Energetic costs of parasitism in the Cape ground squirrel Xerus inauris

    Authors

    M. Scantlebury; J. M. Waterman; M. Hillegass; J. R. Speakman;N. C. Bennett

    Comments

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    Abbreviated Journal Title

    Proc. R. Soc. B-Biol. Sci.

    Keywords

    energy; parasite; ground squirrel; resting metabolic rate; doubly; labelled water; life history; DOUBLY-LABELED WATER; BASAL METABOLIC-RATE; MITE SPINTURNIX-MYOTI; LABORATORY MICE; MUS MUSCULUS; BODY-WATER; NIPPOSTRONGYLUS-BRASILIENSIS; OXYGEN-CONSUMPTION; IMMUNE FUNCTION; CO2 PRODUCTION; Biology; Ecology; Evolutionary Biology

    Abstract

    Parasites have been suggested to influence many aspects of host behaviour. Some of these effects may be mediated via their impact on host energy budgets. This impact may include effects on both energy intake and absorption as well as components of expenditure, including resting metabolic rate (RMR) and activity (e.g. grooming). Despite their potential importance, the energy costs of parasitism have seldom been directly quantified in a field setting. Here we pharmacologically treated female Cape ground squirrels (Xerus inauris) with anti-parasite drugs and measured the change in body composition, the daily energy expenditure (DEE) using doubly labelled water, the RMR by respirometry and the proportions of time spent looking for food, feeding, moving and grooming. Post-treatment animals gained an average 19 g of fat or approximately 25 kJ d(-1). DEE averaged 382 kJ d-1 prior to and 375 kJ d-1 post treatment (p > 0.05). RMR averaged 174 kJ d-1 prior to and 217 kJ d-1 post treatment (p < 0.009). Post-treatment animals spent less time looking for food and grooming, but more time on feeding. A primary impact of infection by parasites could be suppression of feeding behaviour and, hence, total available energy resources. The significant elevation of RMR after treatment was unexpected. One explanation might be that parasites produce metabolic by-products that suppress RMR. Overall, these findings suggest that impacts of parasites on host energy budgets are complex and are not easily explained by simple effects such as stimulation of a costly immune response. There is currently no broadly generalizable framework available for predicting the energetic consequences of parasitic infection.

    Journal Title

    Proceedings of the Royal Society B-Biological Sciences

    Volume

    274

    Issue/Number

    1622

    Publication Date

    1-1-2007

    Document Type

    Article

    Language

    English

    First Page

    2169

    Last Page

    2177

    WOS Identifier

    WOS:000248809600014

    ISSN

    0962-8452

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