-Nickoll M; Schäffer A; Scholz-Starke B; Daniels B; Ottermanns R
In: MethodsX, Bd. 7, 2020, ISSN: 2215-0161.
@article{Sybertz2020,
title = {MITAS: A model for assessing the time-dependent risk of sequential applications of pesticides for soil organisms by consideration of exposure, degradation and mixture toxicity},
author = {Alexandra Sybertz and Martina Roß-Nickoll and Andreas Schäffer and Björn Scholz-Starke and Benjamin Daniels and Richard Ottermanns},
doi = {10.1016/j.mex.2019.12.004},
issn = {2215-0161},
year = {2020},
date = {2020-00-00},
urldate = {2020-00-00},
journal = {MethodsX},
volume = {7},
publisher = {Elsevier BV},
abstract = {In agricultural landscapes it is common practice to apply pesticides as a spray series. Within a vegetation period multiple applications result in a mixture of different pesticides in the soil and other environmental compartments.
• A model named MITAS (MIxture Toxicity of Application Spray series) has been developed to calculate the soil concentration of pesticides and the resulting time-dependent mixture risk for earthworms. MITAS creates tables and graphs representing the mixture risk for an applied spray series time-dependently.
• A simulation of the impact of application series for a period of up to three years is possible with MITAS. Calculation of the soil concentration is based on the assumptions of the German pesticide registration. Mixture risk for each day within the entire modelling period is calculated.
• Mixtures of pesticides from former and multiple applications are the rule in agricultural soils as various studies have shown. Thus, considering the impact of pesticide mixtures is necessary to protect soil organisms. MITAS can assess not only the maximum mixture risk for soil organisms, but also how long a certain risk threshold may be exceeded, above which unacceptable effects on exposed organisms may occur.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In agricultural landscapes it is common practice to apply pesticides as a spray series. Within a vegetation period multiple applications result in a mixture of different pesticides in the soil and other environmental compartments.
• A model named MITAS (MIxture Toxicity of Application Spray series) has been developed to calculate the soil concentration of pesticides and the resulting time-dependent mixture risk for earthworms. MITAS creates tables and graphs representing the mixture risk for an applied spray series time-dependently.
• A simulation of the impact of application series for a period of up to three years is possible with MITAS. Calculation of the soil concentration is based on the assumptions of the German pesticide registration. Mixture risk for each day within the entire modelling period is calculated.
• Mixtures of pesticides from former and multiple applications are the rule in agricultural soils as various studies have shown. Thus, considering the impact of pesticide mixtures is necessary to protect soil organisms. MITAS can assess not only the maximum mixture risk for soil organisms, but also how long a certain risk threshold may be exceeded, above which unacceptable effects on exposed organisms may occur.