Nest-dwelling ectoparasites reduce antioxidant defences in females and nestlings of a passerine: a field experiment

Abstract

Ectoparasites may imply a cost in terms of oxidative stress provoked by inflammatory responses in hosts. Ectoparasites may also result in costs for nestlings and brooding females because of the direct loss of nutrients and reduced metabolic capacity resulting from parasite feeding activities. These responses may involve the production of reactive oxygen and nitrogen species that may induce oxidative damage in host tissues. Our goal was to examine the effect of ectoparasites in terms of oxidative stress for nestlings and adult females in a population of pied flycatchers Ficedula hypoleuca. We manipulated the entire nest ectoparasite community by reducing ectoparasite loads in some nests through a heating treatment and compared them with a control group of nests with natural loads. A marker of total antioxidant capacity (TAS) in plasma and total levels of glutathione (tGSH) in red blood cells as well as a marker of oxidative damage in plasma lipids (malondialdehyde; MDA) were assessed simultaneously. Levels of tGSH were higher in heat-treated nests than in controls for both females and nestlings. Higher TAS values were observed in females from heat-treated nests. In nestlings there was a negative correlation between TAS and MDA. Our study supports the hypothesis that ectoparasites expose cavity-nesting birds to an oxidative challenge. This could be paid for in the long term, ultimately compromising individual fitness.

Context‐dependent effects of yolk androgens on nestling growth and immune function in a multibrooded passerine

“…The fact that proliferation was higher in first clutches (but see Merino et al ., ), when breeding conditions were the most suitable (reviewed in Lindén & Møller, ; Styrsky et al ., ; Serra et al ., ; Salaberria et al ., ), is in agreement with this context‐dependent effect of androgens (Verboven et al ., ; Sockman et al ., ), which could be beneficial when plenty nutritional resources were available, but detrimental when food was scarce (reviewed in Smiseth et al ., ). Not only differences in overall food quantity and quality across the breeding season, but also the differential exposure to parasites and pathogens of first and second broods (López‐Rull et al ., ) could explain the contrasted effects on cell‐mediated immunity detected (de Lope et al ., ; Biard et al ., ; López‐Arrabé et al ., ). Finally, this context‐dependent effect of androgens on immunity would also help to explain the controversial results obtained when addressing the immunocompetence handicap hypothesis (Owen‐Ashley et al ., ; Roberts et al ., ; Navara et al ., ; Alonso‐Alvarez et al ., ).…”

“…In this way, we monitored a variety of developmental and physiological parameters that may be affected by yolk androgens and that may allow us to track the variation in the trade-offs associated with androgen allocation to eggs across the breeding season. We hypothesized that a seasonal decline in yolk androgen allocation (L opez-Rull et al, 2010;Vergauwen et al, 2012) could be due to possible detrimental effects on the nestlings of the second brood. The outcome of the androgen-mediated trade-off between offspring development and immunocompetence is expected to depend on environmental circumstances such as food availability (reviewed in Royle et al, 2001;Sockman et al, 2006;Smiseth et al, 2011), ectoparasite load (Tschirren et al, 2004;but see M€ uller et al, 2007a,b;L opez-Rull et al, 2010) and perhaps climatic conditions during breeding (Wingfield, 2003).…”

Harsh conditions during early development influence telomere length in an altricial passerine: Links with oxidative stress and corticosteroids

“…TAS estimates the combined action of nonenzymatic antioxidants in a plasma sample, and it was measured following Cohen (2007), with minor modifications described in López‐Arrabé et al. (, ). Plasma samples (5 μl) were mixed with 15 μl metmyoglobin and 250 μl ABTS (2,2‐azino‐di‐[3‐ethylbenzthiazolinesulphonate]) metmyoglobin and 50 ml hydrogen peroxide.…”

Do parasites and antioxidant availability affect begging behaviour, growth rate and resistance to oxidative stress?

“…higher growth rates increase oxidative stress). Begging displays also presumably induce oxidative costs through an excessive release of reactive species (Hasselquist & Nilsson, ; Moreno‐Rueda et al ., ) or through reduced antioxidant defences (López‐Arrabé et al ., ). Begging displays have been shown to be constrained by oxidative stress in barn swallows (Boncoraglio et al ., ) and by antioxidant availability in yellow‐legged gulls (Noguera et al ., ).…”