Ectoparasite activity during incubation increases microbial growth on avian eggs Tomás, G. Martín-Gálvez, David Ruiz Castellano, Cristina Ruiz-Rodríguez, Magdalena Peralta-Sánchez, Juan Manuel Martín-Vivaldi Martínez, Manuel Lorenzo Soler Cruz, Juan José ARISA Bacterial community Ectoparasite-host interactions Hatching success Niche construction Trans-shell transmission We thank Estefanía López for lab work, and Tomás Pérez-Contreras and Emilio Pagani-Núñez for facilitating collection of some of the flies used in manipulations. We also thank Ángela Martínez-García for help with management of ARISA data and Natalia Juárez and Deseada Parejo for the pictures of owls and roller clutches, respectively. We appreciate the comments provided by Dr. Adèle Mennerat and five anonymous referees on earlier versions of the manuscript. All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. While direct detrimental effects of parasites on hosts are relatively well documented, other more subtle but potentially important effects of parasitism are yet unexplored. Biological activity of ectoparasites, apart from skin injuries and blood-feeding, often results in blood remains, or parasite faeces that accumulate and modify the host environment. In this way, ectoparasite activities and remains may increase nutrient availability that may favour colonization and growth of microorganisms including potential pathogens. Here, by the experimental addition of hematophagous flies (Carnus hemapterus, a common ectoparasite of birds) to nests of spotless starlings Sturnus unicolor during incubation, we explore this possible side effect of parasitism which has rarely, if ever, been investigated. Results show that faeces and blood remains from parasitic flies on spotless starling eggshells at the end of incubation were more abundant in experimental than in control nests. Moreover, eggshell bacterial loads of different groups of cultivable bacteria including potential pathogens, as well as species richness of bacteria in terms of Operational Taxonomic Units (OTUs), were also higher in experimental nests. Finally, we also found evidence of a link between eggshell bacterial loads and increased embryo mortality, which provides indirect support for a bacterial-mediated negative effect of ectoparasitism on host offspring. Trans-shell bacterial infection might be one of the main causes of embryo death and, consequently, this hitherto unnoticed indirect effect of ectoparasitism might be widespread in nature and could affect our understanding of ecology and evolution of host-parasite interactions 2019-12-04T07:54:05Z 2019-12-04T07:54:05Z 2018-01-13 info:eu-repo/semantics/article Microbial Ecology (2018) http://hdl.handle.net/10481/58162 10.1007/s00248-017-1140-6 eng https://doi.org/10.1007/s00248-017-1140-6 http://rdcu.be/EGww http://creativecommons.org/licenses/by-nc-nd/3.0/es/ info:eu-repo/semantics/openAccess Atribución-NoComercial-SinDerivadas 3.0 España Springer