Conférences plénières

Quatre conférencières et conférenciers ainsi que la lauréate du prix Jeune Chercheuse - Jeune Chercheur 2023 sont invité.e.s à présenter leur travaux

When successfully invading an area, the Argentine ant displaces almost all other ant species becoming the dominant ant species and at very high density; it also modifies communities of invertebrates. These impacts on invertebrates can have cascading effects in the ecosystems, causing indirect impacts on vertebrates; besides, the Argentine ant can also have direct impacts on vertebrates. In this talk I will describe some of these impacts. First, the varying impacts of the Argentine ant on its predators could be depending on their dietary specialization; for example, some myrmecophagous amphibian species could have their individual growth and survival compromised, the quality of the territory could be reduced, shifts in their territories could occur, or behavioral patterns could be altered. Second, indirect effects could consist in prey shifts, when their prey availability is reduced due to the invasion of Argentine ant. This can also cause territory shifts or reduction in reproduction or survival, for example in passerine birds nesting in invading areas. Third, direct effects can also consist on harassment or disturbance, because of their abundance in the successfully invaded area; this has been observed occasionally mainly in birds nesting in the soil, and more recently in birds nesting in trees that are colonized by the Argentine ant. Fourth, I will describe the discovery of the venom of the Argentine ant and the impacts in juvenile amphibian. I will finish this talk by describing some of the gaps in the knowledge of the impacts of the Argentine ant in vertebrates.

The fly -Drosophila melanogaster- is an outstanding species for investigating how genes influence behaviour. Available tools mean that a behaviour for which a causal gene is identified can be studied at the single neuron and circuit level. This has been used to elucidate the molecular and cellular basis of behaviours such as courtship and aggression. But can Drosophila be used to investigate more complex social behaviours?  In this lecture, I will introduce the social life of Drosophila: how flies form groups and how group membership affects their reproductive performance. By showing how these behaviours are being dissected at the mechanistic level, I hope to convince the audience that Drosophila can be a useful model to reveal mechanisms that mediate more complex forms of sociality. 

Sociality is considered as one of the major transitions in evolution, and the most advanced level of sociality is found in eusocial insect societies. The success of social insect colonies lies in the capacity of all members of the society to behave in a well-organized and context-dependent manner, thanks to elaborate communication among colony members. Honey bees, in particular, use a sophisticated chemical communication system based on the use of a high number of pheromones, most of which have already been identified. How does the social insect brain manage to encode such a plethora of highly‐meaningful and ecologically‐relevant signals? Does it encode social pheromones using dedicated pathways (labeled-line system), a relevant strategy when only a few pheromones are used by the animal (i.e. sexual pheromone), or does it use a combinatorial strategy, in the manner of general odorants? Did evolution maintain in the social brain the costly strategy involving as many labeled lines as social pheromones, or did it evolve a more cost-effective strategy? My research tries to answer these questions by using heterologous expression of honey bee olfactory receptors, electrophysiological recordings and in vivo optical imaging (using GCaMP-expressing bees) to study the peripheral and central circuits involved in pheromone processing in the honey bee brain. 

Cette conférence sera ouverte à tous les membres du Centre de Biologie Intégrative de Toulouse

Sous nos climats, les interactions plantes-fourmis passent presque toujours par un hémiptère (cochenille ou puceron). Sous les tropiques, de nombreuses fourmis sont arboricoles. Les espèces territoriales-dominantes ont des colonies de plusieurs centaines de milliers à plusieurs millions d’individus, occupant la cime de plusieurs arbres. Leurs nids sont généralement en carton, mais il y a aussi des fourmis charpentières et tisserandes. Du fait de la taille de ces colonies, elles seront considérées comme "herbivores" car elles tirent leur nourriture de leurs relations avec des hémiptères. Toutefois, elles sont presque toutes prédatrices, parfois même très spécialisées. Les fourmis associées à des myrmécophytes trouveront leur logement dans des structures creuses (base des feuilles, épines et tiges creuses) et leur nourriture sous forme de nectar extrafloral ou de corps nourriciers. On trouvera ici des espèces qui construisent des pièges à base de carton pour capturer leurs proies, ou d’autres qui utilisent l’effet Velcro^® avec une plus grande efficacité. Enfin, les jardins de fourmis sont des associations entre des espèces arboricoles et des épiphytes, les fourmis construisant un nid en carton riche en nutriments dans lequel elles vont semer des graines d’épiphytes qui se développeront, engainant le système. Ces espèces se nourrissent de nectar extrafloral, exploitent des hémiptères et sont, ici aussi, prédatrices. Ainsi quasi toutes ces espèces sont prédatrices dans un contexte en trois dimensions. Nous regarderons quelles sont leurs stratégies pour ne pas perdre leurs proies, en particulier l’efficacité de leur venin.

Group living is a ubiquitous phenomenon in animal kingdom but highly variable across species. It extends from aggregations of unrelated individuals to temporary family groups and further to complex and permanent societies with a division of labour. Yet, understanding why animals live in a group and how sociality in all its forms has evolved and maintained, still remains a central question in evolutionary biology. Currently, this question has been mainly studied in species with obligatory and permanent group life, but the cost:benefit ratio of cooperation and competition among individuals remains unclear in species with facultative and temporary social life. I will explore this question through the diversity of social interactions which impact the lives of individuals living in these groups. To do that I will go through the results of empirical work done with two insect species with different levels of sociality, the European earwig which has a facultative family life and the pine sawflies where individuals are social and cooperative only during the larval stage. These new and promising model systems offer a unique opportunity to test the importance of siblings ‘interactions in the early evolution of family life, to study how ecological and social factors select costly cooperative behaviour and what are the genetic and environmental sources for the variation in cooperative traits. Overall, my findings emphasize the need to study the evolutionary and ecological drivers of social interactions in species with different levels of sociality and more particularly in species where all members can switch from group (e.g family) to solitary life - a scenario that probably prevailed in the early evolution of sociality.