Search results for "Biotic interactions"
showing 5 items of 15 documents
The role of biotic interactions in a prey-predator system : the case of predation and regulation of weed seeds by carabids.
2020
For the transition towards agricultural production systems that are less dependent on herbicides, the use of weed regulation by seed-eating carabids is of great interest. Weed seed predation by carabids is variable and occurs within a complex context of many biotic interactions. This complexity partly explains our current inability to predict levels of in-field weed regulation. In this thesis, I analysed variations in the levels of predation and biological regulation of weeds and determined how they respond to two classes of biotic interactions: 1) the availability of alternative prey; and, 2) intra- and inter-specific interactions between the carabids themselves. Field measurements carried…
Stability of consumption pattern in two seed eating carabid species
2017
SPEGESTADDOCT INRA; Carabids can eat a substantial amount of seeds of weeds per day and are considered as credible biocontrol agents for the regulation of weeds in arable fields. Carabids species belong to either granivore, omnivore or carnivore trophic guilds and we expected each of these to have specific patterns of weed seed consumption and specific responses to biotic interactions. These differences will impact the total predation rate of a carabid community and may also explain why it is difficult to predict the efficiency of carabid biocontrol service. To test this expectation, we looked at the consumption pattern of two species of carabids species common in arable fields, one known a…
Biocontrol of the parasitic plant species Phelipanche ramosa, using rapeseed rhizosphere fungi or phytotoxic metabolites they produce.
2019
Phelipanche ramosa (L.) Pomel, branched broomrape, is a major root-holoparasitic damaging weed with a large host range besides a strong adaptation to rapeseed. Broomrape seed germination is necessarily triggered by host root exudates. This ensures that they germinate close to a host root where they attach and establish a vascular connection to take up water and nutrients. No efficient broomrape management technique has been validated yet. Biocontrol could be an alternative but there is currently no biological control agent on the market. Indeed tripartite interactions between the host plant, the parasitic plant and a pathogenic agent of the latter are complex and poorly understood. The obje…
Biocontrol of Phelipanche ramosa, a parasitic weed of rapeseed in France, using soil-borne fungi
2021
National audience; Phelipanche ramosa is a major holoparasitic weed, which became a major agronomic problemfor rapeseed crops in France. Weed control in rapeseed does not have a direct impact on thisparasitic weed whose half of the reproductive cycle occurs on the root system of its host. Since1990, broomrape expanded its distribution area starting from the Poitou-Charentes region.Necrosis symptoms on broomrapes from this region should be indicators of potentialpathogenic fungi. Furthermore, these pathogenic fungi should be able to infest differentbroomrape stages. The aim of my thesis is to contribute to the evaluation of an integrated controlsolution for this parasitic weed and focus on t…
Unraveling biotic interactions determining soil microbial community assembly and functioning
2019
National audience; Microbial communities are at the heart of all ecosystems and yet, a sound understanding of the ecological processes governing the assembly of these communities in the environment is missing. To address the role of biotic interactions in assembly and functioning of the soil microbiota, we used a top down manipulation approach based on the removal of various populations in a natural microbial community. Suspensions of the soil microbiota were subjected to various biocidal and filtration treatments before being inoculated into the same sterilized soil. We hypothesized that if biotic interactions are an important shaping force of the microbiota assembly, removal of microbial …