Optical bioassay for measuring sublethal toxicity of insecticides in Daphnia pulex

Abstract

Many emerging contaminants tend to be biologically active at very low concentrations, occur in water as part of complex mixtures, and impact biota in ways that are not detected using traditional toxicity tests (e.g., median lethal concentration). To evaluate emerging contaminants, the authors developed a method for detecting sublethal behavioral effects by quantifying the swimming behavior of Daphnia pulex, a model organism for studying aquatic toxicity. This optical tracking technique is capable of measuring many swimming parameters, 2 of which-cumulative distance and angular change-are presented. To validate this technique, 2 prototypical compounds that exhibit different modes of action as well as corresponding insecticides that are commonly found in surface waters were investigated. The acetylcholinesterase (AChE) inhibitor physostigmine was used as the prototypical compound for the large number of AChE inhibitor insecticides (e.g., chlorpyrifos). Nicotine was used as the prototypical compound for neonicotinoid insecticides (e.g., imidacloprid). Results demonstrate that this assay is capable of detecting sublethal behavioral effects that are concentration-dependent and that insecticides with the same mode of action yield similar results. The method can easily be scaled up to serve as a high-throughput screening tool to detect sublethal toxic effects of a variety of chemicals. This method is likely to aid in enhancing the current understanding of emerging contaminants and to serve as a novel water-quality screening tool.

Exposure to D2-like dopamine receptor agonists inhibits swimming in Daphnia magna

“…However, at the present time there is not a low-cost, widely adopted, standardized method of assaying the acute behavioral response of Daphnia to drugs or changes in environmental conditions. Rather, there are a variety of such methods (Wiklund et al, 2011) that have been used and report a variety of parameters that describe Daphnia movement (Artells et al, 2013;Dodson and Ramacharan, 1991;Dodson et al, 1997;Ekvall et al, 2013;Lovern et al, 2007;Zein et al, 2014). Here we report on the development of a new, inexpensive, and accessible assay and an efficient pipeline for data collection to facilitate behavioral neuropharmacology studies of D. magna.…”

“…Two recent papers report new two-dimensional imaging and analysis tools to study Daphnia that allows for quantification of distance moved and angular velocity (Artells et al, 2013;Zein et al, 2014).…”

Exploration of Daphnia behavioral effect profiles induced by a broad range of toxicants with different modes of action

“…For instance, the DaphTox ® (Bbe ® Moldaenke, Kiel, Germany) system was successfully used as a BEWS for detecting chemical pollution in surface water or intakes for drinking water production in northern Europe [17] Acc e p ted P r e p r i nt chemicals according to their mode of action may potentially facilitate the extrapolation of observed behavioral effect profiles and the time of effect onset to compounds with a similar mode of action. Theoretically, compounds sharing a mode of action should behave in a similar manner and should show similar toxic effects and thus behavioral effects [11].…”

The Novel Concept of “Behavioural Instability” and Its Potential Applications

“…The concept of behavioural instability could have several possible applications as a biomonitoring tool if we expect that changes in environmental conditions can produce changes in the behavioural traits. For example, behavioural traits have been used in toxicological studies as a sensitive indicator of stress using traits such as swimming activity, locomotor activity or flight [30][31][32][33]. Behavioural instability provides another way of analysing data compared to traditional measures such as total distance traveled, activity per hour or swimming distance.…”