Differences in specificity, development time and virulence between two acanthocephalan parasites, infecting two cryptic species of *Gammarus fossarum*use asterix (*) to get italics
Alexandre Bauer, Lucie Develay Nguyen, Sébastien Motreuil, Maria Teixeira, Nelly Debrosse, Thierry RigaudPlease use the format "First name initials family name" as in "Marie S. Curie, Niels H. D. Bohr, Albert Einstein, John R. R. Tolkien, Donna T. Strickland"
<p style="text-align: justify;">Multi-host parasites can exploit various host species that differ in abundance and susceptibility to infection, which will contribute unequally to their transmission and fitness. Several species of acanthocephalan manipulative parasites (among which <em>Pomphorhynchus laevis</em> and <em>P. tereticollis</em>) use various amphipod species of the genus Gammarus as intermediate hosts. Many <em>Gammarus pulex</em> and <em>G. fossarum</em> cryptic lineages are living in sympatry in European rivers, questioning the spectrum of intermediate hosts that acanthocephalans can use, and their relative contribution to their life cycles. In this work, the respective roles of parasites species (<em>P. laevis</em> and, for the first time, P<em>. tereticollis</em>) and sympatric host cryptic species (the <em>G. fossarum</em> species complex) were studied experimentally on two traits: host susceptibility to infection and parasite virulence. Differences were found, both in terms of infectivity and virulence, between the cryptic hosts and between the two parasite species. We confirm that these acanthocephalans, previously considered as generalists, show specificities among their sympatric hosts. Differences in field prevalence and susceptibility after experimental exposures were more pronounced between cryptic <em>G. fossarum </em>species for <em>P. tereticollis</em> than for <em>P. laevis</em>. The mortality of infected individuals increased significantly after several weeks of development of both parasite species. <em>P. tereticollis</em> was less virulent than <em>P. laevis</em>, perhaps due to differences in host exploitation, since we evidenced that P. tereticollis had a much slower growth rate.</p>
experimental infection, Gammarus fossarum, Gammarus pulex, host specificity, infectivity, multi-host parasite, Pomphorhynchus laevis, Pomphorhynchus tereticollis, prevalence
Ecology of hosts, infectious agents, or vectors, Evolution of hosts, infectious agents, or vectors, Interactions between hosts and infectious agents/vectors, Molecular genetics of hosts, infectious agents, or vectors, Parasites, Resistance/Virulence/Tolerance, Taxonomy of hosts, infectious agents, or vectors