Biology subjects

Mahot-Castaing, B.

Publications and source records attributed to Mahot-Castaing, B..

3 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↗

bioRxiv2024

Invasive Vespa velutina nigrithorax hornets are more susceptible to entomopathogenic fungus than two other hymenopteran species, the wasp Vespa vulgaris and the bumblebee Bombus terrestris.

Entomopathogenic fungi are commonly used as biological control agents. Recently, a strain of Metarhizium robertsii (Sorokin, 1883) (Hypocreales: Clavicipitaceae) collected in France was identified as a good candidate for controlling invasive populations of yellow-legged hornet, Vespa velutina nigrithorax (Buysson, 1905) (Hymenoptera: Vespidae) in Europe. Since M. robertsii is generalist, its use as bioagent could be damaging for non-targeted species. Here, we compared the lethal effects of three concentrations of this M. robertsii strain on the invasive hornet and two non-targeted species commonly found in Europe, the common wasp Vespa vulgaris (Linnaeus, 1758) (Hymenoptera: Vespidae) and the buff-tailed bumblebee Bombus terrestris (Linnaeus, 1758) (Hymenoptera: Apidae). Exposure to M. robertsii spores altered the survival of all three species but at different degrees. Hornets had consistently lower survival, even under low concentrations of spores, when compared to wasps and bumblebees. Such lower susceptibility of beneficial Hymenoptera is encouraging in the perspectives of using M. robertsii as biocontrol agent against invasive hornets.

animal behavior and cognition↗

bioRxiv2024

Is this scenery worth exploring? Insight into the visual encoding of navigating ants.

Solitary foraging insects like desert ants rely heavily on vision for navigation. While ants can learn visual scenes, it is unclear what cues they use to decide if a scene is worth exploring at the first place. To investigate this, we recorded the motor behavior of Cataglyphis velox ants navigating in a virtual reality set-up and measured their lateral oscillations in response to various unfamiliar visual scenes under both closed-loop and open-loop conditions. In naturalistic-looking panorama, ants display regular oscillations as observed outdoors, allowing them to efficiently scan the scenery. Manipulations of the virtual environment revealed distinct functions served by dynamic and static cues. Dynamic cues, mainly rotational optic flow, regulated the amplitude of oscillations but not their regularity. Conversely, static cues had little impact on the amplitude but were essential for producing regular oscillations. Regularity of oscillations decreased in scenes with only horizontal, only vertical or no edges but was restored in scenes with both edge types together. The actual number of edges, the visual pattern heterogeneity across azimuths, the light intensity or the relative elevation of brighter regions did not affect oscillations. We conclude that ants use a simple but functional heuristic to determine if the visual world is worth exploring, relying on the presence of at least two different edge orientations in the scene. Summary statementUsing a virtual reality setup, we reveal that ants rely on a heuristic to trigger visual exploration in an unfamiliar scene. The simultaneous presence of vertical and horizontal edges is necessary and sufficient for the ants to produce lateral oscillations and scan the scene.

animal behavior and cognition↗