Meeting Abstract

S4-1.6  Jan. 5  Ecological stoichiometry of host-parasite interactions: effects of elemental food quality on host responses to infectious disease FROST, P.C.*; EBERT, D.; SMITH, V.H.; Trent University, Canada; Universitšt Basel, Switzerland; University of Kansas, USA paulfrost@trentu.ca

The life-history of host organisms can be significantly altered by both their nutrition and by infectious disease. For example, life history characteristics of a freshwater crustacean, Daphnia magna, responds strongly to elemental food quality and to infection by the spore-forming bacterium, Pasteuria ramosa. Despite these singular effects having received considerable study, the interactive effects of infectious disease and diet quality on organismal life-history characteristics remain largely unstudied. We examined how life-history characteristics in Daphnia magna respond to bacterial infection in animals consuming different elemental food qualities (i.e., different P content). We provided the Daphnia (infected and uninfected) with high food quantity and monitored for growth rates, reproduction, and survival over 24 days of the experiment. After six days, bacterial infection had no significant effect on daphnid growth rates regardless of their dietary P. Similar to previous studies, infected Daphnia consuming high food quality typically produced one or two broods before losing their reproductive capabilities. On the other hand, infected Daphnia grown at mildly P-limiting conditions showed extended periods of reproduction or reversed bacterial-induced sterilization. Infected Daphnia consuming low P food showed higher mortality rates compared to uninfected controls. In contrast, no differences in mortality rates were found between infected and uninfected Daphnia consuming P-rich food. It thus appears that bacterially-mediated changes in key life-history characteristics (involving mortality and reproduction) of Daphnia that respond to elemental food quality. Ultimately, these effects of nutrition on host-parasite interactions would potentially influence the spread of infectious diseases and their role in ecosystems.