Abstract
The Hamilton and Zuk hypothesis on haemoparasite-mediated sexual selection and certain studies of reproductive costs are based on the assumption that avian blood parasite infections are detrimental to their hosts. However, there is no experimental evidence demonstrating harmful effects of blood parasites on fitness in wild populations, it even having been suggested that they may be non-pathogenic. Only an experimental manipulation of natural blood parasite loads may reveal their harmful effects. In this field experiment we reduced through medication the intensity of infection by Haemoproteus majoris and the prevalence of infection by Leucocytoazoon majoris in blue tits (Parus caeruleus), and demonstrated detrimental effects of natural levels of infection by these common parasite species on host reproductive success and condition. The fact that some of the costs of infection were paid by offspring indicates that blood parasites reduce parental working capacity while feeding nestlings. Medicated females may be able to devote more resources to parental care through being released from the drain imposed upon them by parasites and/or through a reduced allocation to an immune response. Therefore, this work adds support to previous findings relating hosts' life-history traits and haematozoan infections.
Full Text
The Full Text of this article is available as a PDF (161.3 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Atkinson C. T., Forrester D. J., Greiner E. C. Pathogenicity of Haemoproteus meleagridis (Haemosporina: Haemoproteidae) in experimentally infected domestic turkeys. J Parasitol. 1988 Apr;74(2):228–239. [PubMed] [Google Scholar]
- Graczyk T. K., Shaw M. L., Cranfield M. R., Beall F. B. Hematologic characteristics of avian malaria cases in African black-footed penguins (Spheniscus demersus) during the first outdoor exposure season. J Parasitol. 1994 Apr;80(2):302–308. [PubMed] [Google Scholar]
- Hamilton W. D., Zuk M. Heritable true fitness and bright birds: a role for parasites? Science. 1982 Oct 22;218(4570):384–387. doi: 10.1126/science.7123238. [DOI] [PubMed] [Google Scholar]
- Mayorga P., Deharo E., Landau I., Couarraze G. Preliminary evaluation of primaquine activity on rodent malaria model after transdermal administration. Parasite. 1997 Mar;4(1):87–90. doi: 10.1051/parasite/1997041087. [DOI] [PubMed] [Google Scholar]
- Merino S., Potti J., Fargallo J. A. Blood parasites of passerine birds from central Spain. J Wildl Dis. 1997 Jul;33(3):638–641. doi: 10.7589/0090-3558-33.3.638. [DOI] [PubMed] [Google Scholar]
- Merino S., Potti J., Moreno J. Maternal effort mediates the prevalence of trypanosomes in the offspring of a passerine bird. Proc Natl Acad Sci U S A. 1996 Jun 11;93(12):5726–5730. doi: 10.1073/pnas.93.12.5726. [DOI] [PMC free article] [PubMed] [Google Scholar]