title: Ectoparasitism and stress hormones: strategy of host exploitation, common host-parasite history and energetics matter.
abstract: Parasites are thought to have numerous negative effects on their hosts. These negative effects may be associated with stress in a host. We evaluated the effects of four species of flea ectoparasites (Parapulex chephrenis, Synosternus cleopatrae, Xenopsylla conformis and Xenopsylla ramesis) on non-specific responses of eight species of rodents (Meriones crassus, Gerbillus dasyurus, Gerbillus andersoni, Gerbillus pyramidum, Gerbillus nanus, Acomys cahirinus, Acomys russatus and Mesocricetus auratus) and measured faecal glucocorticoid metabolites concentrations (FGMC) produced by the hosts. We found no effect of body mass of an individual rodent on FGMCs. Parasitism by fleas with a 'stay on the host body' exploitation strategy was associated with higher host FGMCs than parasitism by fleas that spent most of their life 'off-host'. FGMCs among rodents infested by the same flea species were correlated positively with the phylogenetic distance of a given rodent from the principal host of this flea; changes in FGMCs were lower in the host species more closely related to the flea's principal host. Changes in FMGCs of a host while parasitized were correlated with a host's change in body mass, where hosts that lost more body mass had higher FGMCs. Our results suggest that ectoparasitism can be stressful to their hosts. However, the occurrence of parasite-induced stress seems to depend on the identity of both host and parasite species and the evolutionary history of a host-parasite association. To our knowledge, this is the first multispecies study to evaluate the effect of ectoparasites on glucocorticoid hormones in small mammals.
authors.affiliation: Department of Biology, Indiana State University, 200 N. 7th St., Terre Haute, IN 47809, USA.|Mitrani Department of Desert Ecology, Swiss Institute for Dryland Environmental and Energy Research, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel.|Department of Life and Physical Science, Ivy Tech Community College Wabash Valley, 8000 S. Education Drive, Terre Haute, IN 47802, USA.
authors.forename: Justin R
authors.initials: JR
authors.lastname: St Juliana
authors.affiliation: Wyler Department of Dryland Agriculture, French Associates Institute for Agriculture and Biotechnology of Drylands Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel.
authors.forename: Irina S
authors.initials: IS
authors.lastname: Khokhlova
authors.affiliation: Department of Conservation Science, Chicago Zoological Society/Brookfield Zoo, 3300 Golf Road, Brookfield, IL 60513, USA.|Conservation Research Division, Oregon Zoo, 4001 SW Canyon Rd., Portland, OR 97221, USA.
authors.forename: Nadja
authors.initials: N
authors.lastname: Wielebnowski
authors.affiliation: Mitrani Department of Desert Ecology, Swiss Institute for Dryland Environmental and Energy Research, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel.
authors.forename: Burt P
authors.initials: BP
authors.lastname: Kotler
authors.affiliation: Mitrani Department of Desert Ecology, Swiss Institute for Dryland Environmental and Energy Research, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel.
authors.forename: Boris R
authors.initials: BR
authors.lastname: Krasnov
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001835:Body Weight; D005243:Feces / Q000737:chemistry*; D005938:Glucocorticoids / Q000032:analysis*; D058507:Host Specificity; D006790:Host-Parasite Interactions; D009115:Muridae / Q000469:parasitology* / Q000502:physiology; D010802:Phylogeny; D005423:Siphonaptera / Q000502:physiology*; D013312:Stress, Physiological
chemical_list: D005938:Glucocorticoids
keywords: corticosterone; faecal glucocorticoid metabolites; fleas; parasitism; principal host; rodents; stress