Avian immune responses to ectoparasites: a serological survey of ectoparasite-specific antibodies in birds in western Nebraska

Birds serve as reservoirs for at least 10 arthropod borne viruses of wildlife and human concern (e.g. West Nile virus, Western Equine Encephalitis) and greater knowledge of the immune system dynamics of avian hosts and their disease vectors will have obvious economic benefits to agricultural, wildlife and human health interests. The more we begin to understand the host-vectorpathogen interactions that contribute to the emergence and transmission of arthropod borne diseases, we can better predict where outbreaks might occur and whose health and economic interests will be affected. Arthropod vectors (ectoparasites) exert strong direct selection pressures on their avian hosts by decreasing nestling survival, reducing future reproductive events and host lifespan. Levels of ectoparasites are known to vary widely across species with different life history strategies, and also across different life history stages of the same species. For example, colonial nesting birds (e.g. swallows and martins) have been shown to have enhanced levels of ectoparasites compared to non-colonial birds (e.g. sparrows) and nestlings are known to be highly susceptible to ectoparasites in multiple avian species. However, no studies have been performed that have investigated how immune responses to arthropod disease vectors variy across avian species with different life history characteristics (i.e. native vs. invasive), or the role that arthropod salivary proteins play in avian arbovirus disease ecology. The specific objectives of this proposal are aimed at quantifying the immune responses of free-living cliff swallows and house sparrows to the salivary proteins of an ecologically relevant ectoparasite, the swallow bug. Additionally, I will characterize the swallow bug-specific immune responses of nestling, juvenile and adult birds following experimental inoculation with swallow bug salivary proteins. To my knowledge, this will be the first study to document age-dependent immune responses of native and invasive avian hosts in response to ectoparasites, and will increase our knowledge of the immunomodulatory effects of vector salivary proteins on avian hosts.