Impact of Starvation on Lasius niger' Exploration

Exploration allows animals to discover food resources, detect competitors and update their general knowledge of the habitat surroundings. Although the vital importance of exploration, its functional and proximal complexity is often underestimated. In this article, we study the exploring activities of Lasius niger, an aphid-tending ant species that has frequently to face fluctuations in honeydew availability. We study how foragers adjust collectively their exploration strategy to starvation to evidence the mechanisms involved in the adjustment of exploration to the food needs. We also study the social interactions between explorers and nestmates in order to enlighten the individual mechanisms regulating the exploring strategies according to starvation. Our experiments showed that the proportion of nestmates leaving the nest increases twofold after a prolonged starvation of 8 d. Highly starved scouts do not trigger the departure of nestmates by a direct physical contact (antennation) and do not trigger the departure by laying a trail pheromone as they do to recruit nestmates to a food resource. After long starvation periods, higher nestmates mobilisation seems to be based on their increased motivation to leave the nest and explore a new area. This study of social interactions has deciphered the importance of the role allocated to each behavioural group during boosted exploration.