Data for: Non-host species reduce parasite infection in a focal host species within experimental fish communities

<p class="MsoCommentText">The dilution effect describes the negative association between host biodiversity and the risk of infectious disease. Tests designed to understand the relative roles of host species richness, host species identity, and rates of exposure within experimental host communities would help resolve ongoing contention regarding the importance and generality of dilution effects. We exposed fathead minnows to infective larvae of the trematode, <i>Ornithodiplostomum ptychocheilus </i>in minnow-only containers and in mixed containers that held 1-3 other species of fish. Parasite infection was estimated as the numbers of encysted worms (i.e., brainworms) present in minnows following exposure. The results of exposure trials showed that non-minnow fish species were incompatible with <i>O. ptychocheilus</i> larvae. There was no reduction in mean brainworm counts in minnows in mixed containers with brook sticklebacks or longnose dace. In contrast, brainworm counts in minnows declined by 51% and 27% in mesocosms and aquaria, respectively, when they co-occurred with emerald shiners. Dilution within minnow + shiner containers may arise from shiner-induced alterations in minnow or parasite behaviours that reduced encounter rates between minnows and parasite larvae. Alternatively, shiners may act as parasite sinks for parasite larvae. These results highlight the role of host-species identity in the dilution effect. Our results also emphasize the complex and idiosyncratic effects of host community composition on rates of parasite infection within contemporary host communities that contain combinations of introduced and native species.</p>