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The risk of contracting tick-borne diseases depends on the interactions between vertebrate hosts, ticks and pathogens in their ecosystem. Indeed, the abundance of each and their relationships depend on the configuration of the landscape.
Within the framework of the ANR OSCAR project, the UMR BIOEPAR has studied the relationships between the characteristics of a bocage landscape, micro-mammals and the tick Ixodes ricinus, as a vector of zoonoses. In particular, the UMR BIOEPAR characterized micro-mammals as hosts for tick larvae. Two species of rodents were abundant on the edge of meadows, the woodland mouse and the bank vole.

The study showed that the structure of the landscape (wooded area, length of hedges) influenced rodent populations. Thus, certain landscape elements, such as the density of the hedge and copse network, are favourable for woodland field mice, while bank voles are more abundant in isolated habitats. The field mouse appeared to be a better host for tick larvae, with a positive influence on the number of ticks in the environment, while the contribution of bank voles as hosts for larvae varied seasonally. One explanation would be that rusty voles acquire immune resistance to ticks as adults and that only young fall voles are good hosts for larvae. Despite this, tick numbers were only weakly related to rodent numbers, probably due to the influence of other factors (weather, vegetation). This work is in line with current questions about the role of biodiversity on the circulation of infectious diseases transmissible to humans and domestic animals.

This study shows that the landscape can influence the number of ticks by playing on the number of micro-mammal hosts of each species. As these species are more or less efficient reservoirs of pathogens, their circulation could also be modified by the landscape. Investigations on these pathogens are ongoing.

Partners: Grégoire Perez was co-supervised by Alain Butet, research fellow in the UMR Université-CNRS Ecobio (Rennes) and by Suzanne Bastian, Associate Professor in the UMR Inra-Oniris BIOEPAR (Nantes). It was funded by a doctoral grant from the Brittany region.

Associated publication: Perez, G., Bastian, S., Agoulon, A., Bouju, A., Durand, A., Faille, F., Lebert, I., Rantier, Y., Plantard, O., & Butet, A. (2016). Effect of landscape features on the relationship between Ixodes ricinus ticks and their small mammal hosts. Parasites & Vectors, 9.  http://dx.doi.org/10.1186/s13071-016-1296-9

Contacts

Scientific contacts :

•  Olivier Plantard UMR BIOEPAR
•  Suzanne Bastian UMR BIOEPAR

Associated Department : Santé animale
Associated Centre: Angers-Nantes Pays de la Loire

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ANR OSCAR Program

Study of the acarological risk according to the landscape in bocage agro-ecosystems.

This programme is coordinated by UMR BIOEPAR and involves 5 laboratories working on the ecology of hosts, vectors and pathogens.

https://www6.inra.fr/oscar

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