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Thesis started november 3^rd, 2014 - Defended in december 19^th
Fund: ANSES/Region Bretagne
Direction: Eric GRENIER (INRA) et Laurent FOLCHER (ANSES)

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Abstract :

Plant-parasitic nematodes (PPN) are microscopic worms that occur in communities in almost every agricultural soils. Commonly found PPN are usually harmless for the plants. However, M. chitwoodi, a PPN highly regulated in EU can induce important yield losses. In order to improve risk assessment of M. chitwoodi implantation, we studied French native PPN communities to identify those that can limit its development shortly after an introduction. We firstly described PPN communities in various agrosystems, at a landscape scale and then in nine French regions. Despite the quite homogeneous species richness observed across the fields sampled, we highlighted strong PPN taxa abundance variations. Environmental variables seemed to mainly drive the PPN communities structure at a large geographic scale but cultural practices (tillage and pesticides uses) seemed to explain the communities variation at the local scale. Secondly, we studied the capacity of different PPN communities to limit M. chitwoodi development through competition. It appeared that PPN communities with high global abundance, regardless of the taxa present, are able to decrease M. chitwoodi multiplication. The results of this PhD thesis bring some elements about the structure and functioning of PPN communities in French fields and their ability to reduce the M. chitwoodi development in order to predict its implantation risk.​

Poster pdf