Fleas from bird nests in southwestern Tuva

14 species of fleas were recorded from 173 nests of 47 species of birds. Most abundant of them are Ceratophyllus vagabundus, C. gallinae, C. borealis. The abundance of fleas was found to depend on season and hosts' habitat. The above species were most frequently encountered in nests in May. The high abundance index of fleas was registered in birds nesting in hollows, burrows of small mammals and in clefts of rocks.     

Deconstructing spatial patterns in species composition of ectoparasite communities: the relative contribution of host composition,environmental variables and geography

Aim We determined whether dissimilarity in species composition between parasite communities depends on geographic distance, environmental dissimilarity or host faunal dissimilarity, for different subsets of parasite species with different levels of host specificity. Location Communities of fleas parasitic on small mammals from 28 different regions of the Palaearctic. Method Dissimilarities in both parasite and host species composition were computed between each pair of regions using the Bray–Curtis index. Geographic distances between regions were also calculated, as were measures of environmental dissimilarity consisting of the pairwise Euclidean distances between regions derived from elevation, vegetation and climatic variables. The 136 flea species included in the dataset were divided into highly host‐specific species (using 1–2 host species per region, on average), moderately host‐specific species (2.2–4 hosts per region) and generalist species (>4 hosts per region). The relative influence of geographic distance, host faunal dissimilarity and environmental dissimilarity on dissimilarity of flea species composition among all regions was analysed for the entire set of flea species as well as for the three above subsets using multiple regressions on distance matrices. Results When including all flea species, dissimilarity in flea species composition was affected by all three independent variables, although the pure effect of dissimilarity in host species composition was the strongest. Results were different when the subsets of fleas differing in host specificity were treated separately. In particular, dissimilarity in species composition of highly host‐specific fleas increased solely with environmental dissimilarity, whereas dissimilarity for both moderately specific and non‐specific fleas increased with both geographic distance and dissimilarity in host species composition. Main conclusions Host specificity seems to dictate which of the three factors considered is most likely to affect the dissimilarity between flea communities. Counter‐intuitively, environmental dissimilarity played a key role in determining dissimilarity in species composition of highly host‐specific fleas, possibly because, although their presence in a region relies on the occurrence of particular host species, their abundance is itself mostly determined by climatic conditions. Our results show that deconstructing communities into subsets of species with different traits can make it easier to uncover the mechanisms shaping geographic patterns of diversity.     

Species composition, host association and niche differentiation in fleas of small mammals in the Ilmen-Volkhov lowland

Species composition, abundance, annual cycles, and host association of fleas parasitizing small mammals were investigated. The problem of niche differentiation in these insects is considered on the base of the comparative analysis of their annual cycles. The annual cycles of the fleas are revealed to be similar in the case of few number of flea species in parasite community. Thus, two species parasitizing Sorex araneus (Doratopsylla dasycnema and Palaeopsylla soricis), as well as three species associated with Apodemus uralensis (Megabothris turbidus, Ctenophthalmus agyrtes, and Ct. uncinatus) have equal phenology of parasitizing. The fleas community of Clethrionomys glareolus is characterized by a large species number and high diversity of the annual cycles. The differentiation by the seasons of parasitizing is observed most clearly in the dominant flea species, namely Amalaraeus penicilliger, Ct. uncinatus, and Peromyscopsylla bidentata. The periods of imaginal life are overlapped significanly in these species, but they are differed by the season of dominance. Ct. uncinatus predominates in spring and summer, while P. bidentata predominates in autumn, and A. penicilliger predominates in winter and early spring. It may be noted also, that niche partitioning was not observed in the fleas having wide range of hosts. The imaginal life of such fleas usually does not go beyond the warm season.     

Local factors associated with on‐host flea distributions on prairie dog colonies

Outbreaks of plague, a flea‐vectored bacterial disease, occur periodically in prairie dog populations in the western United States. In order to understand the conditions that are conducive to plague outbreaks and potentially predict spatial and temporal variations in risk, it is important to understand the factors associated with flea abundance and distribution that may lead to plague outbreaks. We collected and identified 20,041 fleas from 6,542 individual prairie dogs of four different species over a 4‐year period along a latitudinal gradient from Texas to Montana. We assessed local climate and other factors associated with flea prevalence and abundance, as well as the incidence of plague outbreaks. Oropsylla hirsuta, a prairie dog specialist flea, and Pulex simulans, a generalist flea species, were the most common fleas found on our pairs. High elevation pairs in Wyoming and Utah had distinct flea communities compared with the rest of the study pairs. The incidence of prairie dogs with Yersinia pestis detections in fleas was low (n = 64 prairie dogs with positive fleas out of 5,024 samples from 4,218 individual prairie dogs). The results of our regression models indicate that many factors are associated with the presence of fleas. In general, flea abundance (number of fleas on hosts) is higher during plague outbreaks, lower when prairie dogs are more abundant, and reaches peak levels when climate and weather variables are at intermediate levels. Changing climate conditions will likely affect aspects of both flea and host communities, including population densities and species composition, which may lead to changes in plague dynamics. Our results support the hypothesis that local conditions, including host, vector, and environmental factors, influence the likelihood of plague outbreaks, and that predicting changes to plague dynamics under climate change scenarios will have to consider both host and vector responses to local factors.     

Distribution of fleas (Siphonaptera) among small mammals: mean abundance predicts prevalence via simple epidemiological model

We used data on the abundance and distribution of fleas parasitic on small mammals in Slovakia and aimed: (i) to confirm a positive relationship between abundance and distribution fleas within and across host species; and (ii) to test if prevalence of fleas can be reliably predicted from a simple epidemiological model that takes into account flea mean abundance and its variance. Prevalence of a flea species increased with an increase in its mean abundance both within and across host species. We calculated prevalences both for each flea-host association and for each flea species across all hosts. Observed prevalences did not differ significantly from those predicted by the epidemiological model using parameters of Taylor's power relationship between mean abundance of fleas and its variance. Regressions of predicted prevalences against observed prevalences produced slope values that did not differ significantly from unity and were independent of scale (within or across host species). Our results demonstrated that up to 96% of variance in flea prevalence can be explained solely by their mean abundance. We concluded that, in general, there is no need to invoke other, more complex factors for the explanation of the variation in flea prevalence.     

Characteristics of distribution of fleas from small mammals and birds in the southern taiga of Priirtysh'ie]

The analysis of the landscape distribution of fleas from small mammals and birds in the southern taiga of Priirtishje is given. According to their abundance and faunistic composition the population of fleas from small mammals can be arranged into four groups: fleas of forest floodland landscape, those of forest-meadow floodland landscape, fleas of settlements and bogs.     

Ectoparasitic "jacks-of-all-trades": relationship between abundance and host specificity in fleas (Siphonaptera) parasitic on small mammals

Animal species with larger local populations tend to be widespread across many localities, whereas species with smaller local populations occur in fewer localities. This pattern is well documented for free-living species and can be explained by the resource breadth hypothesis: the attributes that enable a species to exploit a diversity of resources allow it to attain a broad distribution and high local density. In contrast, for parasitic organisms, the trade-off hypothesis predicts that parasites exploiting many host species will achieve lower mean abundance on those hosts than more host-specific parasites because of the costs of adaptations against multiple defense systems. We test these alternative hypotheses with data on host specificity and abundance of fleas parasitic on small mammals from 20 different regions. Our analyses controlled for phylogenetic influences, differences in host body surface area, and sampling effort. In most regions, we found significant positive relationships between flea abundance and either the number of host species they exploited or the average taxonomic distance among those host species. This was true whether we used mean flea abundance or the maximum abundance they achieved on their optimal host. Although fleas tended to exploit more host species in regions with either larger number of available hosts or more taxonomically diverse host faunas, differences in host faunas between regions had no clear effect on the abundance-host specificity relationship. Overall, the results support the resource breadth hypothesis: fleas exploiting many host species or taxonomically unrelated hosts achieve higher abundance than specialist fleas. We conclude that generalist parasites achieve higher abundance because of a combination of resource availability and stability.     

云南省玉龙鼠疫疫源地野外鼠形动物寄生蚤丰盛度影响因素分析

【目的】分析云南省玉龙鼠疫疫源地野外鼠形动物寄生蚤丰盛度的影响因素。【方法】选取云南省玉龙鼠疫疫源地3个海拔区域,按4个季节进行野外捕鼠,捕获的鼠形动物用梳检法收集体表寄生蚤并在显微镜下分类鉴定。通过实际测量和实地观察相结合的方式收集潜在影响鼠形动物寄生蚤丰盛度的因素包括鼠形动物特征变量指标(如种类、年龄、性别、体长、体重)、环境和气象因子(如海拔、季节)等数据。采用EpiData 3.02软件建立数据库,在R软件下使用跨栏负二项分布回归分析鼠形动物寄生蚤丰盛度的影响因素。【结果】从捕获的884只鼠形动物中检获寄生蚤9种484头,以特新蚤指名亚种、方叶栉眼蚤、无值大锥蚤、云南栉眼蚤为主(86.16%)。回归分析显示： 2 700-3 000 m和3 000 m以上海拔鼠形动物染蚤概率较2 400-2 700 m分别增加1.27和3.72倍;湿度高于70%时,鼠形动物染蚤概率较湿度≤70%时减少41%;与齐氏姬鼠的染蚤概率相比,中华姬鼠的染蚤概率降低50%,大绒鼠的染蚤概率增加79%;体长超过104 mm的鼠形动物染蚤概率较体长≤104 mm的鼠形动物染蚤概率增加76%;气温高于15℃时,鼠形动物染蚤数量较温度≤15℃时降低67%;成年鼠形动物的染蚤数量较未成年鼠形动物的染蚤数量增加2.25倍;与春季相比,夏季的染蚤数量增加2.00倍,秋季的染蚤概率减少48%,冬季的染蚤概率和染蚤数量分别增加1.44和1.06倍。【结论】玉龙鼠疫疫源地野外鼠形动物寄生蚤以特新蚤指名亚种、方叶栉眼蚤、无值大锥蚤、云南栉眼蚤为优势蚤种。鼠形动物寄生蚤丰盛度与海拔、季节、气温、湿度等环境气象因子及鼠形动物种类、体长、年龄等鼠形动物特征变量密切相关。     

Abundance patterns and coexistence processes in communities of fleas parasitic on small mammals

The abundance of a given species in a community is likely to depend on both the total abundance and diversity of other species making up that community. A large number of co-occurring individuals or co-occurring species may decrease the abundance of any given species via diffuse competition; however, indirect interactions among many co-occurring species can have positive effects on a focal species. The existence of diffuse competition and facilitation remain difficult to demonstrate in natural communities. Here, we use data on communities of fleas ectoparasitic on small mammals from 27 distinct geographical regions to test whether the abundance of any given flea species in a community is affected by either the total abundance of all other co-occurring flea species, or the species richness and/or taxonomic diversity of the flea community. At all scales of analysis, i.e. whether we compared the same flea species on different host species, or different flea species, two consistent results emerged. First, the abundance of a given flea species correlates positively with the total abundance of all other co-occurring flea species in the community. Second, the abundance of any given flea species correlates negatively with either the species richness or taxonomic diversity of the flea community. The results do not support the existence of diffuse competition in these assemblages, because the more individuals of other flea species are present on a host population, the more individuals of the focal species are there as well. Instead, we propose explanations involving either apparent facilitation among flea species via suppression of host immune defenses, or niche filtering processes acting to restrict the taxonomic composition and abundance of flea assemblages.     

Parasite fauna of the water vole (Arvicola terrestris) and its nests in the south of Western Siberia

Fauna of parasitic and free-living arthropods associated the water vole Arvicola terestris and its nests in various landscape zones and subzones of the south of Western Siberia has been studied. Total abundance of gamasid mites and ticks (Gamasoidea, Ixodidae), fleas and nidicolous arthropods in nests is high, and the set of nidicolous and parasite species is quite diverse, but everywhere the parasite fauna is characterized by a small amount of species reaching a high abundance: Laelaps muris on the voles, Haemogamasus ambulans in nests, Ixodes apronophorus and Megpbotris walkeri both on the voles and nests. Parasitic arthropods living on the voles or in their nests are characterized by higher and stables indices of infection, while these parameters for free-living arthropods were variable. The list of mesostigmatic mites parasitizing the water vole and its nests in the south of Western Siberia (Adamovich, Krylov, 2001) has been considerably supplemented. In total, the fauna of parsitiform mites (Acari: Mesostigmata and Ixodiddes) and fleas (Siphonaptera) associated with the water vole in the south of Western Siberia is represented by 97 arthropod species of 19 families, including 74 species of mesostigmatic mites (Gamasoidea), 6 species of ticks (Ixodidae) and 17 species of fleas.     

Interaction frequency across the geographical range as a determinant of host specialisation in generalist fleas

The strength of interspecific interactions varies over geographical scales, and can influence patterns of resource specialisation. Even with gene flow preventing local adaptation of a consumer to particular resources, we might expect that across its entire range, the consumer would show some specialisation for the resource types most likely to be encountered across the localities where it occurs. We tested the hypothesis that generalist fleas are more successful at exploiting small mammalian host species with which they co-occur frequently across their geographical range than host species that, though suitable, are encountered less frequently. This hypothesis was tested with data on 121 flea species compiled from field surveys across 35 regions of the Palaearctic. Using abundance (mean number of individual fleas per individual host) as a measure of flea success on a particular host species, positive correlations between flea abundance and the frequency of co-occurrence of a flea with each of its hosts amongst all regions surveyed were found in all but two of the flea species investigated, with one-fifth of these being significant. If overlap in geographical range between flea and host is used as a measure of frequency of encounters instead of the actual proportion of regions where they both occur, similar patterns are observed, though they are much weaker. In a comparative analysis across all flea species, there were significant relationships between the average abundance of fleas and average values of both measures of frequency of encounters (proportion of sites where they co-occur and range overlap), even when correcting for potential phylogenetic influences. The results suggest that for any given flea species, host species more commonly encountered throughout the spatial range of the flea are generally those on which the flea does best. Interaction frequency may be a key determinant of specialisation and abundance in host-parasite systems.     

Trait‐based and phylogenetic associations between parasites and their hosts: a case study with small mammals and fleas in the Palearctic

We investigated the associations between ecological (density, shelter structure), morphological (body mass, hair morphology) and physiological traits (basal metabolic rate) of small mammals and ecological (seasonality of reproduction, microhabitat preferences, abundance, host specificity) and morphological (presence and number of combs) traits of their flea parasites that shape host selection processes by fleas. We adapted the extended version of the three‐table ordination and linked species composition of flea assemblages of host species with traits and phylogenies of both hosts and fleas. Fleas with similar trait values, independent of phylogenetic affinities, were clustered on the same host species. Fleas possessing certain traits selected hosts possessing certain traits. Fleas belonging to the same phylogenetic lineage were found on the same host more often than expected by chance. Certain phylogenetic lineages of hosts harbored certain phylogenetic lineages of fleas. The process of host selection by fleas appeared to be determined by reciprocal relationships between host and flea traits, as well as between host and flea phylogenies. We concluded that the connection between host and flea phylogenies, coupled with the connection between host and flea traits, suggests that the species compositions of the host spectra of fleas were driven by the interaction between historical processes and traits.     

The longevity of Leptopsylla segnis fleas (Siphonaptera: Leptopsyllidae)

In experiments, the mean life duration of fleas Leptopsylla segnis on white mice (abundance of fleas within natural limits, up to 10 fleas per mouse) was 22.7 days in females and 18.8 day in males. Maximum life duration was 51 and 37 days respectively. In cases, when the initial numbers of fleas were 20 and 28-34 fleas, the duration of life was decreased. The maximum limit decreased greater than the mean duration of life. A survival dynamics of fleas depended upon the flea number. It was found out, that in cases of high abundance of fleas in the beginning of experiments, the mortality rate of males was lower than in females. During the stay on a host the fleas lost gradually an ability to endure a starvation. Possible mechanisms of the regulation of flea abundance are discussed.     

Effects of fleas on nest success of Arctic barnacle geese: experimentally testing the mechanism

Parasites have detrimental effects on their hosts’ fitness. Therefore, behavioural adaptations have evolved to avoid parasites or, when an individual is already in contact with a parasite, prevent or minimize infections. Such anti‐parasite behaviours can be very effective, but can also be costly for the host. Specifically, ectoparasites can elicit strong host anti‐parasite behaviours and interactions between fleas (Siphonaptera) and their hosts are one of the best studied. In altricial bird species, nest fleas can negatively affect both parent and offspring fitness components. However, knowledge on the effects of fleas on precocial bird species is scarce. Research on geese in the Canadian Arctic indicated that fleas have a negative impact on reproductive success. One possible hypothesis is that fleas may affect female incubation behaviour. Breeding females with many fleas in their nest may increase the frequency and/or duration of incubation breaks and could even totally desert their nest. The aim of our study was to 1) determine if a similar negative relationship existed between flea abundance and reproductive success in our study colony of Arctic breeding barnacle geese Branta leucopsis and 2) experimentally quantify if such effects could be explained by a negative effect of nest fleas on female behaviour. We compared host anti‐parasite and incubation behaviour between experimentally flea‐reduced and control nests using wildlife cameras and temperature loggers. We found that flea abundance was negatively associated with hatching success. We found little experimental support, however, for changes in behaviour of the breeding female as a possible mechanism to explain this effect.     

The seasonal dynamics of fleas (Siphonaptera) on bank voles (Clethrionomys glareolus) in the north part of Novgorod region

The twelve flea species were revealed on bank voles. Only four of them (Amalaraeus penicillige, Ctenophthalmus uncinatus, Megabothris turbidus, Peromescopsylla bidentata) were abundant in some seasons of the year. Four other species (Ct. agyrtes, Hystrichopsylla talpae, P. silvatica, Rhadinopsylla integella) are the parasites of bank vole too but their numbers were always low in the study area. The four last species (Amphypsylla rossica, M. walkeri, Doratopsylla dasycnema, Palaeopsylla soricis) are not peculiar to bank vole. They occurs on it occasionally from other animals--the voules of Mucrotus and shrews. The most species diversity of fleas on bank vole was observed at the period from August to October, the least one--in late winter, spring and early summer. The total abundance indices of fleas on the voles (mean number of the insects per host) ranged in different months from 0.17 to 5.65. The time of minimum flea numbers was August-September. The peak abundance was reached in springtime (March-April).     

Faunistic analysis of the fleas on small mammals in the trans-Aral Sea area

Materials on occurrence and abundance of 36 species of fleas on 17 species of small mammals are systematized. A great similarity between the faunas of ectoparasites of rodents and predators has been shown by means of special indices. The conception of parasitic field is formulated which implies the phenomenon of community of the fauna of plague vectors parasitic on its potential carriers. Some aspects of the formation of parasitic field and its possible effect the epizootic process are considered. It is established that the similarity between the faunas of fleas from different animals is ensured in this region first of all by a wide distribution of specific parasites of gerbils.     

Ecology of Lepidoptera associated with bird nests in mid‐Wales,UK

1. Bird nests are ubiquitous but patchy resources in many terrestrial habitats. Nests can support diverse communities of commensal invertebrates, especially moths (Lepidoptera). However, there is a shortage of information on the moths associated with bird nests, and the factors influencing their abundance, diversity and composition. 2. Two hundred and twenty‐four nests, from 16 bird species, were sampled from sites in mid‐Wales (UK) and the moths that emerged from them were recorded. 3. Seventy eight percent of nests produced moths, with 4657 individuals of ten species recorded. Moth communities were dominated by generalist species rather than bird nest specialists. 4. Open nests built in undergrowth supported significantly fewer moths than nests in enclosed spaces (for example, nesting boxes). The occurrence of fleas was positively associated with the incidence and abundance of moths. There was no evidence that different nest types supported different moth communities.     

Ecological characteristics of flea species relate to their suitability as plague vectors

The ability of vector-borne diseases to persist and spread is closely linked to the ecological characteristics of the vector species they use. Yet there have been no investigations of how species used as vectors by pathogens such as the plague bacterium differ from closely related species that are not used as vectors. The plague bacterium uses mammals as reservoir hosts and fleas as vectors. The ability of different fleas to serve as vectors is assumed to depend on how likely they are to experience gut blockage following bacterial multiplication; the blockage causes fleas to regurgitate blood into a wound and thus inject bacteria into new hosts. Beyond these physiological differences, it is unclear whether there exist fundamental ecological differences between fleas that are effective vectors and those that are not. Here, using a comparative analysis, we identify clear associations between the ability of flea species to transmit plague and their ecological characteristics. First, there is a positive relationship between the abundance of flea species on their hosts and their potential as vectors. Second, although the number of host species exploited by a flea is not associated with its potential as a vector, there is a negative relationship between the ability of fleas to transmit plague and the taxonomic diversity of their host spectrum. This suggests a correlation between some ecological characteristics of fleas and their ability to develop the plague blockage. The plague pathogen thus uses mainly abundant fleas specialized on a narrow taxonomic range of mammals, features that should maximize the persistence of the disease in the face of high flea mortality, and its transmission to suitable hosts only. This previously unrecognized pattern of vector use is of importance for the persistence and transmission of the disease.Electronic Supplementary Material Supplementary material is available to authorised users in the online version of this article at .     

Detection of Rickettsia spp. and host and habitat associations of fleas (Siphonaptera) in eastern Taiwan

Rickettsia typhi and Rickettsia felis (Rickettsiales: Rickettsiaceae) are two rickettsiae principally transmitted by fleas, but the detection of either pathogen has rarely been attempted in Taiwan. Of 2048 small mammals trapped in eastern Taiwan, Apodemus agrarius Pallas (24.5%) and Mus caroli Bonhote (24.4%) (both: Rodentia: Muridae) were the most abundant, and M. caroli hosted the highest proportion of fleas (63.9% of 330 fleas). Two flea species were identified: Stivalius aporus Jordan and Rothschild (Siphonaptera: Stivaliidae), and Acropsylla episema Rothschild (Siphonaptera: Leptopsyllidae). Nested polymerase chain reaction targeting parts of the ompB and gltA genes showed six fleas to be positive for Rickettsia spp. (3.8% of 160 samples), which showed the greatest similarity to R. felis, Rickettsia japonica, Rickettsia conorii or Rickettsia sp. TwKM01. Rickettsia typhi was not detected in the fleas and Rickettsia co-infection did not occur. Both flea species were more abundant during months with lower temperatures and less rainfall, and flea abundance on M. caroli was not related to soil hardness, vegetative height, ground cover by litter or by understory layer, or the abundance of M. caroli. Our study reveals the potential circulation of R. felis and other rickettsiae in eastern Taiwan, necessitating further surveillance of rickettsial diseases in this region. This is especially important because many novel rickettsioses are emerging worldwide.     

Geographical patterns of abundance: testing expectations of the ‘abundance optimum’ model in two taxa of ectoparasitic arthropods

Aim The ‘abundance optimum’ hypothesis predicts that species abundance peaks in the locality with the most favourable conditions and decreases with an increase of distance from that locality. We tested this prediction for 9 fleas and 13 gamasid mite species. Location We used published data on fleas and gamasid mites that are parasitic on small mammals throughout the Palaearctic. Methods For each ectoparasite, we computed the correlation between the relative abundance on its principal host species in a region and the distance from that region to the region of maximum abundance. Then, the correlation coefficients were used in a meta‐analysis. We also made a cross‐species comparison between relative abundances in localities (a) closest to and (b) furthest from the locality of maximum abundance. Results Although the relationship between the relative abundance in a region and the distance from that region to the region of maximum abundance was negative in 19 out of 22 ectoparasites, it was only statistically significant in three of them. However, a meta‐analysis of coefficients of correlations across all species revealed a significant negative effect of the distance from the region of maximum abundance on relative abundance in a particular region. A cross‐species comparison between relative abundances in the localities closest to and furthest from the locality of maximum abundance demonstrated that the former were significantly higher than the latter. Main conclusions A lack of strict host specificity in the ectoparasites studied, and the absence of any strong spatial correlations among the environmental variables affecting ectoparasite reproduction and abundance, may provide an explanation for the spatial independence in abundance values of most species. However, a preference for a particular host even in host‐opportunistic parasites combined with species‐specific environmental preferences could be the reason behind the weak, but significant, negative abundance–distance relationship across species. The contradiction between results obtained when separate species were considered and when the overall pattern was analysed across species suggests that there exists a general underlying spatial pattern that can often be masked by other factors.