The role of biotic interactions in a prey-predator system : the case of predation and regulation of weed seeds by carabids.

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…

Toward a better prediction of in-field weed regulation by carabid beetles in European arable landscapes

International audience; Arable agriculture is still highly reliant on herbicides to manage weeds. As part of the necessary shift towards a reduction in pesticide use, the regulatory effect of seed-eating carabid beetles on weeds has received increasing attention in agroecological research. While strong evidence points to carabids exerting a regulatory effect on certain weed species, it is difficult to predict whether a particular assemblage of carabid species will drive the function of weed seed predation in field conditions. There are also uncertainties about which key local and landscape-scale factors affect the function of weed seed predation. In this paper, we report on specific researc…

Key carabid species drive spring weed seed predation of Viola arvensis

Intraspecific interference does not reduce weed seed consumption in two carabid species

National audience

Participation à la fête de la nature et de la biodiversité au Jardin des Sciences du Parc de l’Arquebuse à Dijon le dimanche 21 mai 2017

Quantification of the contribution of weed seed predators to crop yield

30 book of abstracts; International audience

Vers une meilleure compréhension de la prédation des graines adventices par les carabes en grandes cultures

National audience

Seed availability, intraspecific interference and their interaction drive per capita weed seed consumption by carabid beetles

National audience

Effects of seed and carabid densities on the weed seed predation service

National audience; Farming relies heavily on pesticides in order to maintain/increase crop production, yet, awareness of the adverse effects of pesticides on the environment and on biodiversity has triggered the search for alternative, non-chemical, pest management strategies. In arable systems, weeds remain one of the most challenging management issue. Recent research suggest that the depletion of weed seeds by naturally occurring seed consumers could impact the dynamics of problematic weeds and in temperate systems, carabid beetles are the main invertebrate consumers of weed seeds. However, predicting weed seed depletion rates in field conditions remains difficult, as carabid trophic resp…

Diversity of foraging strategies and responses to predator interference in seed-eating carabid beetles

12 pages; International audience; The prediction of pest regulation by multi-predator communities often remains challenging because of variable and opposite effects of niche complementarity and predator interference. Carabid communities are regulating weeds in arable fields and include a mix of species ranging from granivores to predators that are obligate omnivores. It is not clear from field studies whether granivore and obligate omnivore species either contribute equally or are complementary in the process of weed suppression, and little is known about the impact of potential predator interference within carabid communities on weed suppression. We compared the weed seed foraging strategy…

Toward a better understanding of in-field weed regulation by carabid beetles, and their functional characteristics, in European arable landscapes

For future arable agriculture, there is a need for more sustainable methods to manage weeds that are less reliant on herbicides and maintain food production. Control of weeds by natural enemies is an agro-ecological alternative to reduce the use of herbicides. While strong evidence points to carabid beetles exerting a regulatory effect on certain weed species, it is difficult to predict whether a particular assemblage of carabid species or functional groups will drive the function of weed seed predation in field conditions. There are also uncertainties about which key local and landscape-scale factors affect the function of weed seed predation, and the functional characteristics of carabid …

Le paysage et les pratiques agricoles affectent les carabes régulateurs des adventices, e façon directe ou en modulant la disponibilit´e de leurs ressources trophiques : une analyse pan-européenne

National audience; Les carabes sont des agents de lutte biologique importants qui contribuent au service´ecosyst´emique de r´egulation du stock semencier des adventices gr^ace `a la pr´edation desgraines. Pour encourager l’adoption de ce service par les agriculteurs, il est crucial d’´evaluerla contribution des carabes `a cette r´egulation, et de mieux comprendre les d´eterminants deleur pr´esence dans les parcelles. La complexit´e du paysage et l’intensit´e de la gestion agricole peuvent directement affecter les carabes. Cet effet peut ´egalement ^etre indirect, via unemodulation des ressources trophiques disponibles pour les carabes, bien que peu d´ecrit dansla litt´erature.Nous avons ´ev…