Ceratophyllus Gallinae Research Articles

Experimental manipulation of nest temperature and relative humidity reduces ectoparasites and affects body condition of Blue Tits (Cyanistes caeruleus)

Many models predict changes in the distribution and incidence of diseases associated with climate change. However, studies exploring the effect of microclimatic changes on host–parasite relationships are scarce. In this study, we increased temperature or humidity in Eurasian Blue Tit Cyanistes caeruleus nestboxes during the breeding season, to analyse the effect of each variable on the abundance of ectoparasites and, also, on the body condition of the hosts. Temperature and humidity were experimentally increased on average by about 2°C and 15%, respectively. The abundance of blowfly Protocalliphora azurea pupae was significantly reduced in nests with increased temperature compared with control nests and those with increased humidity, and was also significantly reduced in nests with increased humidity compared with control nests. The abundance of mites Dermanyssus spp. was significantly reduced in nests with increased humidity. However, there was no significant effect of the experiment on the abundance of flea Ceratophyllus gallinae larvae, biting midges (Culicoides spp.) and blackflies (Simuliidae). The body condition of nestlings was lower in nests with increased humidity and slightly lower in heated nests. However, the body condition of adults was not significantly affected by the experiment. In addition, blowfly pupae and biting midge abundance were negatively related to the body condition of the nestlings, and biting midge abundance was also negatively related to the body condition of the adults. Overall, an increase in temperature and humidity reduces the abundance of ectoparasites, which suggests that these parasites are sensitive to sudden changes in the microclimate in which they develop. Moreover, these fluctuations negatively affect the body condition of Blue Tit nestlings despite the concurrent decrease of parasites in nests. In other words, the expected benefit to the nestlings from the reduction in parasites does not occur because the microclimate also adversely affects nestlings, probably affecting their heat exchange with the nest environment.

Fleas (Siphonaptera) of small mammals in the northern taiga of Western Siberia

The purpose of the research is to identify the composition of fleas, and infection rates in small mammals in the northern taiga of Western Siberia; and to summarize information on fleas in the studied area. Materials and methods. In 2008, 2010, and 2016–2021, records of small mammals and their ectoparasites (fleas) were made in the northern taiga of Western Siberia. Parasitological survey was performed for 1363 specimens of insectivores and rodents of 13 species that were recorded using trap trenches, drift fences and trap-lines. A total of 1524 fleas of 18 species were recorded. Indices widely accepted in parasitology were used to assess quantitative indicators of fleas. Results and discussion. Based on the results of our own research and literature sources, small mammals in the northern taiga of Western Siberia were found to have specimens of 28 flea species. The flea fauna of the study area was represented by shrew fleas (Corrodopsylla birulai, Palaeopsylla sorecis), bird fleas (Ceratophyllus gallinae, C. garei), and specific species (Ceratophyllus anisus, C. indages, C. sciurorum, Megabothris walkeri, Leptopsylla segnis). Peromyscopsylla silvatica, Corrodopsylla birulai, Megabothris rectangulatus, Amalaraeus penicilliger, and Amphipsylla sibirica comprise the backbone of the flea fauna of small mammals in the northern taiga of Western Siberia.

Influence of nest box design and nesting material on ectoparasite load for four woodland passerines

ABSTRACT Capsule Abundance of haematophagous ectoparasites in woodland passerine nests is influenced by complex interactions between nest box design, bird species, amount of nesting material and nest composition. Aims To analyse ectoparasite abundance relative to nest box design (old wooden nest boxes present for over 2 years versus new wooden nest boxes of the same dimensions vs deep wooden nest boxes designed to reduce predation risk) and bird species (Blue Tit Cyanistes caeruleus, Great Tit Parus major, Pied Flycatcher Ficedula hypoleuca and Eurasian Nuthatch Sitta europaea). The potential influence of amount of nesting material and nest composition was also studied. Methods After fledging, nests were collected from nest boxes. Ectoparasites and nest materials were identified and quantified. Generalized linear modelling was used to examine the influence of nest box design, bird species, amount of nest material and nest composition on ectoparasite loads. Akaike’s Information Criterion was used to select optimal models. Results Abundance of Hen Fleas Ceratophyllus gallinae and parasitic Blowfly Protocalliphora was significantly higher for deep nest boxes than nest boxes of standard dimensions. Old nest boxes had significantly higher loads than new nest boxes, despite thorough cleaning between breeding seasons. Hen Flea abundance was highest in Eurasian Nuthatch nests. Blowfly abundance was highest in Pied Flycatcher nests. Abundances of both fleas and blowfly were positively related to nest mass and amount of animal hair in the nest, and, for parasitic Blowfly, were negatively related to the amount of tree bark. Conclusion Ectoparasite load depends not only on bird species but also nest box design and nesting material. We recommend: (1) nest boxes are regularly replaced to reduce parasite load; (2) deep nest boxes are not used as the large nests constructed not only remove anti-predator benefits of eggs/chicks being harder to reach but are also associated with high haematophagous ectoparasite loads.

Within-brood body size and immunological differences in Blue Tit (Cyanistes caeruleus) nestlings relative to ectoparasitism

Several ectoparasites parasitise nestlings decreasing their body condition, growth and survival. To minimise any loss of fitness due to ectoparasites, birds have developed a wide variety of defence mechanisms, potentially including hatching asynchrony. According to the Tasty Chick Hypothesis (TCH), the cost of parasitism would be reduced if ectoparasites tend to eat on less immunocompetent nestlings, typically the last-hatched chick in asynchronously hatched broods, as they are in poor body condition. Two predictions of the TCH are that immune capacity is lower in smaller nestlings than in larger ones and that parasites should provoke a more negative effect on smaller nestlings. Here, we test these predictions in a population of Blue Tits (Cyanistes caeruleus) whose broods are parasitised by Hen Fleas (Ceratophyllus gallinae) and Blowflies (Protocalliphora azurea). We recorded the presence of both ectoparasites and analysed the immunocompetence (number of leucocytes per 10,000 erythrocytes and cutaneous immune response to phytohaemagglutinin) and body condition of smaller and larger nestlings within individual broods. The leucocyte count was higher in smaller nestlings than in larger ones, whereas the cutaneous immune response did not differ between smaller and larger nestlings. Smaller nestlings, but not larger nestlings, had lower body mass when fleas were present. Blowflies, by contrast, had no detectable negative effect on nestlings. Overall, our findings provide partial support to the TCH. Lower immune capacity in smaller nestlings than in larger ones was not supported, but Hen Fleas seemed to negatively impact on smaller nestlings more than on larger ones.

Blue tit Cyanistes caeruleus males increase their reproductive effort when subject to a flea experimental manipulation

Parasites exert a strong selection pressure on their hosts as manifested in behavioural antiparasite traits to reduce negative impacts on fitness. The numerous nest‐dwelling ecto‐parasites residing in avian nests make altricial birds excellent model‐systems for investigating the relationship between parasites and their hosts. Here, we experimentally increased natural levels of hen fleas Ceratophyllus gallinae in blue tit Cyanistes caeruleus nests during incubation, and tested their effects on parental incubation behaviours and reproductive performance. Our experimental addition of fleas resulted in an increase in feeding effort of males to incubating females. Frequency of male feedings was also positively related to clutch size. These results suggest that males increase their reproductive effort in flea manipulated and large broods. This will, at least partly, compensate female costs in nests with high ecto‐parasite density and many nestlings. Furthermore, nestling mass at day six in experimental nests decreased with brood size, which was not the case in nests with a natural level of fleas. In line with male incubation feeding, parents may try to compensate for the costs inflicted by the fleas but can only partly compensate when brood size is large.

Sex-specific effects of experimental ectoparasite infestation on telomere length in great tit nestlings.

Telomere length is a biomarker of biological ageing and lifespan in various vertebrate taxa. Evidence is accumulating that telomeres shorten more rapidly when an individual is exposed to environmental stressors. Parasites are potent selective agents that can cause physiological stress directly or indirectly through the activation of the host's immune system. Yet to date, empirical evidence for a role of parasites in telomere dynamics in natural populations is limited. Here, we show experimentally that exposure to ectoparasitic hen fleas (Ceratophyllus gallinae) during growth results in shorter telomeres in female, but not male, great tit (Parus major) nestlings. Females had longer telomeres than males when growing up in experimentally deparasitized nests but, likely because of the sex-specific effects of ectoparasitism on telomere length, this sexual dimorphism was absent in birds growing up in experimentally infested nests. Our results provide the first experimental evidence for a role of ectoparasitism in telomere dynamics in a natural vertebrate population, and suggest that the costs of infection manifest in sex-specific ways.

Bacterial microbiota composition of a common ectoparasite of cavity‐breeding birds, the Hen Flea Ceratophyllus gallinae

Experimental field studies have demonstrated negative fitness consequences of Hen Flea Ceratophyllus gallinae infestations for bird hosts, yet it is currently unclear whether these negative effects are a direct consequence of flea‐induced blood loss or a result of flea‐borne pathogen transmission. Here we used a 16S rRNA gene sequencing approach to characterize the bacterial microbiota community of Hen Fleas collected from Great Tit Parus major nests and found that Brevibacterium (Actinobacteria), Staphylococcus (Firmicutes), Stenotrophomonas (Proteobacteria), Massilia (Proteobacteria), as well as the arthropod endosymbionts ‘Candidatus Lariskella’ and ‘Candidatus Midichloria’ were most abundant. We found evidence for the occurrence of Staphylococcus spp. in Hen Fleas, which may cause opportunistic infections in bird hosts, but not of other known pathogens commonly transmitted by other flea species, such as Bartonella spp. or Rickettsia spp. However, Hen Fleas might transmit other pathogens (e.g. viruses or bacteria that are not currently recognized as bird pathogens), which may contribute to the negative fitness consequences of Hen Flea infestations in addition to direct blood loss or secondary infections of wounds caused by biting fleas.

Insect ectoparasites from wild passerine birds in the Azores Islands.

A total of 266 wild passerine birds (Passeriformes) representing eight species and nine subspecies from three islands of the Archipelago of the Azores were examined for ectoparasites. Two species of louse-flies Ornithomya avicularia and Ornithoica turdi (Diptera: Hippoboscidae), three species of fleas Ceratophyllus gallinae, Ceratophyllus sp. and Dasypsyllus gallinulae (Siphonaptera: Ceratophyllidae), and 11 species of chewing lice belonging to the genera Menacanthus, Myrsidea (Phthiraptera: Menoponidae), Ricinus (Phthiraptera: Ricinidae), Brueelia, Guimaraesiella, Philopterus, Sturnidoecus and Turdinirmus (Phthiraptera: Philopteridae) were recorded. At least one species of ectoparasite was found on 114 birds of six species. Guimaraesiella tovornikae and Myrsidea sylviae from Sylvia atricapilla are redescribed. Records of Ceratophyllus sp. and Sturnidoecus sp. from Turdus merula represent new parasite-host associations. Phoresy of Guimaraesiella amsel on Ornithoica turdi was also found. Parasitological parameters such as prevalence, intensity and abundance and geographic distribution of recorded ectoparasites are provided.

Gene flow and adaptive potential in a generalist ectoparasite

BackgroundIn host-parasite systems, relative dispersal rates condition genetic novelty within populations and thus their adaptive potential. Knowledge of host and parasite dispersal rates can therefore help us to understand current interaction patterns in wild populations and why these patterns shift over time and space. For generalist parasites however, estimates of dispersal rates depend on both host range and the considered spatial scale. Here, we assess the relative contribution of these factors by studying the population genetic structure of a common avian ectoparasite, the hen flea Ceratophyllus gallinae, exploiting two hosts that are sympatric in our study population, the great tit Parus major and the collared flycatcher Ficedula albicollis. Previous experimental studies have indicated that the hen flea is both locally maladapted to great tit populations and composed of subpopulations specialized on the two host species, suggesting limited parasite dispersal in space and among hosts, and a potential interaction between these two structuring factors.ResultsC. gallinae fleas were sampled from old nests of the two passerine species in three replicate wood patches and were genotyped at microsatellite markers to assess population genetic structure at different scales (among individuals within a nest, among nests and between host species within a patch and among patches). As expected, significant structure was found at all spatial scales and between host species, supporting the hypothesis of limited dispersal in this parasite. Clustering analyses and estimates of relatedness further suggested that inbreeding regularly occurs within nests. Patterns of isolation by distance within wood patches indicated that flea dispersal likely occurs in a stepwise manner among neighboring nests. From these data, we estimated that gene flow in the hen flea is approximately half that previously described for its great tit hosts.ConclusionOur results fall in line with predictions based on observed patterns of adaptation in this host-parasite system, suggesting that parasite dispersal is limited and impacts its adaptive potential with respect to its hosts. More generally, this study sheds light on the complex interaction between parasite gene flow, local adaptation and host specialization within a single host-parasite system.

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

Early-life trade-offs faced by developing offspring can have long-term consequences for their future fitness. Young offspring use begging displays to solicit resources from their parents and have been selected to grow fast to maximize survival. However, growth and begging behaviour are generally traded off against self-maintenance. Oxidative stress, a physiological mediator of life-history trade-offs, may play a major role in this trade-off by constraining, or being costly to, growth and begging behaviour. Yet, despite implications for the evolution of life-history strategies and parent-offspring conflicts, the interplay between growth, begging behaviour and resistance to oxidative stress remains to be investigated. We experimentally challenged wild great tit (Parus major) offspring by infesting nests with a common ectoparasite, the hen flea (Ceratophyllus gallinae), and simultaneously tested for compensating effects of increased vitamin E availability, a common dietary antioxidant. We further quantified the experimental treatment effects on offspring growth, begging intensity and oxidative stress. Flea-infested nestlings of both sexes showed reduced body mass during the first half of the nestling phase, but this effect vanished short before fledging. Begging intensity and oxidative stress of both sexes were unaffected by both experimental treatments. Feeding rates were not affected by the experimental treatments, but parents of flea-infested nests fed nestlings with a higher proportion of caterpillars, the main source of antioxidants. Additionally, female nestlings begged significantly less than males in control nests, whereas both sexes begged at similar rates in vitamin E-supplemented nests. Our study shows that a parasite exposure does not necessarily affect oxidative stress levels or begging intensity, but suggests that parents can compensate for negative effects of parasitism by modifying food composition. Furthermore, our results indicate that the begging capacity of the less competitive sex is constrained by antioxidant availability.

Relative fitness of a generalist parasite on two alternative hosts: a cross‐infestation experiment to test host specialization of the hen flea Ceratophyllus gallinae (Schrank)

Host range is a key element of a parasite's ecology and evolution and can vary greatly depending on spatial scale. Generalist parasites frequently show local population structure in relation to alternative sympatric hosts (i.e. host races) and may thus be specialists at local scales. Here, we investigated local population specialization of a common avian nest-based parasite, the hen flea Ceratophyllus gallinae (Schrank), exploiting two abundant host species that share the same breeding sites, the great tit Parus major (Linnaeus) and the collared flycatcher Ficedula albicollis (Temminck). We performed a cross-infestation experiment of fleas between the two host species in two distinct study areas during a single breeding season and recorded the reproductive success of both hosts and parasites. In the following year, hosts were monitored again to assess the long-term impact of cross-infestation. Our results partly support the local specialization hypothesis: in great tit nests, tit fleas caused higher damage to their hosts than flycatcher fleas, and in collared flycatcher nests, flycatcher fleas had a faster larval development rates than tit fleas. However, these results were significant in only one of the two studied areas, suggesting that the location and history of the host population can modulate the specialization process. Caution is therefore called for when interpreting single location studies. More generally, our results emphasize the need to explicitly account for host diversity in order to understand the population ecology and evolutionary trajectory of generalist parasites.

On the fleas and louse (Insecta: Siphonaptera and Anoplura) of the garden dormouse, Eliomys quercinus (L. 1766) in Belgium

SummaryMore than 3500 fleas, collected in southern Belgium, from 54 garden dormice (Eliomys quercinus) and from 58 nests of the rodent, were examined. Ceratophyllus s. sciurorum seems to be the only regular and abundant flea on the garden dormouse and in its nest whereas Myoxopsylla laverani is quite uncommon (5/31 infested animal and 11/52 infested nests). In comparison, 96 garden dormice were checked in France. M. laverani is present on nearly every infested animal (61/66). Other fleas were also found, some mammal-fleas (Megabothris turbidus, Hystrichopsylla talpae, several Ctenophthalmus spp.) and great numbers of bird-fleas (Ceratophyllus gallinae and Dasypsyllus gallinulae) because the dormouse-nests where the fleas were taken were built on old tit-nests (Parus spp). Finally, Schizophthirus pleurophaeus, a louse, was collected for the first time in Belgium.

Pied Flycatchers Ficedula hypoleuca prefer ectoparasite-free nest sites when old nest material is present

Nest-dwelling ectoparasitic arthropods may have detrimental effects on avian breeding success and fitness. Birds should therefore be selected to avoid nest sites where the risk of being infested by ectoparasites is high. However, studies testing this hypothesis have produced mixed results. We performed an experiment in south Norway to test whether Pied Flycatchers Ficedula hypoleuca select nest site according to the presence of ectoparasites. We used artificial nest boxes in this experiment which had all been successfully used by conspecifics in the previous breeding season and still contained the old nest material. Five different groups of ectoparasites were recorded in flycatcher nests in the study area, of which the haematophagous hen flea Ceratophyllus gallinae and mites (Dermanyssus sp.) occurred in all examined nests. We offered each flycatcher pair (n = 13) a choice between 1) a box where ectoparasites had been removed by insecticide fumigation and 2) a box in which the old nest had not been fumigated. Flycatchers were highly selective in their choice of nest site, all but one settling in the fumigated, parasite-free nest box. This finding differs from a similar Swedish study (Olsson & Allander 1995) which did not find any evidence that Pied Flycatchers avoided nest boxes with ectoparasites. A likely explanation for this discrepancy is between-population differences in parasite abundance, as the mean number of hen fleas per infested nest was about five times higher in Norway than in Sweden.

Integrated morphological and molecular identification of cat fleas (Ctenocephalides felis) and dog fleas (Ctenocephalides canis) vectoring Rickettsia felis in central Europe

Fleas of the genus Ctenocephalides are the most common ectoparasites infesting dogs and cats world-wide. The species Ctenocephalides felis and Ctenocephalides canis are competent vectors for zoonotic pathogens such as Rickettsia felis and Bartonella spp. Improved knowledge on the diversity and phylogenetics of fleas is important for understanding flea-borne pathogen transmission cycles. Fleas infesting privately owned dogs and cats from the Czech Republic (n=97) and Romania (n=66) were subjected to morphological and molecular identification and phylogenetic analysis. There were a total of 59 (60.82%) cat fleas (Ctenocephalides felis felis), 30 (30.93%) dog fleas (Ctenocephalides canis), 7 (7.22%) European chicken fleas (Ceratophyllus gallinae) and 1 (1.03%) northern rat flea (Nosopsyllus fasciatus) collected in the Czech Republic. Both C. canis and C. felis felis were identified in Romania. Mitochondrial DNA sequencing at the cox1 gene on a cohort of 40 fleas revealed the cosmopolitan C. felis felis clade represented by cox1 haplotype 1 is present in the Czech Republic. A new C. felis felis clade from both the Czech Republic and Romania is also reported. A high proportion of C. canis was observed from dogs and cats in the current study and phylogeny revealed that C. canis forms a sister clade to the oriental cat flea Ctenocephalides orientis (syn. C. felis orientis). Out of 33 fleas tested, representing C. felis felis, C. canis and Ce. gallinae, 7 (21.2%) were positive for R. felis using diagnostic real-time PCR targeting the gltA gene and a conventional PCR targeting the ompB gene. No samples tested positive for Bartonella spp. using a diagnostic real-time PCR assay targeting ssrA gene. This study confirms high genetic diversity of C. felis felis globally and serves as a foundation to understand the implication for zoonotic disease carriage and transmission by the flea genus Ctenocephalides.

Parasites suppress immune-enhancing effect of methionine in nestling great tits.

After birth, an organism needs to invest both in somatic growth and in the development of efficient immune functions to counter the effects of pathogens, and hence an investment trade-off is predicted. To explore this trade-off, we simultaneously exposed nestling great tits (Parus major) to a common ectoparasite, while stimulating immune function. Using a 2 × 2 experimental design, we first infested half of the nests with hen fleas (Ceratophyllus gallinae) on day 3 post-hatch and later, on day 9-13 post-hatch, and then supplemented half of the nestlings within each nest with an immuno-enhancing amino acid (methionine). We then assessed the non-specific immune response by measuring both the inflammatory response to a lipopolysaccharide (LPS) and assessing the levels of acute phase proteins (APP). In parasite-infested nestlings, methionine had a negative effect on body mass close to fledging. Methionine had an immune-enhancing effect in the absence of ectoparasites only. The inflammatory response to LPS was significantly lower in nestlings infested with fleas and was also lower in nestlings supplemented with methionine. These patterns of immune responses suggest an immunosuppressive effect of ectoparasites that could neutralise the immune-enhancing effect of methionine. Our study thus suggests that the trade-off between investment in life history traits and immune function is only partly dependent on available resources, but shows that parasites may influence this trade-off in a more complex way, by also inhibiting important physiological functions.

Parasite- and predator-induced maternal effects in the great tit ( Parus major )

Both predators and parasites can elicit behavioral and physiological responses in prey and hosts, respectively. These responses may involve the reallocation of resources and may thus limit each other. We investigated the effects of concurrent pre-laying exposure of great tit females ( Parus major ) to both a simulated predation risk and a nest-based ectoparasite, the hen flea ( Ceratophyllus gallinae ), on nestling growth and development. We manipulated perceived predation risk using models and vocalizations of sparrowhawks ( Accipiter nisus ). At the start of incubation, we swapped whole clutches between treated and untreated nests to separate pre-laying maternal effects from posthatching effects. Since costs and benefits of maternal responses to parasites need to be assessed under parasite pressure, we infested half of the rearing nests with hen fleas. Parasites had negative effects on mass gain and wing growth, both via maternal effects and via direct exposure of nestlings, whereas maternal predation risk had no significant effect. The interaction between predator and parasite treatments was not significant and, thus, suggests the absence of a trade-off between the 2 stressors operating at the level of maternal effects. Alternatively, the complexity of the design, despite a relatively large sample size, may have limited the power for detection of this expected trade-off.

Fleas in nests of the White-throated Dipper Cinclus cinclus in Norway

We collected nest material from six White-throated Dipper Cinclus cinclus nests in 2006 and from 14 nests in 2007. Eight nests were located in Hedmark, one in Akershus and 11 in Vest-Agder. In addition, we also include results from material sampled in 1922 (one nest from Nordland), 1969 (three nests from Akershus) and 1971 (one nest from More og Romsdal). In the material, we recorded three species of bird fleas. The hen flea Ceratophyllus gallinae and the moorhen flea Dasypsyllus gallinulae were the most common ones; in addition, we found Ceratophyllus garei in one nest. In the material from one nest, we found an extremely high number of D. gallinulae , 3740 specimens dispersed out of the nest material.

Arthropods (Acarina, Coleoptera, Siphonaptera) in nests of hoopoe (Upupa epops) in Central Europe

AbstractIn 1993–1995 and 2009–2011, during investigation of reproduction biology of hoopoe, 63 nests of this species were collected after fledging of the chicks in Slovakia and Austria and their arthropod fauna was analyzed. Altogether 5,481 individuals and 34 species of mesostigmatic mites were found in 82.5% of the nests examined. The nidicolous mite Androlaelaps casalis was most abundant and frequent, representing 91.7% of all individuals. The richest in species were saprophilous mites (64.7% of all recorded species), while ectoparasites of the genera Dermanyssus and Ornithonyssus represented only 0.4% of all mites. Only 8 beetle species represented by 65 individuals were found in 18 nests. The dominant trophical group were carnivores (mainly nidicolous Gnathoncus buyssoni) with almost identical representation in (86.2%), followed by a similar representation of necrophags (10.8%). Unlike nests of other birds, the typical nidicolous species Haploglossa puncticollis and the fungivors were absent due to the dry character of studied countryside and placement of the nests in boxes situated in vineyard cottages. Only one species of fleas, Ceratophyllus gallinae — parasitizing first of all in the passeriform birds and being particularly abundant in the cavity nesting birds was recorded in hoopoe nests.

Ectoparasite reproductive performance when host condition varies

Host condition can influence both the nutritive resources available to parasites and the strength of host defences. Since these factors are likely to be correlated, it is unclear whether parasites would be more successful on hosts in good, intermediate or poor conditions. For more complex parasites, like fleas, where larvae depend on adults to extract and make available some essential host resources, host condition can act at two levels. First, it can affect the investment of females into eggs, and second, it can influence offspring growth. In a two-step experiment, we first let female hen fleas Ceratophyllus gallinae feed on nestlings of reduced, control or enlarged great tit Parus major broods and secondly used the blood from these nestlings as a food source for flea larvae reared in the laboratory. We then assessed the effect of brood size manipulation on reproductive investment and survival of female fleas, and on survival, developmental time, mass and size of pre-imago larvae and adults of the first generation. Although host condition, measured as body mass controlled for body size, was significantly influenced by brood size manipulation, it did not affect the female fleas' reproductive investment and survival. Larvae fed with blood from nestlings of reduced broods lived longer, however, than larvae fed on blood from enlarged or control broods. Additionally, F1 adults grew shorter tibiae when their mother had fed on hosts of reduced broods. The finding that brood size manipulation influenced parasite reproduction suggests that it affected nutritive resources and/or host defence, but the precise mechanism or balance between the two requires further investigation.

Intraclutch variation in avian eggshell pigmentation: the anaemia hypothesis

Many passerine species lay eggs that are speckled with dark protoporphyrin pigmentation. Because protoporphyrin is mainly derived from the blood, we here formulate and test a new hypothesis that links an increase in anaemia along the laying sequence to within-clutch variation in egg pigmentation. More intense pigmentation is expected if pigments accumulate during enhanced red blood cell production in response to anaemia. Reduced pigmentation is expected if pigments are derived from the degradation of red blood cells that circulate in smaller numbers due to blood loss. To test this hypothesis, we manipulated anaemia in great tit (Parus major) females by infesting the nests with hen fleas (Ceratophyllus gallinae) prior to egg laying. Polychromatophil (i.e., immature red blood cells) percentage, as a measure of blood cell production, was positively correlated with parasite load confirming that female great tits experienced stronger anaemia when infested with haematophagous parasites during egg laying. We found a positive relationship between spot darkness and laying order that weakened under high parasite load. This result suggests that anaemia in females due to blood-sucking parasites led to diminished protoporphyrin from disintegrated red blood cells and hence a decreased deposition of protoporphyrin. However, the overall increase in pigment darkness along the laying sequence suggests that pigments also accumulate by enhanced red blood cell production caused by anaemia due to egg production itself.