Pollinator diversity and host specificity in threatened <i>Encephalartos</i> cycads and their implications for co‐extinction and species recovery

Abstract The highly threatened African cycad genus Encephalartos faces severe threats such as habitat loss and poaching. In addition, the lack of sexual recruitment due to the absence of pollinators (pollinator collapse) has emerged as another major threat. Experimental studies have identified three key Encephalartos pollinator groups: Porthetes (Coleoptera: Curculionidae), undescribed erotylid species (Coleoptera: Erotylidae) and Metacucujus (Coleoptera: Boganiidae). This study investigates the diversity and host specificity of Encephalartos pollinators to determine their vulnerability to collapse and potential for recovery. Across 28 Encephalartos species in southern and eastern Africa, we recorded 39 putative pollinator taxa, most showing high host specificity, with 19 species occurring on a single host. To identify potential traits affecting pollinator host specificity for further study, we analysed the influence of host phylogeny, cone volatile profiles, cone colour and cone phenology using distance‐based redundancy analysis. Host relatedness and cone volatile emissions explained the largest proportion of variation in pollinator assemblages, while cone colour and phenology contributed comparatively less. These relationships should be interpreted cautiously since analyses were based on total cone volatile composition and human‐perceived cone colour, and may not directly reflect the specific compounds or perceptual cues used by pollinators. Records of pollinators visiting novel host plants in cultivation suggest that host use may sometimes extend beyond observed wild associations, potentially reflecting pre‐adapted recognition mechanisms linked to cone traits similar to those of their wild hosts, or previously existing host associations that have been lost in the wild. These possibilities require further behavioural and ecological testing. Our findings confirm reports of pollinator collapse in at least 13 Encephalartos species, emphasizing the urgent need to consider pollinators in cycad conservation strategies. Future research should prioritize ecological and behavioural studies of cue perception and attraction, refinement of pollinator taxonomy, and evaluation of whether ecologically compatible pollinator species could be used to restore pollination in Encephalartos species where pollinator mutualists have been lost. Read the free Plain Language Summary for this article on the Journal blog.