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 impact of agricultural intensification on farmland birds with an emphasis on pesticide exposure (new project) and the ecology of invasive species.
The effect of intensification on farmland birds with an emphasis on pesticide exposure
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 as the interface between the external compartment (i.e. the stressor) and the internal compartment (i.e. the physiology) of the individuals and how it drives populations dynamics. 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 agricultural practices and including pesticides. 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. Since 2017, experiments in controlled conditions on Grey partridges, Perdix perdix, have also been launched. The aim of these experiments is to understand the effects of pesticides on the physiology, the behaviour and the life history traits of the individuals in controlling the level of exposition in mimicry to the natural exposure. The first results are encouraging and suggest that realistic level of exposure to pesticides (even very low) impacts the physiology and the behaviour in cascading effects.
Jérôme Moreau (MCf) – UMR CNRS 6282 Biogéosciences, Dijon, France
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]).