The increase of human activities worldwide has largely contributed to large scale cascading effects on the ecosystems. In this context, I am mainly interested in two main topics: the ecology of invasive species and the impact of agricultural intensification on farmland birds (new project).
Ecology of invasive species
In the last decades, biological invasions have increased worldwide and alien species are often considered one of the major threat to biodiversity. Social hymenopterans are prone to be successful at colonisation because sociality promotes flexibility. Several Vespidae are invasive throughout the world and impact local ecology, economic and human health. The Yellow-legged hornet (Vespa velutina) was introduced into southwestern France before 2004. Since its accidental introduction, its population has expanded through the French territory but also to Spain, Portugal, Italy, Germany and more recently UK. This social hymenoptera is a predator of honeybees. However, contrarily to their Asian counterpart (Apis cerana), European honeybee (A. mellifera) does not display efficient anti-predator behaviour. Hornet workers prey intensively on honeybees to feed their larvae. Since several years, beekeepers face heavily losses in their livestock due to different factors (pesticides, Varroa, habitat fragmentation and losses…) and V. velutina is thus an additional source of stress for honeybees, potentially contributing to their decline in Europe. Little is known about V. velutina (except its hunting activity on honeybees). The knowledge of the ecology and behaviour of this invasive pest is thus of major interest to provide efficient management program (see our recent review [PDF]).
Denis Thiéry (DR), Olivier Bonnard (TR) & Juliette Poidatz (PhD student) – INRA 1065 SAVE, Villenave d’Ornon, France
The effect of intensification on farmland birds
In the last century, the farmland landscape has been largely reduced to the benefit of urban areas and modified due to intensification. Contrary to the effect of urbanization on the behaviour of the bird species, the effects of the intensification on farmland birds has been neglected while it is considered a major factor in their decline. Several factors are potentially responsible of such decline among which the loss of resources, the fragmentation/destruction of habitats or the mechanization of practices. The intensification of the agricultural is also intimately linked to the use of pesticides that impact the whole ecosystems. However, to date, their impact on the decline of avian species has been poorly studied and is still controversial. Most studies were indeed carried out on captive animals, which do not, actually, reflect the true exposition to pesticides in wild conditions. My main interest is to understand the role of behaviour (namely personality) as the interface between the external compartment (i.e. the human perturbations) and the internal compartment (i.e. the physiology) of the individuals and its implication in for evolutionary processes. This work is realized on the Montagu’s harrier, Circus pygargus. Adults breed in France in cereal crops, on the ground making the chicks directly exposed to pesticides and to mechanization. As a migratory species, behaviour and physiological state may also influence the outcomes of the migration. Harriers exhibit typical carotenoid-based coloration involved in a trade-off between the immune system and reproduction that can be altered due to the stress and/or pesticide exposition. This project benefits from the long-term monitoring of the Montagu’s harrier within the Long-Term Ecosystem Research Zone Atelier Plaine & Val de Sèvre (ZA_PVS). In this area, Montagu’s harrier nests are located every year since 1994, monitored and protected.
Vincent Bretagnolle (DR) & Juliette Rabdeau (PhD student) – UMR 7372 CNRS-Université de La Rochelle CEBC
Jérôme Moreau (MCf) – UMR CNRS 6282 Biogéosciences, Dijon, France