Ecology of ectoparasites and vector-borne diseases in bats and birds

Mosquitoes are responsible for transmitting many pathogens (i.e. viruses, bacteria, protozoans, and nematodes) to humans and other vertebrates, causing severe diseases, such as malaria, encephalitis, filariasis, yellow fever, and dengue (Becker et al. 2010; Brugman et al. 2018). Malaria is considered one of the most important scourges that humanity has faced during its history, being responsible every year for many deaths worldwide (WHO 2020). This vector-borne disease is caused by the protozoan parasite Plasmodium, whose life cycle involves an obligatory period of replication and development into vertebrate and invertebrate hosts, generating considerable attention to the role of hosts’ variability in shaping Plasmodium transmission (Baird 2009; Becker et al. 2010). Plasmodium infection could alter mosquito fecundity, longevity, survival, host-seeking behavior, and preferential host attraction (Hurd 2003; Lalubin et al. 2014; Stanczyk et al. 2017). Moreover, the physiological changes induced by the ingestion of Plasmodium-infected blood meal could affect or prevent parasite development due to the activation of several immune effector mechanisms (Dimopoulos et al. 1998; Luckhart et al. 1998; Colasanti et al. 2002; Rivero 2006). Thus, the study of the mosquito immune response to infection by Plasmodium may be a key to finding ways to interrupt or control malaria transmission (Tripet 2009).

During my Ph.D., I would like to understand the dynamics of the interaction between Plasmodium-mosquito, especially the mosquito immune response to infection by Plasmodium because both parasites and hosts have applied pressure on each other to evolve and generate mechanisms to evade host immunity and to remove parasites during an infection, respectively. In this line, we would like to explore the effect of different environmental stresses at larval (i.e. food deprivation, larval competition) and adult stage (i.e. multiple blood meals with infected and non-infected blood, ingestion of antiparasitic medication in blood or sugar) on (i) the mosquito immunologic response to Plasmodium infection, (ii) parasite development, (iii) mosquito microbiota (Wolbachia), and (iv) several mosquito life history traits that might impact the transmission of this pathogen (vectorial capacity). To test this, experiments will be conducted with a natural system consisting of the avian malaria parasite Plasmodium relictum (lineage pSGS1), which is the most prevalent agent of avian malaria in Europe, and its vector in the wild, the mosquito Culex pipiens (Valkiunas 2004; Glaizot et al. 2012).