Insect predation reduces the abundance of a nidicolous ectoparasite

• Published in: Ecological entomology 2021-08, Vol.46 (4), p.988-998
• Main Authors: Salido, Angela, Veiga, Jesús, Reyes‐López, Joaquín L., Nieves‐Aldrey, Jose L., Valera, Francisco
• Format: Article
• Language: English
• Subjects: Abundance; Animal behavior; Ants; Boxes; Breeding seasons; Carnus hemapterus; Chartocerus conjugalis; Ectoparasites; Food chains; Food webs; Host-parasite interactions; Insects; interspecific interactions; Natural enemies; Nest boxes; Parasites; parasitic load; parasitoid; Predation; Predators; Prey; Pupae; Seasons
• ISSN: 0307-6946; 1365-2311
• DOI: 10.1111/een.13036

1. Parasites are one of the main actors in host–parasite interactions. Still, their role as a prey and the related consequences for such interactions and in other respects, such as food webs, are frequently overlooked. 2. This paper analyses predation pressure on a ubiquitous avian ectoparasitic fly, Carnus hemapterus, identifies their main natural enemies and quantifies their relative effect on the abundance of the parasite. Also, the effect of nest‐site type on their main enemies' predation pressure was analysed. 3. Several ant species were found in the nest boxes of the host species, the European roller (Coracias garrulus), during the breeding season and preyed upon adult and larval stages of Carnus. 4. Ants were also the putative predators of carnid pupae after the breeding season, when significant reduction (on average, by half) in the abundance of carnid pupae occurred in 75% of nest boxes within few months. 5. Carnid pupae are also reported here, for the first time, to be parasitised by the parasitoid wasp Chartocerus conjugalis, whose prevalence was around 21%. 6. Nest‐site type had no clear effect on the predation rate of carnid pupae after the breeding season. 7. It was concluded that predation is an important factor regulating the abundance of ectoparasites, and thus, it may influence the outcome of host–parasite relationships. Ants visiting nest boxes prey upon adult and larval stages of a bird ectoparasite and are the putative predators of diapausing pupae, halving their abundance within few months. A parasitoid wasp, Chartocerus conjugalis, is identified for the first time as a frequent parasitoid of the ectoparasite Carnus hemapterus. Predation is an important factor regulating the abundance of the ectoparasite and, thus, influencing the outcome of host–parasite relationship.