Social parasite pressure affects brood discrimination of host species in Temnothorax ants

► We compared brood tolerance of slave-making ants' host and nonhost species. ► Host species' colonies were less tolerant to alien pupae than nonhost species. ► Enslaved workers were more tolerant to alien pupae than free-living conspecifics. ► Enslaved workers groomed alien parasite more than alien conspecific brood. ► Host-parasite interaction may shape social recognition mechanisms in ants.