Table 1.

Description of the different types of social parasitism.

types of social parasitism	description	examples	references
brood parasitism: inquilinism	Workers or queens enter con- or heterospecific nests, reproduce and exploit the hosts' workforce for brood rearing. This form of parasitism can be temporary, when social parasites depend on hosts only for colony foundation, or permanent, when parasites only produce sexuals, but no or few workers. Thus, they continuously depend on host workers to perform all necessary tasks. In bumblebees, reproductive parasitism is done by both workers (also called ‘egg dumping’), e.g. in Bombus terrestris, and queens, e.g. in B. norvegicus. Brood parasitism can be facultative, e.g. in Melipona stingless bees, Apis mellifera and Vespula vulgaris workers, or obligate, e.g. in cuckoo bumblebees.	ants, bumblebees, stingless bees, honeybees, wasps	[13,16–18,28–38]
brood parasitism: dulosis or ‘slave-making’	Queens establish a new colony by invading a host nest and killing or expelling adults. The host brood, once developed, raises the parasite's own offspring. Slaves are replenished by workers stealing brood from nearby host nests.	ants	[39–50]
cleptoparasitism: raiding, agro-predation and xenobiosis	The stealing of food, building material or other valuable resources from a colony. One particular case is ‘agro-predation’, where fungal crops or symbiotic livestock are stolen. Stealing can happen by force, e.g. in Lestrimelitta robber bees or by stealth, e.g. in Ectatomma ants. Another example is xenobiosis, where parasite queen and workers live in the same or an adjacent nest and consume the food of their host. The brood of host and parasite are kept apart. We consider cleptoparasitism a form of social parasitism if parasites take advantage of the social lifestyle of their hosts, e.g. by raiding a colony's resources.	ants, honeybees, stingless bees, wasps	[14,15,51–57]
usurpation	Colonies are evicted from their nest by another colony, either from the same species, as in honeybees, or by another species, as in stingless bees and ants.	ants, honeybees, stingless bees, thrips	[13,15,58–60]