Can parasites help “detoxify” their hosts ? Effects of element trace metals on feral pigeon parasites


These last decades, anthropic activities induced heavy chemical pollution. For example, we observe a pollution by element trace metals, which are naturally present in small amount in the environment, but whose concentration can be increased by some anthropic activities. Concentrations in element trace metals differ according to urbanization degree of the environment that we consider. In urban environment, we find those metals in high level concentrations, that negatively impact organisms living in those environments. Those negative effects on organisms have been studied a lot, but we don’t know much about the effect of those metals on ecological interactions, such as parasitism. Nevertheless, it has been shown that some parasites are able to accumulate pollutants in their own tissues, which allows to “detoxify” their hosts. So, those parasites would have a positive effect on their hosts in those polluted environments, by reducing trace metal rates in their hosts.

This project aims to understand if the presence of trace metals in the environment could impact a host-parasite interaction. We will test this hypothesis on feral pigeon (Columba livia), found a lot in urban areas and in which we observe a large diversity of parasites. The first axis will aim to determine if it could exist a benefit for the host fitness to be parasitized when he lives in polluted environment. The second axis will be to test if parasites accumulate pollutants in their tissues, which would allow a detoxification of their hosts. Finally, the third axis will be to verify if there exists a direct negative effect of pollutants on parasites, which would be less harmful for their hosts.