Developmental, metabolic and immunological costs of flea infestation in the common vole

Abstract

Summary 1.Parasites use resources from their hosts, which can indirectly affect a number of host functions because of trade-offs in resource allocation. In order to get a comprehensive view of the costs imposed by blood sucking parasites to their hosts, it is important to monitor multiple components of the development and physiology of parasitized hosts over long time periods. 2. The effect of infestation by fleas on body mass, body length growth, haematocrit, resistance to oxidative stress, resting metabolic rate and humoral immune response were experimentally evaluated. During a 3-month period, male common voles, Microtus arvalis , were either parasitized by rat fleas ( Nosopsyllus fasciatus ), which are naturally occurring generalist ectoparasites of voles, or reared without fleas. Then voles were challenged twice by injecting Keyhole Limpet Haemocyanin (KLH) to assess whether the presence of fleas affects the ability of voles to produce antibodies against a novel antigen. During the immune challenge we measured the evolution of body mass, haematocrit, resistance to oxidative stress and antibody production. 3. Flea infestation negatively influenced the growth of voles. Moreover, parasitized voles had reduced haematocrit, higher resting metabolic rate and lower production of antibodies against the KLH. Resistance to oxidative stress was not influenced by the presence of fleas. 4. During the immune challenge with KLH, body mass decreased in both groups, while the resistance to oxidative stress remained stable. In contrast, the haematocrit decreased only in parasitized voles. 5. Our experiment shows that infestation by a haematophageous parasite negatively affects multiple traits like growth, energy consumption and immune response. Fleas may severely reduce the survival probability and reproductive success of their host in natural conditions.

Flea infestation reduces the life span of the common vole

“…Nevertheless, the immune effort by itself does not shorten the life span of common voles (Devevey et al 2009). Moreover, rodents parasitized by fleas are immuno-depressed (Devevey et al 2008 ;Goü y de Bellocq et al 2006), and this makes them more sensitive to diseases. Alternatively, the spleen may also act as an erythropoietic organ in microtines (Watkins et al 1991), and thus splenomegaly observed in this study could be due to a combined effect of immune activation and the necessity to produce new red blood cells.…”

Reduced ectoparasite loads of deer mice in burned forest: From fleas to trees?

“…v www.esajournals.org There is growing evidence that ectoparasites can have significant negative impacts on the physiology of individual hosts, and the vital rates of host populations (Hawlena et al 2006a, Hawlena et al 2006b, Devevey et al 2008, Devevey and Christe 2009, Pfäffle et al 2009, Kam et al 2010. Therefore, it is conceivable that lowered ectoparasite loads in burned forest contribute to high post-fire deer mouse abundance, e.g., through effects on body condition (Hawlena et al 2006a, Devevey et al 2008, Devevey and Christe 2009 or feeding behavior (Scantlebury et al 2007, Raveh et al 2011), which in turn influences reproductive output of deer mice. Intriguingly, Raveh et al (2011) showed that flea-infested rodents were less vigilant and v www.esajournals.org had higher giving-up densities (i.e., tended to quit foraging at higher densities of food remaining in the patch).…”

“…On the other hand, there are multiple studies demonstrating individual-level impacts of ectoparasites on hosts, with most research conducted on fleas. In laboratory studies, fleas were found to affect body condition, growth rate, life span, and energy expenditure of their hosts (e.g., Hawlena et al 2006a, Devevey et al 2008, Devevey and Christe 2009. In free-living animals, ectoparasites influenced host energy budgets (Giorgi et al 2001, Nilsson 2003, Kam et al 2010, litter size (Neuhaus 2003), foraging and vigilance patterns (Scantlebury et al 2007, Raveh et al 2011, and juvenile survival (Hawlena et al 2006b).…”

Does investment into “expensive” tissue compromise anti-parasitic defence? Testes size, brain size and parasite diversity in rodent hosts

“…A host defends itself against parasites using behavioural and/or immunological tools both of which incur substantial energetic (Sheldon and Verhulst 1996;Giorgi et al 2001;Schmid-Hempel and Ebert 2003;Devevey et al 2008) and subsequent fitness costs (Hanssen et al 2004). This may be especially true when a host is subjected to multiple parasite challenges (Taylor et al 1998).…”