FAUVERGUE , Xavier

Like other animals and plants, insects may find it difficult to survive and reproduce in small populations, to the extent that their long-term persistence may be jeopardized. The Allee effect is a theoretical framework that formalizes this decrease in survival or reproduction in small populations, and the resulting decrease in population growth...

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In insects, mating often occurs after natal dispersal, and hence relies on a coevolved combination of sexual communication and movement allowing mate encounter. Volatile sex pheromones are widespread, generally emitted by females and triggering in-flight orientation of conspecific males. In parasitoid wasps, unmated females can start laying...

International audience

To predict the effect of density on the dispersal of foraging parasitoids, we developed a spatiallyexplicit individual-based model in which parasitoids move among host patches at random but use an optimal decision-rule about when to leave these patches. We used a simple decision rulewhere an individual forager exploits a patch as long as the...

Chez une soixantaine d'espèces d'hyménoptères haplo-diploïdes, et parmi elles des espèces d'intérêt comme l'abeille ou encore les parasitoïdes utilisés en lutte biologique, le sexe est déterminé par un seul gène. Les mâles sont haploïdes hémizygotes tandis que les femelles sont diploïdes hétérozygotes. Cependant, les croisements entre individus...

To predict the effect of density on the dispersal of foraging parasitoids, we developed a spatiallyexplicit individual-based model in which parasitoids move among host patches at random but use an optimal decision-rule about when to leave these patches. We used a simple decision rulewhere an individual forager exploits a patch as long as the...

International audience

1. Optimal foraging models ultimately predict that female parasitoids should exploit rich host patches for longer than poorer ones. At the proximate level, mechanistic models and experimental studies show that parasitoids use both chemicals produced by their hosts and direct encounters with their hosts to estimate patch quality. Although it has...

International audience

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Animals foraging for patchily distributed resources may optimize their foraging decisions concerning the patches they encounter, provided that they base these decisions on reliable information about the profitability of the habitat as a whole. Females of the parasitoid Lysiphlebus testaceipes exploit aphid hosts, which typically aggregate in...

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In reaction to herbivore attack, plants attract herbivores' natural enemies by emitting a chemical signal. Based on a litterature review, we documented the response of parasitoids to these Herbivore Induced Plant Volatiles (HIPV): the behavior of 60 parasitoid species was characterized, and general patterns emerged between the way parasitoids...

Many parasitoid species use olfactory cues to locate their hosts. In tritrophic systems, parasitoids of herbivores can exploit the chemical blends emitted by plants in reaction to herbivore-induced damage, known as herbivore-induced plant volatiles (HIPVs). In this study, we explored the specificity and innateness of parasitoid responses to...

International audience

In sexual organisms, low population density can result in mating failures and subsequently yields a low population growth rate and high chance of extinction. For species that are in tight interaction, as in host-parasitoid systems, population dynamics are primarily constrained by demographic interdependences, so that mating failures may have...

National audience

National audience

Extinctions have no simple determinism, but rather result from complex interplays between environmental factors and demographic‐genetic feedback that occur at small population size. Inbreeding depression has been assumed to be a major trigger of extinction vortices, yet very few models have studied its consequences in dynamic populations with...

1. The management of insect pests has long been dominated by the use of chemical insecticides, with the aim of instantaneously killing enough individuals to limit their damage. To minimize unwanted consequences, environmentally friendly approaches have been proposed that utilize biological control and take advantage of intrinsic demographic...

Mating failures at low density – a common type of Allee effect – can reduce the per capita reproductive rate and, if severe enough, doom small populations to extinction. Parasitoids frequently undergo low densities triggered by their typically cyclic dynamic and/or the bottlenecks they experience when introduced for the biological control of...