Biology subjects

Doussot, C.

Publications and source records attributed to Doussot, C..

5 recordsLinked to original sources

bioRxiv2025

Social attraction mediates collective foraging decisions in invasive hornets

Group-living animals commonly use social information to better locate and exploit resources. In many insects, birds, fish and mammals, this can lead to collective foraging decisions by which animals share a single food source among alternatives of equal qualities. Here, we report collective foraging decisions in a social wasp, the yellow-legged hornet Vespa velutina nigrithorax, a major predator of bees and other terrestrial invertebrates invasive across Asia, Europe and North America. When given a choice between two identical liquid food sources (feeders or traps containing sugar solutions), wild hornets distributed asymmetrically on the two options, and this phenomenon was more frequent as group size increased. Priming one of the food sources with dead hornets predictably biased the collective choices towards this particular option, irrespective of whether the dead insects were conspecifics or hornets from a closely related species. Inter-attraction in yellow-legged hornets is thus a passive and non-specific mechanism, possibly mediated by visual or chemical cues displayed by dead hornets. This collective behaviour may provide important foraging advantages to hornets invading new territories and bring new perspectives for population control.

animal behavior and cognition↗

bioRxiv2025

Human performance in the Traveling Salesman Problem is influenced by spatial scale

Like many other animals, we humans frequently face complex route optimization problems when planning journeys between multiple locations. Several strategies can be employed to approach such Traveling Salesman Problems. However, these may be strongly constrained by spatial scales, for instance if the goal is to navigate in a supermarket, in a city, or across a continent. Here, we monitored the route optimization performances of human subjects collecting objects in a video game simulating 3D environments at various spatial scales. Unexpectedly, route optimization performances peaked at intermediate spatial scales, where participants could use global optimization strategies. At very large and very small spatial scales, however, participants predominantly employed less efficient local optimization strategies. At the very large scale, the considerable distances between objects prevented them from being seen all at once, making global planning difficult. At the very small scale, participants reported having chosen the shortest path, although they did not. This mismatch between perceived and actual performances suggests suboptimal alternatives were sufficiently short to be considered equivalent to the optimal route. Spatial scale thus strongly influences route planning in human navigators and may determine the spatial behaviors of a wide range of animals facing similar routing problems in their everyday lives.

animal behavior and cognition↗

bioRxiv2025

Male bumblebees adapt foraging to environmental conditions to sustain mate-seeking efforts

Male bees navigate complex trade-offs between energy acquisition and reproductive signalling, yet their movement strategies remain understudied. Unlike workers that optimise foraging to support the colony, males forage independently to collect nectar and deposit sex pheromones on selected plants. Using high-resolution 3D tracking in an indoor flight cage, we investigated how the spatial arrangement of nectar and scent-marking sites, along with nectar availability, influence male movement patterns. We manipulated the distribution of feeders (artificial flowers) and scent-marking locations (branches), and varied nectar delivery rates, to assess effects on foraging, scent-marking, and patrolling. Males responded strongly to spatial structure: in clumped arrays with evenly spaced resources, movements between consecutive visits were shorter and more localised, while in dispersed arrays with irregular spacing, transitions were longer and more variable. The combination of dispersed spacing and low nectar availability imposed the highest foraging demands, resulting in fewer feeding events and reduced total feeding time. Despite these increased costs, males maintained consistent investment in reproductive behaviours, suggesting a prioritisation of mate-seeking over energy gain. Rather than reducing signalling, males adjusted their foraging strategy--favouring fewer but prolonged feeding bouts when nectar availability allowed. These findings reveal a unidirectional behavioural adjustment, in which foraging is modulated to sustain reproductive effort, and show how spatial resource structure and nectar availability together shape movement decisions in male pollinators. LAY SUMMARYMale bumblebees keep searching for mates even when food is scarce, adjusting how they forage to conserve energy. Using 3D tracking in a controlled environment, we found that males reduce foraging effort but maintain reproductive behaviours. This shows how animals balance survival and reproduction in changing environments, offering new insights into pollinator behaviour and resilience.

animal behavior and cognition↗

bioRxiv2024

Trapline foraging by nectar-collecting hornets

Central place foraging bees, butterflies, birds and bats are known to develop routes in order to visit familiar plant resources in a stable and repeatable order called "traplines". Here we report a similar behaviour in a social wasp, the Japanese yellow hornet Vespa simillima. We monitored the foraging movements of individually marked wild hornets collecting sucrose solution on four artificial flowers placed in the field. After thirty foraging bouts, all the hornets had developed a repeatable flower visitation sequence. Using two different arrays of flowers, we show how hornets increase their foraging efficiency through time but do not always use the shortest path to visit all flowers, often favoring movements between nearest neighbor flowers over global path optimization. Our study adds nectar-foraging wasps to the growing list of animals developing traplines thereby opening new perspectives for comparative cognition research.

animal behavior and cognition↗

bioRxiv2018

Gap perception in bumblebees

A number of insects fly over long distances below the natural canopy where the physical environment is highly cluttered consisting of obstacles of varying shape, size and texture. While navigating within such environments animals need to perceive and disambiguate environmental features that might obstruct their flight. The most elemental aspect of aerial navigation through such environments is gap identification and passability evaluation. We used bumblebees to seek insights into the mechanisms used for gap identification when confronted with an obstacle in their flight path and behavioral compensations employed to assess gap properties. Initially, bumblebee foragers were trained to fly though an unobstructed flight tunnel that led to a foraging chamber. After the bees were familiar with this situation, we placed a wall containing a gap that unexpectedly obstructed the flight path on a return trip to the hive. The flight trajectories of the bees as they approached the obstacle wall and traversed the gap were analyzed in order to evaluate their behavior as a function of the distance between the gap and a background wall that was placed behind the gap. Bumblebees initially decelerate when confronted with an unexpected obstacle. Deceleration was first noticed when the obstacle subtended around 35{degrees} on the retina but also depended on the properties of the gap. Subsequently the bees gradually traded off their longitudinal velocity to lateral velocity and approached the gap increasing lateral displacements and lateral velocity. Bumblebees shaped their flight trajectory depending on the salience of the gap, in our case, indicated by the optic flow contrast between the region within the gap and on the obstacle, which increases with decreasing distance between the gap and the background wall. As the optic flow contrast decreased the bees spent increasing time moving laterally across the obstacles. During these repeated lateral maneuvers the bees are likely assessing gap geometry and passability.

animal behavior and cognition↗