15 June 2022

Stéphane KRAUS – PhD defense

"Influence of social and environmental context on bumblebee nutrition"

PhD defense in french

Zoom link : https://us02web.zoom.us/j/83729748813?pwd=THpSOXp2RGZXdGJKalRkM2xSdDRYdz09

Supervisors : Jean-Marc Devaud et Mathieu Lihoreau

Comitee members :

  • Pr. Claire Detrain, Rapportrice, Université Libre de Bruxelles, Unité d’Écologie Sociale (USE), Bruxelles
  • Dr. Cédric Alaux, Rapporteur, INRAE PACA, UR 406 Abeilles et Environnement, Avignon
  • Dr. Jonathan Gerbore, Examinateur, Manager R&D, Koppert France, Cavaillon
  • Dr. Audrey Dussutour, Examinatrice, Université Paul Sabatier, CRCA-CBI, Equipe IVEP, Toulouse
  • Pr. Jean-Marc Devaud, Directeur, Université Paul Sabatier, CRCA-CBI, Equipe EXPLAIN, Toulouse
  • Dr. Mathieu Lihoreau, Directeur, Université Paul Sabatier, CRCA-CBI, Equipe EXPLAIN, Toulouse

Abstract :

For a few decades, the development of nutritional geometry has brought new insights into how individual animals eat and balance their acquisition of multiple nutrients simultaneously to maximize overall fitness. Yet, in social species, such as ants and bees, diet balancing is ensured by a minority of individuals that need to choose foods in order to meet their own needs as well as those of all other colony members whose needs may differ according to age, sex, caste, and the environmental conditions. In this thesis, I used nutritional ecology to study how bumblebees Bombus terrestris balance their nutrient collection across social and ecological contexts. To do so I designed cafeteria experiments in which individual bees or micro-colonies could balance their diet from artificial diets varying in their composition of carbohydrates, proteins and lipids. Bumblebees food collection tended to converge towards a well-defined nutritional target, irrespective of the age and body size of individuals. Yet, these nutritional decisions were influenced by extreme environmental conditions. Microcolonies deprived of brood did not regulate protein intake anymore and over-collected it. They adapted their diet to survive at sub-optimal temperatures, by focusing on specific macronutrients. At a lower temperature, bumblebees searched for the most sugar-rich diets available, while at a very high temperature they collected more water and/or lipids. Bumblebees as pollinators have a noteworthy economic value since their domestication, and with the current widespread declines of wild bees, manipulating the nutritional behaviour of domesticated species could selectively increase foraging activity and mitigate the ongoing pollination crisis.


15 June 2022, 14h0017h00
4R4-RDC | Salle Conférence