In eusocial insects, the division of labour means, among other things, that only few individuals forage for the entire colony. The survival of the colony depends on their efficiency in fitting the nutritional needs of all its members. We aimed at measuring the network topology and at understanding the role and centrality of each caste in this network and as a consequence on food dissemination across castes. We constructed the trophallaxis networks from 34 food exchanges experiments-in black garden ants (Lasius niger). We tested the influence of brood and colony size on: (i) global indices at the network level, i.e. efficiency, resilience, centralisation and modularity; (ii) the individuals' values of degree, strength, betweenness and clustering coefficient. Network resilience, which is the ratio between global efficiency and centralisation, is stable with colony size but increases with the presence of a brood, in order to possibly respond to the needs of larvae. Individual metrics highlighted the major role of foragers in food dissemination. In addition, a hierarchical clustering analysis suggested that some trophallactic network against resource quality.

Of all the calls made by non-human primates, the function of short-distance contact calls has largely remained to be determined. These calls are the most frequent in the repertoire and are most often exchanged between individuals in a non-random way. To our knowledge, no study has ever examined how vocal exchanges are structured in red-capped mangabeys (Cercocebus torquatus), a semi-terrestrial monkey living in the African forest with a complex semi-tolerant/semi-despotic social system. Our goal was to assess the organization of contact call exchanges in this species and their relationship with individual and social factors such as age, affinity, and hierarchy. Therefore, we observed several captive groups of red-capped mangabeys and collected data on vocal behavior, as well as grooming, agonistic behavior and spatial proximity. We defined a vocal exchange in this species as a series of contact calls made by two or more individuals within a maximum inter-caller interval of two seconds. At the individual level, the higher the individual's hierarchical rank, the less they initiated exchanges.Furthermore, the most socially integrated individuals had a longer average response time than the less integrated ones. At the dyadic level, preferred exchange partners were individuals often observed near one other or individuals most distant in age. Also, the further apart two individuals were in the dominance hierarchy, the shorter the response time. Our results support both the social bonding hypothesis and a modulating key role of the dominance hierarchy on the social use of contact calls, which is in line with the social style of this species.

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