Adverse Outcome Pathways to assess effects of neonicotinoids on aquatic macroinvertebrates

Adverse Outcome Pathways to assess effects of neonicotinoids on aquatic macroinvertebrates

Marelize Labuschagne (PhD), Victor Wepener, Hannes Erasmus, Wynand Malherbe

Commenced 2022


The adverse outcomes pathway (AOP) is a conceptual framework that can be used to show the linkages between sub-cellular initiating events and adverse outcomes. The AOP framework therefore integrates ecotoxicological processes across all levels of biology. Adverse Outcome Pathways is a new tool that have been proposed to assess the risks associated with pesticide exposure and ecotoxicological research (OECD guideline 233). This method provides a hierarchical framework to link molecular initiating events with key events by measuring behavioural responses of organisms individually and trophic responses of communities to adverse outcomes based on an ecotoxicological response. Understanding ecotoxicology at the molecular level is crucial in interpreting the mechanisms that bring about alterations observed at organ or whole-organism level.

It is not clear how causal pathways at molecular level can predict adverse outcomes at higher levels of biological organisation due to the complex interactions. Mesocosms offer a more realistic alternative to field surveys, while allowing the isolation and examination of potential stressors in a controlled experimental environment without the influence of external factors. This method has proven to produce more ecological realism than laboratory bioassays alone and allow for the identification of potential interactions between aquatic communities and ecosystem function. This will provide in vitro and in vivo-level data for the hazard classification of a pyrethroid (deltematherin) and a neonicotinoid (imidacloprid) via their mode of toxic action and link these to higher level adverse outcomes such as changes in invertebrate populations or community structures. In the end these results will aid to better understand and manage the safety and risks of vector control.


Determine the sublethal effects of deltamethrin and imidacloprid on population and community structure. This will be done by determining the Adverse Outcomes through changes in aquatic macroinvertebrate communities in long-term observations by using a mesocosm approach

This includes studying the following: nutrients, pH, conductivity, total dissolved solids, dissolved oxygen, water, sediment, phytoplankton, periphyton, zooplankton, microbial communities, macrophyte coverage, sediment, diatoms and organic decomposition.

Expected outcomes

It is expected to see how the insecticides effects all communities and parameters within the mesocosms and then to see of these communities can recover after the application of the insecticides have been stopped.


Benefit to interdisciplinary objectives of the UESM

The methods that will be used were obtained during a research visit to the Netherlands, where they are the leading experts. During this study different disciplines will be included since this study will investigate different aspects within the mesocosms, this will include ecology, ecotoxicology, botany and microbiology.

Project status

In progress


No preliminary results available yet.


Last updated: 11 November 2022