Hemoparasites and immunological parameters in Snow Bunting (Plectrophenax nivalis) nestlings

Abstract

Knowledge on hemoparasites and immunological parameters in wild birds with Arctic distribution is limited. In this study, we chose the Snow Bunting (Plectrophenax nivalis) as model species to address this issue. Using nestlings, we aimed at (i) detecting hemoparasites with vector-borne transmission (via microscopic and molecular methods) and nest-dwelling ectoparasites and at (ii) exploring the relationship between several immunological parameters and parasitism. Nestlings were infected by Lankesterella parasites but hemoparasites of the genera Plasmodium, Haemoproteus, Leucocytozoon, Trypanosoma, Hepatozoon or Babesia were not found. This result may indicate the lack of suitable dipteran vectors or the inability of haemosporidians to reproduce in the Arctic region. Inflammation in response to the phytohaemagglutinin (PHA) injection was negatively related to infection by Lankesterella and positively related to weight gain in nestlings. The number of leukocytes and IgG level were not related to infection or PHA response, although the relationship between IgG level and PHA immune response was marginally significant. Besides, nestlings reared in mite-infected nests showed higher IgG level than those reared in mite-free nests. Taken together, (i) the positive relationship between PHA response/weight gain and PHA response/IgG level could reflect the nestlings’ nutritional status; and (ii) the higher IgG level in nestlings reared in mite-infected nests may be the result of a specific immune response to mite antigens. Different parasites may alter distinct immunological parameters in birds breeding under extreme weather conditions.