2.1 Malaria parasites
Plasmodium relictum (lineage SGS1) is the most prevalent agent of avian malaria in Europe (Valkiunas, 2004). The parasite strain used in the first experiment was isolated from an infected Great tit (Parus major ) in Lausanne, Switzerland in June 2018. Since then, the parasite has been maintained by carrying out regular passages across a stock canaries (Serinus canaria ) through intraperitoneal injections (i.p) until the experiment (November 2018, Pigeault et al., 2015). The Plasmodium relictum strain (lineage SGS1) used in the second experiment was isolated two months before the experiment (January 2019) from an infected House sparrow (Passer domesticus ) captured in the field and passaged to naïve canaries by i.p.
Prior to the experimental infection, a small amount (ca.3-5 µL) of blood was collected from the medial metatarsal vein of each canaries to ensure that they were free from any previous haemosporidian infections. Three and four birds, for the experiment one and two respectively, were then inoculated by intraperitoneal injection of 100µL of an infected blood solution. Blood solution was constituted with a mixture of PBS and blood (ratio 1:1) sampled from 3 canaries infected with the parasite three weeks before the experiment. Ten days post-infection, bird parasitaemia (percentage of infected red blood cell) was estimated by visual quantification on blood smears (Valkiunas, 2004).