Population Ecology


, Volume 142, Issue 4, pp 541-545

First online:

Malarial parasites decrease reproductive success: an experimental study in a passerine bird

  • Alfonso MarzalAffiliated withDepartamento de Biología Animal, Universidad de Extremadura Email author 
  • , Florentino de LopeAffiliated withDepartamento de Biología Animal, Universidad de Extremadura
  • , Carlos NavarroAffiliated withDepartamento de Biología Animal, Universidad de Extremadura
  • , Anders Pape MøllerAffiliated withLaboratoire de Parasitologie Evolutive, CNRS UMR 7103, Université Pierre et Marie Curie

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Malarial parasites are supposed to have strong negative fitness consequences for their hosts, but relatively little evidence supports this claim due to the difficulty of experimentally testing this. We experimentally reduced levels of infection with the blood parasite Haemoproteus prognei in its host the house martin Delichon urbica, by randomly treating adults with primaquine or a control treatment. Treated birds had significantly fewer parasites than controls. The primaquine treatment increased clutch size by 18%; hatching was 39% higher and fledging 42% higher. There were no effects of treatment on quality of offspring, measured in terms of tarsus length, body mass, haematocrit or T-cell-mediated immune response. These findings demonstrate that malarial parasites can have dramatic effects on clutch size and other demographic variables, potentially influencing the evolution of clutch size, but also the population dynamics of heavily infected populations of birds.


Blood parasites Delichon urbica Haematozoa Primaquine Reproductive success