Insectes Sociaux

Friedel, A.; Quezada-Euán, J. J. G.; Paxton, R. J.; Soro, A.

2024 Insectes Sociaux

doi: 10.1007/s00040-024-01000-2

Natural enemies impose a selective pressure on solitary insects that may favour the evolution of sociality. In the socially polymorphic orchid bee Euglossa viridissima, females found nests solitarily and provision a first batch of brood. After brood maturity, a nest can remain solitary (all offspring disperse) or become social, when one or more subordinate daughters forage for nesting material and brood provisions for the dominant mother. Solitary females leave their nest unguarded when foraging whilst a female in a social nest can guard the nest while nestmates are foraging. By observing solitary and social nests, we found that subordinate foragers in social nests undertook longer provisioning trips than solitary females. The presence of a guarding female in a social nest protected the nest against intrusion, possibly favouring longer provisioning trips. Moreover, the frequency of successful attempts by intruders to enter nests was significantly lower in social nests. Our results provide strong support for the parasite defence hypothesis for the evolution of social behaviour.

Meunier, J.

2024 Insectes Sociaux

doi: 10.1007/s00040-024-01001-1

Masoni, A.; Castellucci, F.; Piccinini, A.; Greco, C.; Balzani, P.; Frizzi, F.; Mattucci, F.; Giangregorio, P.; Guariento, E.; Zaccaroni, M.; Santini, G.; Luchetti, A.

2024 Insectes Sociaux

doi: 10.1007/s00040-024-00999-8

The phylogeography and demographical history of Italian Formica pratensis populations were examined and compared with the Eurasian-wide dataset available for this species and the other red wood ant species Formica lugubris. Forty-eight workers belonging to eight populations from both Alps and Apennines were analysed sequencing a 1.5-kilobase mitochondrial DNA fragment, including the cytochrome b gene and part of the NADH dehydrogenase subunit 6 gene. A total of 127 sequences were screened, scoring 53 different haplotypes amongst all specimens, with five new haplotypes discovered in the Italian populations. All the Italian haplotypes clustered in a monophyletic clade, underlining a clear phylogeographical separation of this group from the other Eurasian groups and suggesting a glacial separate forest refugia and different post-glacial colonisation patterns. The haplotypes from the Alps and the Apennines showed a high genetic proximity, pointing out an ancient (Pleistocene) wide distribution of this species across all these areas and common ancestral lineages. No shared haplotypes were scored between Northern and Central Apennine populations, but the low inter-population genetic distance indicated similar post-glacial selective processes acting on these groups. The diversity we recorded may be influenced by the actual fragmentation of F. pratensis populations across its entire Eurasian range, and by the limited geographical origin and sample dimension of the dataset analysed. Future studies with a more extensive sampling in the Alps and Eastern Europe are needed to confirm our result.