Meeting Abstract
In cavity-nesting songbirds, blood-feeding ectoparasite infestations can induce developmental trade-offs among somatic growth, physiological maturation and immune function. To grow and reproduce, ectoparasites require blood meals, which may be costly to host chicks, yet few studies have assessed which consequences of blood meals might induce developmental trade-offs. Previous research in European starlings (Sturnus vulgaris) suggests that Northern fowl mite (Ornithonyssus sylviarum) infestations produce effects on nestling phenotypes that are not simply mimicked by experimental blood loss. Perhaps mites also induce energetically costly acute phase responses in host chicks, characterized, in part, by increased proinflammatory cytokine production. We experimentally manipulated Northern fowl mite abundance and experimental blood loss in starling chicks and assessed chick survival, somatic growth, physiological maturation, and plasma concentration of the proinflammatory cytokine interleukin 6 (IL-6), to assess whether inflammation intensity covaries with these other variables. Nests were assigned to one of three treatments: permethrin-induced mite reduction, experimental blood loss, or mite enhancement. We assessed somatic growth of chicks at 5, 10 and 15 days of age. At these ages, blood was also collected to assess hematocrit, hemoglobin concentration, and inflammation via an IL-6 enzyme immunoassay. In chicks from the experimental blood loss group, additional blood was also collected as part of their experimental treatment. Preliminary results suggest that, relative to the other treatments, mite enhancement produced lighter chicks, and slowed physiological development. These data will be presented and discussed along with data on plasma IL-6 concentrations and nestling survival.
