Flea Parasitism Research Articles

Fleas (Siphonaptera) in the Nests of Dormice (Gliridae: Rodentia) in Lithuania

Negative effects of flea (Siphonaptera) parasitism on the host may be expressed in different ways. The aim of this study was to assess distribution of the flea fauna in nests of dormice in Lithuania. Nests of Glis glis (L.), Dryomys nitedula (Pallas), and Muscardinus avellanarius (L.) were collected from nest boxes in 2012 and 2013. Fleas were collected from nests in the laboratory and put into plastic tubes with 70% ethanol. Flea species were identified using morphological keys. From 400 nest boxes, 112 nests of dormice were collected from eight sites from mixed forests of central Lithuania. Twenty-three nests of G. glis were collected from nest boxes, with 16 of them containing 286 fleas belonging to four species: Ceratophyllus sciurorum (Schrank) (259), C. gallinae (Schrank) (23), Hystrichopsylla talpae (Curtis) (3), and Megabothris turbidus (Rothschild) (1). Fourteen nests of M. avellanarius were collected from nest boxes, 4 of which contained 224 fleas belonging to two species: C. sciurorum (221) and C. gallinae (3). Twenty-four nests of D. nitedula were collected from nest boxes, including 17 containing 207 fleas belonging to two species: C. sciurorum (205) and C. gallinae (2). Fifty-one nests of undetermined dormice species also were collected from nest boxes, 12 of them contained 395 fleas belonging to three species: C. sciurorum (374), Ctenophthalmus agyrtes (Heller) (19), and Ctenophthalmus assimilis (Taschenberg) (2). C. sciurorum was a predominant species in the nests of dormice. The occurrence of C. gallinae was documented in Lithuania for the first time.

Drivers of Intensity and Prevalence of Flea Parasitism on Small Mammals in East African Savanna Ecosystems.

The relative importance of environmental factors and host factors in explaining variation in prevalence and intensity of flea parasitism in small mammal communities is poorly established. We examined these relationships in an East African savanna landscape, considering multiple host levels: across individuals within a local population, across populations within species, and across species within a landscape. We sampled fleas from 2,672 small mammals of 27 species. This included a total of 8,283 fleas, with 5 genera and 12 species identified. Across individual hosts within a site, both rodent body mass and season affected total intensity of flea infestation, although the explanatory power of these factors was generally modest (<10%). Across host populations in the landscape, we found consistently positive effects of host density and negative effects of vegetation cover on the intensity of flea infestation. Other factors explored (host diversity, annual rainfall, anthropogenic disturbance, and soil properties) tended to have lower and less consistent explanatory power. Across host species in the landscape, we found that host body mass was strongly positively correlated with both prevalence and intensity of flea parasitism, while average robustness of a host species to disturbance was not correlated with flea parasitism. Cumulatively, these results provide insight into the intricate roles of both host and environmental factors in explaining complex patterns of flea parasitism across landscape mosaics.

Bartonella infection in rodents and their flea ectoparasites: an overview.

Epidemiological studies worldwide have reported a high prevalence and a great diversity of Bartonella species, both in rodents and their flea parasites. The interaction among Bartonella, wild rodents, and fleas reflects a high degree of adaptation among these organisms. Vertical and horizontal efficient Bartonella transmission pathways within flea communities and from fleas to rodents have been documented in competence studies, suggesting that fleas are key players in the transmission of Bartonella to rodents. Exploration of the ecological traits of rodents and their fleas may shed light on the mechanisms used by bartonellae to become established in these organisms. The present review explores the interrelations within the Bartonella-rodent-flea system. The role of the latter two components is emphasized.

Rodents as hosts of infectious diseases: biological and ecological characteristics.

Rodents are recognized as hosts of more than 60 zoonotic diseases that represent a serious threat to human health (Meerburg et al. 2009, Luis et al. 2013). This special issue emerges from a workshop organized in Bangkok at the Faculty of Veterinary Medicine of Kasetsart University and supported by the French ANR project CERoPath (Community Ecology of Rodents and their Pathogens in a Southeast Asian changing environment), which aimed at better understanding the relationships between rodent-borne diseases, rodents and their habitats using intensive field works, serology, and molecular screenings. The main objective of this workshop was to join ecologists, biologists, and epidemiologists to give an overview on the importance of rodents as hosts and reservoirs of parasitic and infectious diseases. Most of presentations given in the workshop focused in Southeast Asia, a hotspot of both infectious emerging diseases (Coker et al. 2011) and biodiversity at threat due to dramatic changes in land use (Morand et al. 2014). A first challenge is related to the invasion or range expansion of rodents. The black rat (Rattus rattus), Norway rat (Rattus norvegicus), Asian house rat, (Rattus tanezumi) and Pacific rat (Rattus exulans) like the house mice (Mus musculus), have dramatically expanded their geographic range as a consequence of human activities (Aplin et al. 2011). All of these Rattus species originated in Asia, and can be found in sympatry due to their synanthropic behavior (McFarlane et al. 2012). These rodents have been implicated (Kosoy et al., this issue), and still are implicated (Kuo et al. 2011), in the emergence and spread of plague, murine typhus, scrub typhus, leptospirosis, hantavirus hemorrhagic fever, among others. A better comprehension of the range extension mechanisms and consequences in term of infectious diseases' risks would require investigation of the genetics and immunology of these rodent species (Himsworth et al., this issue) as well on the ecological interactions among pathogens, vectors, and rodents. Gutierrez et al. (this issue) in their review attempt to summarize and bridge some knowledge gaps in the transmission and distribution routes, and in the dynamics and composition of Bartonella-infection in rodents and their flea parasites. A second challenge is that in order to better understand disease ecology and parasite transmission, it must be considered that not all hosts are equally involved in parasite transmission as some species (and individuals) can be responsible for a disproportionate number of transmission events (Paull et al. 2012). Some habitats or landscapes may also disproportionally enhance transmission or persistence of parasite and/or vector (Bordes et al. 2013). Indeed, by carrying and disseminating parasites across multiple habitats, generalist or synanthropic rodents could enhance both host-switching and spill-over to other rodent reservoirs and directly or indirectly to humans. Several articles in this special issue suggest high diversity of pathogens and parasites circulating among diversified communities of rodents across various habitats, such as Rickettsia spp. in Taiwan (Kuo et al., this issue), Bartonella spp. in Vietnam (Hoang et al., this issue) and in Thailand (Jiyipong et al., in this issue), leptospirosis in Vietnam (Hoang et al., this issue), zoonotic viruses in Vietnam (Cuong et al., this issue), and zoonotic helminths in Thailand (Chaisiri et al., this issue). This special issue calls for a more thorough investigation of rodent-borne diseases taking into account the ecology of rodents in their habitats. Taken together, the studies presented in this special issue stress the need to identify the mechanisms affecting pathogen diversity and infection within and between rodent species and to explain why some rodent species seem to be more resilient to greater habitat disturbance. Future research should monitor a variety of rodent pathogens simultaneously, including directly-transmitted specific pathogens and vector-borne pathogens with varying degrees of specificity.

Variable effects of host characteristics on species richness of flea infracommunities in rodents from three continents

We studied the effect of host gender and body mass on species richness of flea infracommunities in nine rodent host species from three biomes (temperate zone of central Europe, desert of the Middle East and the tropics of East Africa). Using season- and species-specific generalized linear mixed models and controlling for year-to-year variation, spatial clustering of rodent sampling and over-dispersion of the data, we found inconsistent associations between host characteristics and flea species richness. We found strong support for male-biased flea parasitism, especially during the reproductive period (higher species richness in male hosts than in females) in all considered European rodents (Apodemus agrarius, Myodes glareolus and Microtus arvalis) and in one rodent species from the Middle East (Dipodillus dasyurus). In contrast, two of three African rodent species (Lophuromys kilonzoi and Praomys delectorum) demonstrated a trend of female-biased flea species richness. Positive associations between body mass and the number of flea species were detected mainly in males (five of nine species: A. agrarius, M. glareolus, M. arvalis, D. dasyurus and Mastomys natalensis) and not in females (except for M. natalensis). The results of this study support earlier reports that gender-biased, in general, and male-biased, in particular, infestation by ectoparasites is not a universal rule. This suggests that mechanisms of parasite acquisition by an individual host are species-specific and have evolved independently in different rodent host-flea systems.

Driven to distraction: detecting the hidden costs of flea parasitism through foraging behaviour in gerbils

Gerbilline rodents such as Allenby's gerbils (Gerbillus andersoni allenbyi), when parasitized by fleas such as Synosternus cleopatrae pyramidis, devote long hours of grooming to remove the ectoparasites. Yet no detrimental energetic or immunological effects of the ectoparasites have been found in adult Allenby's gerbil. Why should gerbils go to such trouble? We tested for the various ways that fleas can negatively affect gerbils by manipulating flea infestation on gerbils and the presence of a fox. We demonstrate that gerbils responded to fleas by leaving resource patches at higher giving-up densities. Furthermore, they stayed in those resource patches less time and left them at higher quitting harvest rates so long as a fox was also present. When flea-ridden, gerbils also abandoned using vigilance to manage risk and relied mainly on time allocation. Thus, having fleas imposed a foraging cost similar in nature to that arising from the risk of predation from foxes and may be even larger in magnitude. More than that, the presence of fleas acted as a magnifier of foraging costs, especially those arising from the risk of predation. The fleas reduced the gerbils' foraging aptitude and altered how they went about managing risk of predation. We hypothesize that fleas reduce the attention that gerbils otherwise have for foraging and predator detection. We suggest that this is the major cost of ectoparasitism.

Relative Importance of Demographics, Locale, and Seasonality Underlying Louse and Flea Parasitism of Raccoons (Procyon lotor)

A variety of demographic, seasonal, and site-specific variables may influence parasitism, but the relative importance of these variables is generally unclear. We measured the relative ability of host characteristics, season, and site to explain louse (Trichodectes octomaculatus) and flea (Orchopeas howardi) infestation across 10 populations of raccoons (Procyon lotor). Lice are highly dependent on specific hosts and are predicted to display a relatively strong relationship with factors intrinsic to the host, when compared to fleas, which can infest multiple species and survive off-host for weeks without feeding. We developed a priori models that represented explicit hypotheses and contrasted their ability to predict infestation patterns. While the abundance of lice was seasonal, models that included solely host age and sex best predicted prevalence and abundance, in part because males were infested with 3 times the number of lice than were females. Conversely, flea prevalence and abundance, which peaks sharply in the spring, was best predicted by season; factors intrinsic to the host were relatively unimportant for predicting abundance. These, and other, recent findings emphasize the need to simultaneously assess the relative importance of multiple ecological variables between parasite species when attempting to describe general trends and constraints of host-parasite associations.

Connectance and parasite diet breadth in flea‐mammal webs

The number of links in webs of species interactions, which lies at the heart of the biodiversity‐stability debate, has given rise to controversy during the last 20 yr. Studies exploring these web properties have mainly focused on symmetric webs where each species can potentially feed on any other species; asymmetric webs such as host‐parasite webs, where one set of species feed on another set of species, have been overlooked. However, food webs are incomplete without parasites and the study of parasite‐host sub‐web properties deserves attention. Here, using a large database involving 33 regional interaction webs between mammals and their flea parasites, we found a negative relationship between species richness and host‐parasite connectance. We suggest that some phylogenetic constraints on flea diet may explain our observed patterns because we found that parasite diet breadth, measured as host taxonomic diversity, was invariant along our host richness gradient. We found that the slope of the logarithmic relationship between the number of realized links and species richness is lower than slope values reported for food webs. We suggest that connectance may not respond to increasing species richness as rapidly in host‐parasite webs as in predator‐prey food webs due to stronger coevolutionary requirements.

Fleas parasitizing domestic dogs in Spain

In addition to their importance to veterinary clinical practice as ectoparasites, fleas of domestic dogs are of special concern because they can be vectors of disease, including zoonoses. Flea assemblages parasitizing domestic dogs usually comprise several flea species whose distribution is determined by factors acting at several scales. Knowledge of these factors will aid in assessment of the distribution patterns of flea parasitism, and is an important tool in developing control strategies and in evaluation of flea-borne disease risk in dogs and humans. In this survey we used data from 744 domestic dogs from 79 localities in Spain to explore the associations between the abundance of flea species, host-dependent factors (sex and age), and host habitat factors including abode (farm, house with garden, apartment), location (urban or rural), the presence of other pets, and dog activity (measured as the frequency with which dogs left their abode). We also considered environmental factors including the time of year and mean annual temperature and rainfall. Variations in flea community structure at infracommunity and component community levels were also explored. Four flea species were found parasitizing dogs. Ctenocephalides felis was the most abundant (88.02% of fleas identified), followed by Ctenocephalides canis (10.38%), Pulex irritans (1.47%) and Echidnophaga gallinacea (0.13%). Overall flea abundance was higher on dogs living on farms than in apartments, as was the abundance of Ct. felis, Ct. canis and P. irritans. Ct. felis was more abundant on dogs living in houses than in apartments, but the reverse was found for P. irritans. Overall flea abundance and Ct. canis abundance were highest in rural areas, whereas the presence of other pets sharing the abode was associated with higher overall flea abundance and Ct. felis abundance. Only P. irritans abundance was positively related to the activity of dogs. Ct. canis and P. irritans abundances were higher during the warm period of the year. Mean annual temperature was negatively correlated with overall, Ct. canis and P. irritans abundances, but positively related to Ct. felis abundance. Annual rainfall was negatively correlated with Ct. canis and P. irritans abundances. Variations in the number of flea species found on a dog reflected the abundance distribution patterns for each species and their associations with host habitat and environmental factors. At the component community level, flea species richness was inversely related to annual mean temperature. The structure of flea assemblages on dogs was mainly associated with host habitat and environmental variables, and not with host-dependent variables. However, a large amount of variation in flea abundance remained unexplained, suggesting the effect of other non-controlled factors.

Ultimate mechanisms of age-biased flea parasitism

Mechanisms that cause nonrandom patterns of parasite distribution among host individuals may influence the population and evolutionary dynamics of both parasites and hosts, but are still poorly understood. We studied whether survival, reproduction, and behavioral responses of fleas (Xenopsylla conformis) changed with the age of their rodent hosts (Meriones crassus), experimentally disentangling two possible mechanisms: (a) differential survival and/or fitness reward of parasites due to host age, and (b) active parasite choice of a host of a particular age. To explore the first mechanism, we raised fleas on rodents of two age groups and assessed flea survival as well as the quantity and quality of their offspring. To explore the second mechanism, three groups of fleas that differed in their previous feeding experience (no experience, experience on juvenile or experience on adult rodents) were given an opportunity to choose between juvenile and adult rodents in a Y-maze. Fleas raised on juvenile rodents had higher survival and had more offspring that emerged earlier than fleas raised on adults. However, fleas did not show any innate preference for juvenile rodents, nor were they able to learn to choose them. In contrast to our predictions, based on a single previous exposure, fleas learned to choose adult rodents. The results suggest that two mechanisms-differential survival and fitness reward of fleas, and associative learning by them-affect patterns of flea distribution between juvenile and adult rodents. The former increases whereas the latter reduces flea densities on juvenile rodents. The ability of fleas to learn to choose adult but not juvenile hosts may be due to: (a) a stronger stimulus from adults, (b) a higher profitability of adults in terms of predictability and abundance, or (c) the evolutionary importance of recognizing adult but not juvenile hosts as representatives of the species.

Descriptions of flea larvae (Siphonaptera: Hystrichopsyllidae, Ctenophthalmidae, Leptopsyllidae) of the specific parasites of the mountain beaver (Rodentia: Aplodontidae) in North America

AbstractThe larvae of the four species of primary flea parasites of the mountain beaver,Aplodontia rufa(Rafinesque), are described and illustrated for the first time, and a key to their identification is provided. The larva ofHystrichopsylla schefferiChapin is very large, with a total body length of more than 10 mm in the late third instar. Its mandible, with a series of marginal teeth along a scoop-shaped tip, is characteristic of members of the formerly recognized subgenusHystroceras. The larvae ofParatyphloceras oregonensisEwing andTrichopsylloides oregonensisEwing are very similar to one another, but the former is much larger, with a total body length of about 8 mm in the late third instar, compared with 5 mm for the latter. These two species can also be separated in all instars on the basis of the setation on the abdominal segments. The larva ofDolichopsyllus stylosus(Baker) is extraordinary. The mandible bears two enormous, tusklike setae on a swollen base, the hypopharynx is a spiny, trilobed structure without setae, and there are five processes on the labial palps instead of the four typical in other species.

Temporal dynamics of a T-cell mediated immune response in desert rodents

Immunocompetence, the general capacity of an individual host to mount an immune response against pathogens, is commonly assessed by the response to a challenge of the immune system by injection of phytohaemagglutinin (PHA). The response to PHA is commonly considered a reliable estimate of the T-cell mediated immune response. We investigated the temporal pattern of the PHA response in 10 rodent species from the Negev desert, Israel. We hypothesized that the temporal dynamics of the PHA response would differ among species with different natural patterns of flea parasitism. We injected PHA subcutaneously in the footpad of each rodent and measured its PHA response 6, 24 and 48 h after injection. Rodent species showed two types of PHA response. One type was rapid and characteristic of rodents that had either species-poor flea assemblages, or that are rarely attacked by fleas. This response peaked approximately 6 h after PHA injection. The second type of response was delayed and was typical of rodents that have either species-rich flea assemblages or high abundance and prevalence of fleas or both. Their response to PHA peaked 24 h after injection. Furthermore, rodents that responded promptly had a lower maximum response than rodents with a delayed response. Our results suggest the occurrence of a trade-off between intensity and latency of the PHA response and, therefore, the necessity to account for the relationship between maximum PHA response and time after injection when making interspecific comparisons of immunocompetence.

Immunocompetence and flea parasitism of a desert rodent

Summary Immunocompetence is the general capacity of an organism to mount an immune response against pathogens and parasites. We studied the relationship between the immunocompetence of a rodent host, Meriones crassus (Sundevall's Jird) and parasitism by the flea Xenopsylla ramesis. We hypothesized that flea parasitism affects physiological and immunological variables of the host, and that the host's level of immunocompetence affects fitness components in the flea parasite. We wanted to find out (a) the effect of flea parasitism on the haematocrit (Hct), leucocyte concentration (LC) and response to phytohaemagglutinin (PHA) of the host; (b) if and how the level of immunocompetence of the host is related to the fitness of fleas exploiting it; and (c) the relationship between the immunological and behavioural defences of the host. We measured Hct and LC and response to PHA before and after 16 days of flea infestation in Sundevall's Jird and compared these variables between jirds subjected to flea parasitism and non‐parasitized (control) animals. We evaluated egg production and hatching success in fleas exploiting hosts with different levels of immunocompetence. The effect of flea parasitism on Hct and LC of rodents was manifested by an increase in among‐host variation in the temporal changes of these variables. Response to PHA injection was significantly lower in parasitized than in control animals. Flea egg production and hatching success were not related to either LC, prior to experimental treatments, or to the PHA response of rodents. However, both of these flea fitness traits were negatively correlated with changes in LC between the 1st and the 16th days of infestation. At the end of the experiment, blood consumption of fleas was measured in jirds of both treatment groups. Fleas consumed significantly more blood when they fed on previously parasitized than on non‐parasitized animals. Among fleas that fed on previously parasitized animals, blood consumption was positively correlated with the initial LC of the hosts, and negatively correlated with differences in LC between the 1st and the 16th days of flea infestation. We found no correlation between blood consumption in fleas that fed on control animals and either immunological variable of the hosts. No trade‐off was found between behavioural and immune defences of the rodent hosts.

Age, intensity of infestation by flea parasites and body mass loss in a rodent host

Parasitism by the flea Synosternus cleopatrae does not affect the body mass of its principal rodent host, Gerbillus andersoni under natural infestation levels. We hypothesized that the lack of negative effects of flea parasitism on rodent body mass could be related either to the low level of natural infestation or to the differential susceptibility of rodent age cohorts to flea parasitism. We tested these hypotheses by measuring body mass change under flea parasitism in (a) adult rodents infested with fleas above the natural infestation level (the first hypothesis) and (b) juvenile rodents infested with fleas at natural infestation levels (the second hypothesis). Adult individuals parasitized by a number of fleas higher than in nature lost body mass at higher rates than non-parasitized control individuals. Parasitism significantly affected daily body mass change of juvenile gerbils. Juvenile rodents parasitized by fleas at the natural level of infestation lost body mass faster and gained body mass slower than control animals. We suggest that some regulating mechanisms may limit natural flea densities at a point at which the negative effect on hosts is below the accuracy of our measurements. However, natural flea densities are sufficiently high to harm the more susceptible, juvenile cohort.

AGE-DEPENDENT FLEA (SIPHONAPTERA) PARASITISM IN RODENTS: A HOST'S LIFE HISTORY MATTERS

We studied age-dependent patterns of flea infestation in 7 species of rodents from Slovakia (Apodemus agrarius, A. flavicollis, A. sylvaticus, A. uralensis, Clethrionomys glareolus, Microtus arvalis, and M. subterraneus). We estimated the age of the host from its body mass and expected the host age-dependent pattern of flea abundance, the level of aggregation, and prevalence to be in agreement with theoretical predictions. We expected that the mean abundance and the level of aggregation of fleas would be lowest in hosts of smallest and largest size classes and highest in hosts of medium size classes, whereas pattern of variation of prevalence with host age would be either convex or asymptotic. In general, mean abundance and species richness of fleas increased with an increase in host age, although the pressure of flea parasitism in terms of number of fleas per unit host body surface decreased with host age. We found 2 clear patterns of the change in flea aggregation and prevalence with host age. The first pattern demonstrated a peak of flea aggregation and a trough of flea prevalence in animals of middle age classes (Apodemus species and C. glareolus). The second pattern was an increase of both flea aggregation and flea prevalence with host age (both Microtus species). Consequently, we did not find unequivocal evidence for the main role of either parasite-induced host mortality or acquired resistance in host age-dependent pattern of flea parasitism. Our results suggest that this pattern can be generated by various processes and is strongly affected by natural history parameters of a host species such as dispersal pattern, spatial distribution, and structure of shelters.

Abundance and distribution of fleas on desert rodents: linking Taylor's power law to ecological specialization and epidemiology

We investigated variation in the abundance-prevalence relationships of fleas among 17 different flea-host associations as well as among different species of hosts and fleas in the Negev desert. We explored variation in the value of exponent of Taylor's power relationship with changes in flea community size and flea specialization (host specificity and seasonal pattern of activity). We tested if a simple epidemiological model can reproduce the pattern of the abundance-prevalence relationship. We confirmed aggregated distribution of fleas within a population of host species as well as across a whole host community and the existence of a positive relationship between local flea abundance and their prevalence. Prevalence, mean abundance and variance of abundance were significantly higher in host specific than host opportunistic fleas. When ecological specialization was considered, based on a seasonal pattern of activity, these parameters were higher in year-round-active than seasonal fleas. The degree of flea specialization and flea community richness affected the pattern of the relationship between mean abundance and its variance. Power law slopes decreased with increasing richness of flea community. A simple epidemiological model based on mean flea abundance and degree of aggregation, corrected for host sample size, can predict the observed pattern of prevalence. In some cases, observed flea prevalence was higher than that predicted from the epidemiological model. The discrepancy of the observed prevalence from that predicted by the model can be explained by either a relatively low negative effect of flea parasitism on a host (at least, in terms of pathology) or strong resistance of a host to flea parasitism or both.

Age-biased parasitism and density-dependent distribution of fleas (Siphonaptera) on a desert rodent

Parasites often confront conflicting demands when evaluating and distributing themselves among host individuals, in order to attain maximum reproductive success. We tested two alternative hypotheses about host preference by fleas in relation to the age of their rodent host. The first hypothesis suggests that fleas select adult over juvenile rodents because the latter represent a better nutritional resource (the "well-fed host" hypothesis), whereas the second hypothesis suggests that fleas prefer the weaker and less resistant juveniles because they are easier to colonise and exploit ("poorly fed host" hypothesis). We sampled fleas (Synosternus cleopatrae) on the gerbil (Gerbillus andersoni) in 23 different plots in the Negev desert and found an unequal distribution of fleas between adult and juvenile hosts. Furthermore, flea distribution changed as a function of flea density-from juvenile-biased flea parasitism (the "poorly fed host" hypothesis) at low densities to adult-biased flea parasitism (the "well-fed host" hypothesis) at high densities. Other factors that influenced flea preference were soil temperature and the presence of ticks. These results suggest that host selection is not an explicit alternative choice between adults and juveniles ("well-fed host" versus "poorly fed host" hypotheses), but rather a continuum where the distribution between adults and juveniles depends on host, parasite, and environmentally related factors.

Fleas (Siphonaptera) of the Allegheny Woodrat (Neotoma magister) in West Virginia with Comments on Host Specificity

Previous research has indicated fewer host-specific ectoparasites on woodrats of the eastern United States as compared to western woodrat species. The Allegheny woodrat (Neotoma magister) is a species of conservation concern that is associated with rocky habitats in the Appalachian and Interior Highland regions in the eastern United States. We examined Allegheny woodrat flea parasites in the core of the distribution to further elucidate patterns of ectoparasite host specificity in woodrats of the eastern United States. Of 346 fleas collected from 62 Allegheny woodrats, all but 1 were identified as Orchopeas pennsylvanicus. The single exception was a male Epitedia cavernicola, which represents only the second collection of this species from West Virginia. Unlike the eastern woodrat (Neotoma floridana), which hosts a variety of generalist flea parasites, Allegheny woodrats in our study were host to only 2 flea species, both of which are host specific to woodrats. We suggest that flea host specificity may be related to the specific habitat requirements of this species.

Immunocompetence of nestling great tits in relation to rearing environment and parentage

Theoretical models of host–parasite coevolution assume a partially genetic basis to the variability in susceptibility to parasites among hosts, for instance as a result of genetic variation in immune function. However, few empirical data exist for free–living vertebrate hosts to support this presumption. In a cross–fostering experiment with nestling great tits, by comparing nestlings of the same origin we investigated (i) the variance in host resistance against an ectoparasite due to a common genetic origin, (ii) the effect of ectoparasite infestation on cell–mediated immunity and (iii) the variance in cell–mediated immunity due to a common genetic origin. Ectoparasitic hen fleas can impair the growth of nestling great tits and nestling growth was therefore taken as a measure of host susceptibility. A common origin did not account for a significant part of the variation in host susceptibility to fleas. There was no significant overall effect of fleas on nestling growth or cell–mediated immunity, as assessed by a cutaneous hypersensitivity response. A common rearing environment explained a significant part of the variation in cell–mediated immunity among nestlings, mainly through its effect on nestling body mass. The variation in cell–mediated immunity was also related to a common origin. However, the origin–related variation in body mass did not account for the origin–related differences in cell–mediated immunity. The results of the present study thus suggest heritable variation in cell–mediated immunity among nestling great tits.

Host–habitat relations as an important determinant of spatial distribution of flea assemblages (Siphonaptera) on rodents in the Negev Desert

We studied flea assemblages on rodents in different habitats of the Ramon erosion cirque in the Negev Desert to examine whether host-habitat relations influence flea spatial distribution. Eleven flea species parasitizing 12 rodent species were recorded. There was significant positive relationship between flea species richness and body mass of the host species; no relationships were found between relative richness of flea assemblage and either the number of habitats occupied by the host species or the size of host geographical range. The differences in pattern of flea parasitism among habitat types within host species were determined by both environmental features of a habitat and the specific pattern of habitat use by rodents. There was replacement of Xenopsylla conformis by Xenopsylla ramesis on Meriones crassus and Gerbillus dasyurus among different habitats. The results of ordination of the flea collections from each individual host demonstrated that the flea assemblages were segregated mainly along 4 axes, which explained 86% of total variance. Each of the ordination axes corresponded with a change in flea species composition. The directions of these changes were (1) among-hosts within a habitat and (2) among-habitats within a host.