THE AMPHIBIAN SHORT TERM ASSAY (ASTA): DEVELOPMENT & EVALUATION OF AN INNOVATIVE & COST-EFFECTIVE SOLUTION FOR TESTING IMPACT OF ORGANOPHOSPHATE PESTICIDES ON AMPHIBIANS BEHAVIORAL TRAITS.
Neurotoxic pesticides are used worldwide to protect crops from insects. Developed at the beginning of the 20th century, they now represent a threat to non-target organisms that live in areas surrounded by treated crops. Many biochemical and cell-based solutions have been developed for testing insecticide neurotoxicity. Nevertheless, such solutions provide a partial assessment of the impact of neurotoxicity and there is a call for the development of solution including behavioral endpoints.
During my PhD, I enjoyed developping a 8-day method for assessing the impacts of organophosphate insecticides (OPI) on early stage of X. laevis, a model species for amphibians. This promising method implies the measurement of biochemical (AChE activity), morphometrical (lengths and shape) and locomotor traits[publication coming very soon]. For measuring the latter, I conceived a home-made device for recording larvae swimming behavior. I also developed a Python application for tracking larvae trajectories and computing different locomotor speed- and direction-related components.
For evaluating the efficiency of the method, I used two OPIs, the diazinon and the chlorpyrifos insecticide.
The results of this work are numerous:
- I was able to prove the efficiency of the method for highlighting the impact of these OPIs on AChE activity, body length and shape, growth rate and locomotor components,
- 6-day larvae were demonstrated to be the most relevant stage for testing OPIs,
- the impact of exposure on locomotor performance was time-dependent with day 6 as the most critical time.
I am confident that this method would be a good candidate for standardization after implementing improvement and leading few investigation about its repeatability and reproducibility. I am also confident that it would be tested with pharmaceuticals such as antidepressants.
Boualit, L., Cayuela, H., Ballu, A. , Cattin, L., Reis, C. & Chèvre, N. The Amphibian Short Term Assay (ASTA): Evaluation of a New Ecotoxicological Method for Amphibians Using Two Organophosphate Pesticides Commonly Found in Nature. Assessment of of behavioral traits. Environmental Toxicology and Chemistry (accepted)
Boualit, L., Cayuela, H., Cattin, L., & Chèvre, N. (2022). The Amphibian Short‐Term Assay: Evaluation of a New Ecotoxicological Method for Amphibians Using Two Organophosphate Pesticides Commonly Found in Nature—Assessment of Biochemical, Morphological, and Life‐History Traits. Environmental Toxicology and Chemistry, 41(11), 2688-2699.
Cayuela, H., Prunier, J. G., Laporte, M., Gippet, J. M., Boualit, L., Guérold, F., … & Jacob, G. (2021). Demography, genetics, and decline of a spatially structured population of lekking bird. Oecologia, 195(1), 117-129.
Cayuela, H., Boualit, L., Laporte, M., Prunier, J. G., Preiss, F., Laurent, A., ... & Jacob, G. (2019). Kin-dependent dispersal influences relatedness and genetic structuring in a lek system. Oecologia, 191(1), 97-112.
Boualit, L., Pichenot, J., Besnard, A., Helder, R., Joly, P., Cayuela, H., 2019. Environmentally mediated reproductive success predicts breeding dispersal decisions in an early successional amphibian. Animal Behaviour 149, 107–120. https://doi.org/10.1016/j.anbehav.2019.01.008
Cayuela, H., Boualit, L., Arsovski, D., Bonnaire, E., Pichenot, J., Bellec, A., … & Besnard, A. (2016). Does habitat unpredictability promote the evolution of a colonizer syndrome in amphibian metapopulations?. Ecology, 97(10), 2658-2670.