Social Parasitism in Hymenopteran Insects

Social parasitism in Hymenoptera encompasses a spectrum of strategies by which one insect exploits the social structure and brood‐care systems of another. In ants, bees and wasps, parasitic species may found colonies by temporarily co-opting host workers, permanently usurping nests, or conducting slave-making raids to capture brood. Across ants alone, obligate inquiline parasites—species that produce no worker caste—have arisen independently in dozens of lineages, often in close phylogenetic proximity to their hosts in accordance with Emery’s rule. Evolutionary pathways to parasitism include sympatric divergence within polygynous colonies, host-shift events and incremental behavioural adaptations from free-living ancestors. These interactions shape colony fitness, community structure and co-evolutionary dynamics, with implications for biodiversity conservation, biological control and the management of invasive pests.

Research from Nature Portfolio

Recent meta-analyses integrating social-structure data and ant phylogenies have revealed a significant over-representation of polygynous species among hosts of inquiline parasites. By applying phylogenetic correction across multiple ant genera, this work demonstrates that multiple‐queen systems and associated social plasticity may facilitate the origin of workerless parasitic lineages via intra-specific speciation or opportunistic acceptance of alien queens. These findings support parallel, repeated evolutions of inquiline behaviour in disparate ant clades, underscoring the role of colony organisation in promoting social parasitism.

Social Parasitism in Hymenopteran Insects publication trend

The graph below shows the total number of articles in social parasitism in hymenopteran insects across all publications each year (not limited to Nature Index journals).

Technical terms

Inquiline: A workerless parasite species that depends entirely on the host colony’s workers for brood care and survival.

Temporary parasitism: A colony-founding strategy in which a parasitic queen exploits host workers to establish her own brood before transitioning to independent reproduction or host replacement.

Dulosis: Also known as slave-making; a parasitic strategy in which the parasite conducts raids on host nests to seize brood and rear them as workers.

Polygyny: The presence of multiple reproductive queens within a single colony, often linked to increased social complexity and vulnerability to parasitic exploitation.

Emery’s rule: An empirical observation that social parasites tend to be closely related to their hosts, suggesting common ancestry or recent divergence.

References

1. Multi-queen breeding is associated with the origin of inquiline social parasitism in ants. Scientific Reports (2022).
2. Phylogenomics of palearctic Formica species suggests a single origin of temporary parasitism and gives insights to the evolutionary pathway toward slave-making behaviour. BMC Ecology and Evolution (2018).
3. Phylogenetic tests reject Emery's rule in the evolution of social parasitism in yellowjackets and hornets (Hymenoptera: Vespidae, Vespinae). Royal Society Open Science (2015).