Callows have their own odour but not for long: Fast acquisition of the chemical signature in the yellow-legged hornet, Vespa velutina nigrithorax

In eusocial insects, the discrimination between conspecifics and intruders is essential for the functioning of most insect societies. This capacity mediated by pheromones, and in particular by Cuticular Hydrocarbon Compounds (CHCs) is the main mechanism of social nestmate recognition which can include heritable cues, as well as acquired cues from nestmates and/or their environment. In this study, we analysed the acquisition of the chemical signature of callows over time, compared to nestmate workers and their nest materials in the invasive hornet Vespa velutina nigrithorax. We show that callows present their own chemical signature, different from both the oldest individuals and nest materials. Interestingly, this chemical signature evolves rapidly, the first two days after emergence, and is not influenced by the presence of a chemical template (workers and/or nests) in laboratory conditions. Moreover, quantities of branched alkanes increased with age. All these results suggest that the chemical signature in V. velutina nigrithorax is probably more influenced by some parameters like physiological processes or genetic factors.